United States
Environmental Protection
Agency
Strategic Studies Staff
Office of Policy and
Resources Management
Washington, DC 20460
September 1983
v>EPA
Can We Delay A
Greenhouse Warming?
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COVER-APOLLO 13 VIEW OF EARTH WITH SOUTHWESTERN U.S. AND NORTHERN MEXICO VISIBLE
NASA PHOTO
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CAN WE DELAY A GREENHOUSE WARMING?
The Effectiveness and Feasibility
of Options to Slow a Build-Up
of Carbon Dioxide in the Atmosphere
STEPHEN SEIDEL
U.S. Environmental Protection Agency
and
DALE KEYES
Consultant
Strategic Studies Staff
Office of Policy Analysis
Office of Policy and Resources Management
Washington, D.C. 20460
September 1983
-------
For sale by the Superintendent of Documents, U.S. Government Printing Office
Washington, D.C. 20402
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TABLE OF CONTENTS
CHAPTER PAGE
EXECUTIVE SUMMARY i
1. C02 AND THE GREENHOUSE EFFECT: STUDY OVERVIEW 1-1
BACKGROUND TO THE GREENHOUSE EFFECT L-2
CURRENT UNDERSTANDING OF THE POTENTIAL
FOR GLOBAL WARMING 1-3
IMPLICATIONS OF THE GREENHOUSE EFFECT 1-5
POSSIBLE ADVERSE CONSEQUENCES 1-7
POSSIBLE BENEFICIAL CONSEQUENCES 1-9
NET EFFECTS AND TRANSITIONAL PROBLEMS L-9
DEFINING THE APPROPRIATE RESPONSE 1-10
EVALUATING THE PREVENTION STRATEGY 1-13
METHODOLOGICAL APPROACH 1-14
BASELINE SCENARIOS 1-15
POLICY OPTIONS 1-16
MEASURES OF EFFECTIVENESS 1-16
MEASURES OF FEASIBILITY 1-18
FINDINGS AND CONCLUSIONS 1-19
2. SCIENTIFIC BASIS FOR A GREENHOUSE WARMING 2-1
ROLE OF GREENHOUSE GASES , 2-1
COMPARISONS WITH OTHER PLANETS 2-3
EVIDENCE FROM CLIMATE MODELS 2-4
TIMING OF TEMPERATURE RISE 2-6
THE ORIGIN AND EXCHANGE OF CO2
IN THE ENVIRONMENT 2-7
THE CARBON CYCLE: PAST, PRESENT, AND FUTURE... 2-9
FRACTION OF CO2 FROM FOSSIL FUELS THAT
REMAINS AIRBORNE 2-11
INCREASES IN OTHER GREENHOUSE GASES 2-12
NITROUS OXIDE 2-12
METHANE 2-13
CHLOROFLUOROCARBONS 2-14
COMBINED TEMPERATURE EFFECTS: 1970-80 2-15
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- 2 -
CHAPTER PAGE
POSSIBLE EFFECTS OF A WARMER EARTH 2-15
RECONSTRUCTING PAST CLIMATES 2-16
MODELING FUTURE CLIMATES 2-20
DETECTING A FUTURE GREENHOUSE WARMING 2-21
SUMMARY 2-22
3. METHODOLOGY FOR PROJECTING FUTURE ENERGY
AND CO2 SCENARIOS 3-1
PROJECTING ENERGY USE AND C02 EMISSIONS 3-3
ENERGY DEMAND PARAMETERS 3-7
ENERGY SUPPLY PARAMETERS 3-11
BALANCING SUPPLY AND DEMAND 3-17
ESTIMATING CO2 EMISSIONS 3-18
PROJECTING ATMOSPHERIC CO2 LEVELS 3-19
PROJECTING ATMOSPHERIC TEMPERATURE LEVELS 3-22
4. THE EFFECTIVENESS OF ENERGY POLICIES
FOR CONTROLLING CO2 4-1
BASELINE SCENARIOS 4-2
MID-RANGE BASELINE 4-2
Energy Supply and Demand 4-2
CO2 and Atmospheric Responses 4-7
OTHER BASELINE SCENARIOS 4-14
Energy Supply and Demand ., 4-14
CO2 and Atmospheric Responses 4-23
OTHER BASELINE SENSITIVITY TESTS 4-26
POLICY OPTIONS 4-27
TAXES ON CO2 EMISSIONS 4-27
Energy Supply and Demand 4-28
CO2 and Atmospheric Responses 4-31
FUEL BANS 4-33
Energy Supply and Demand 4-33
C02 and Atmospheric Responses 4-36
SUMMARY 4_41
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CHAPTER PAGE
5. THE ECONOMIC AND POLITICAL FEASIBILITY
OF ENERGY POLICIES 5-1
EFFECTS OF POLICIES ON COAL RESOURCES 5-2
GLOBAL DISTRIBUTION OF COAL 5-2
CHANGES IN VALUE OF COAL RESERVES 5-5
CHANGES IN FUEL PRICES 5-7
CAPITAL INVESTMENTS IN COAL 5-7
EFFECTS OF BANS ON SHALE OIL AND SYNFUELS 5-14
OTHER IMPEDIMENTS TO POLICY IMPLEMENTATION 5-15
SUMMARY 5-19
6. NONENERGY OPTIONS FOR CONTROLLING CO2 EMISSIONS.... 6-1
OPTIONS FOR CONTROLLING CO2 EMISSIONS 6-1
SEQUESTERING CO2 USING TREES 6-5
LAND REQUIREMENTS 6-6
FERTILIZER REQUIREMENTS 6-7
COSTS OF SEQUESTERING 6-9
OFFSETTING THE GREENHOUSE WARMING 6-13
SUMMARY 6-14
7 . CONCLUSIONS 7-1
EFFECTIVENESS OF POLICIES AND SENSITIVITY
OF RESULTS 7-1
FEASIBILITY OF POLICY OPTIONS 7-5
MODELING ASSUMPTIONS 7-6
IMPLICATIONS OF FINDINGS 7-7
APPENDICES
A. ENERGY SUPPLY OPTIONS
B. THE IEA ENERGY AND C02 EMISSIONS MODEL
C. THE ORNL CARBON CYCLE MODEL
D. THE GISS ATMOSPHERIC TEMPERATURE MODEL
E. COUPLING THE ORNL AND GISS MODELS TO ESTIMATE
THE RETENTION RATIO
GLOSSARY OF ENERGY UNITS
REFERENCES
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LIST OF FIGURES
FIGURE PAGE
1-1 Range of Global-Scale Mean Temperature, With
and Without the Projected Greenhouse Effect 1-6
2-1 Monthly Atmospheric Carbon Dioxide Concentration
at Mauna Loa Observatory 2-8
2-2 Exchangeable Carbon Reservoirs and Fluxes. 2-10
2-3 Temperature Increases for Several Greenhouse
Gases , 2-17
2-4 Modeled Versus Observed Temperature Trends.. 2-23
3-1 Study Methodology 3-2
3-2 Geopolitical Regions in the IEA Model 3-5
3-3 Structure of the IEA Model 3-6
3-4 Final Atmospheric CO2 Retention Ratios
for Four Types of CO2 Emissions Scenarios 3-21
4-1 Mid-range Baseline Scenario: Energy Use
Characteristics 4-4
4-2 CO2 Modeling Results for the Mid-range Baseline
Scenario 4-8
4-3 Geographic Distribution of CO2 Emissions
for the Mid-range Baseline Scenario 4-10
4-4 Sensitivity of Mid-range Baseline Temperature
Estimates 4-12
4-5 High Renewable vs. Mid-range scenarios:
Fuel Use Characteristics 4-16
4-6 High Nuclear vs. Mid-range Scenarios:
Energy Use Characteristics 4-18
4-7 High Electric vs. Mid-range Scenarios:
Energy Use Characteristics 4-20
4-8 Low Demand vs. Mid-range Scenarios:
Energy Use Characteristics 4-22
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- 2 -
FIGURE PAGE
4-9 High Fossil vs. Mid-range Scenarios:
Energy Use Characteristics. . 4-24
4-10 CO2 Modeling Results for Alternative Baseline
Scenarios 4-25
4-11 CO2 Tax Policies vs. Mid-range Baseline
Scenarios: Energy Use Characteristics 4-29
4-12 CO2 Modeling Results for Tax Policy
and Mid-range Baseline Scenarios 4-32
4-13 Fuel Bans vs. Mid-range Baseline Scenarios:
Energy Use Characteristics 4-34
4-14 CO2 Modeling Results for Fuel Bans
and Mid-range Baseline Scenarios 4-37
4-15 Geographic Distribution of CC>2 Emissions
for Selected Fuel Bans and the Mid-range
Baseline Scenario 4-38
5-1 Global Coal Resources 5-4
5-2 Proved Recoverable Coal Reserves 5-4
5-3 Process Leading to Action 5-16
7-1 Changes in the Date of a Two Degree Warming 7-2
7-2 Changes in Temperature Projected for 2100 7-4
B-l Application of CC>2 Emissions Coefficients
in the IEA Model B_8
C-2 Structure of the ORNL Global Carbon Cycle Model... c-2
E-l Key Features of the ORNL-GISS Coupling
Methodology E_2
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LIST OF TABLES
TABLE PAGE
3-1 Baseline Values for Population, GNP, Technological
Change 3-8
3-2 Breakthrough Prices for Emerging Energy Sources
in the Mid-range Baseline Scenario 3-15
3-3 Breakthrough Prices for Traditional Energy
Sources in the Mid-range Baseline Scenario 3-21
3-4 Parameter Values for the GISS Model 3-26
5-1 Approximate Capital Investment for International
Coal Chain: Western U.S. to Japanese Power Plant. 5-9
5-2 Approximate Capital Investment for Domestic
Coal Chain: Western U.S. to West South Central
Power Plant 5-10
5-3 WOCOL Forecasted Net Additions of Coal-Fired
Power Plants in OECD Countries: 1977-2000 5-12
5-4 WOCOL Forecasted Cumulative Coal Chain Investments
for WOCOL Countries in OECD: 1977-2000 5-13
6-1 Costs of Generating Electricity With and Without
CO2 Control for Initial Power Plant Capacity of
200-MW(e) 6-4
6-2 Fertilizer Requirements for Growing American
Sycamore Trees, Compared With World Fertilizer
Production — July 1979-June 1980 6-8
6-3 Fertilizer Requirements for Giant Leucaena,
Compared with U.S./Canada and World Production
Fertilizer Production — July 1978-June 1979 6-11
A-l Worldwide Energy Production in 1979 A-2
A-2 Summary of Energy Supplies A-4/5
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ACKNOWLEDGEMENTS
Many individuals made valuable contributions to this study.
In particular, Dr. James Hansen and his colleagues at NASA's
Goddard Institute for Space Studies provided an atmospheric
temperature model, and Dr. William Emanuel of Oak Ridge National
Laboratories made available a carbon cycle model, both of
which we employed in the study. They also provided valuable
guidance in the application of these models. An energy and CO2
emissions model was obtained from the Institute for Energy
Analysis. Alan Truelove of Pechan and Associates, Inc. assisted
in operating and integrating the various computer programs.
We would also like to thank Ken Schweers and Mike Gibbons of
ICF Inc., who contributed background information and insights
into the economic costs of limiting fossil fuel use.
Martin Wagner, Acting Director of EPA's Energy Policy Division,
and John Hoffman, who directs EPA's research program on greenhouse
effects, provided useful comments on previous drafts. We are
also indebted to several other reviewers: Dr. Martin Miller
and Dr. David Rose, both of the Massachusetts Institute of
Technology; Dr. Henry Lee, the Director of Harvard's Energy
and Environmental Policy Center; and Jesse Ausebel of the
National Academy of Sciences. However, the contents and conclusions
of the study remain the responsibility of the authors.
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EXECUTIVE SUMMARY
Evidence continues to accumulate that increases in atmos-
pheric carbon dioxide (CC>2) and other "greenhouse" gases will
substantially raise global temperature. While considerable
uncertainty exists concerning the rate and ultimate magnitude
of such a temperature rise, current estimates suggest that a 2°C
(3.6°F) increase could occur by the middle of the next century,
and a 5°C (9°F) increase by 2100. Such increases in the span of
only a few decades represent an unprecedented rate of atmospheric
warming.
Temperature increases are likely to be accompanied by dramatic
changes in precipitation and storm patterns and a rise in global
average sea level. As a result, agricultural conditions will be
significantly altered, environmental and economic systems poten-
tially disrupted, and political institutions stressed.
Responses to the threat of a greenhouse warming are polarized.
Many have dismissed it as too speculative or too distant to be of
concern. Some assume that technological options will emerge to
prevent a warming or, at worst, to ameliorate harmful consequences.
Others argue that only an immediate and radical change in the rate
of CC>2 emissions can avert worldwide catastrophy. The risks are
high in pursuing a "wait and see" attitude on one hand, or in
acting impulsively on the other.
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- 11 -
This study aims to shed light on the debate by evaluating
the usefulness of various strategies for slowing or limiting a
global warming. Better information is essential if scientific
researchers, policymakers, and private sector decisionmakers
are to work together effectively in addressing the threat of
climate change.
FOCUS OF STUDY
Because increases in atmospheric CC>2 primarily result from
the use of fossil fuels, one logical response to the threat of
climate change is to reduce global dependence on these energy
sources. This study takes a first look at whether specific
policies aimed at limiting the use of fossil fuels would prove
effective in delaying temperature increases over the next 120
years. Specifically, it examines whether a tax on the use of
fossil fuels or a ban on the use of coal, shale oil, or synfuels
could be effective in delaying a greenhouse warming. These
policies are also evaluated for their economic and political
feasibility. To put our findings in perspective, alternative,
nonenergy approaches to limiting a greenhouse warming are also
reviewed.
METHODOLOGY
Evaluating the effectiveness of energy policies to reduce
levels of C02 requires the estimation of future patterns of
energy use, the effect of these patterns on CO2 emissions, the
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- Ill -
fate of CC>2 once emitted, and the relationship between levels of
atmospheric CO2 and temperature. Three models were used in the
estimation process:
• a world energy model to project future supply and demand
for alternative fuels and to estimate CC>2 emissions based
on fuel use mixes;
• a carbon cycle model to translate CC>2 emissions into
increases in atmospheric CO2 concentrations; and
• an atmospheric temperature model to estimate changes
in temperature based on increases in atmospheric CO2
and other greenhouse gases.
We used these models to explore a range of possible assumptions
about, energy demand and technologies, atmospheric responses, and
policy alternatives.
We evaluated both medium-run (by the middle of the next
century) and long-run (by 2100) effects, placing greater confi-
dence in the shorter run results. The timing of a 2°C rise is
employed as the measure of medium-run effectiveness. A temper-
ature increase of this magnitude by mid-century would represent
a dramatic departure from historical trends — a rate of increase
equal to roughly 0.3°C per decade, compared with a rise of 0.04°C
per decade during the past 100 years. Over the long run, the
absolute temperature rise in 210U is used as the measure of
effectiveness. Rough estimates of technical constraints, costs,
and the need for political cooperation are used to judge
feasibility.
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- IV -
BASELINE TRENDS
We developed the Mid-range Baseline scenario as a "best
guess" of future energy patterns. Under this scenario/ atmos-
pheric CC>2 levels would reach 590 ppm, or double pre-industrial
levels, by 2060, and a 2°C temperature rise would occur around
2040. By 2100, global warming would approach 5°C. These esti-
mates are particularly sensitive to (1) the assumed temperature
response to a doubling of CC>2f and (2) the rate of increase of
greenhouse gases other than CO2 (i.e., methane, nitrous oxide,
and chlorofluorocarbons). By varying these factors within
reasonable ranges, the projected date of a 2°C warming shifts
from roughly 2015 to 2095. In direct contrast, changes in the
projected costs of alternative fuels or in fuel users' behavior
(i.e., the degree of conservation in response to rising energy
prices and other factors) has almost no effect on the estimated
timing of a 2°C rise in temperature. Specifically, scenarios
reflecting significant reductions in the future cost of nuclear
power and renewable energy, increased conservation, and expanded
electrification have little influence on the date of a 2°C warming,
and only a minor effect on the temperature rise in 2100 (5-10
percent). Similarly, significant reductions in the baseline
costs of shale oil or synfuels fail to accelerate a projected
2°C warming, and estimated temperature in 2100 increases by less
than 5 percent. These findings attest to the substantial momentum
built into temperature trends, due to the effect of other green-
house gases and to the difficulty in changing fuel-use patterns
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- v -
SUMMARY OF FINDINGS
Our analysis of energy and nonenergy policies to slow or
limit a global warming produced the following results:
Only One of the Energy Policies Significantly
Postpones a 2°C Warming
• Worldwide taxes of up to 300% of the cost of fossil fuels
(applied proportionately based on C02 emissions from each
fuel) would delay a 2°C warming only about 5 years beyond
2040.
• Fossil fuel taxes applied to just certain countries or
applied at a 100% rate would not affect the timing of
of a 2°C rise.
• A ban on synfuels and shale oil would delay a 2°C warming
by only 5 years.
• Only a ban on coal instituted by 2000, would effectively
slow the rate of temperature change and delay a 2°C change
until 2055. A ban on both coal and shale oil would delay
it an additional 10 years — until 2065. ;
Major Uncertainties Include Growth of Other Greenhouse
Gases and Temperature Sensitivity of the Atmosphere,
but Not Baseline Energy Scenarios
• Uncertainties concerning the rate of growth of other
greenhouse gases could advance the date of a 2°C warming
by 15 years or delay it by 30 years.
• The plausible range of sensitivity of the atmosphere
to increases in greenhouse gases creates a 35-year band
of uncertainty around the projected year (2040) for a
2°C warming.
• In contrast, alternative energy futures, including sig-
nificant shifts in the relative costs of fuels, changes
in energy demand, and reduced economic growth, cause only
minor (i.e., five years or less) changes in the date of
a 2°C warming.
These findings are illustrated in the following chart. Each bar
represents the number of years the 2°C date is delayed (bar above
line) or advanced (bar below line), compared with the Mid-range
Baseline projections.
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CHANGES IN THE DATE OF A 2° C WARMING
(PROJECTED DATE IN MID-RANGE BASELINE: 2040)
ALTERNATIVE ENERGY
BASELINES
2070
(MID-RANGE CASE) 2040*
2025
5 YRS
0 YRS t|
5 YRS
OTHER
GASES*
30 YRS
HIGH
GROWTH
TEMPERATURE
SENSITIVITY t
25 YRS
HIGH HIGH LOW NO
FOSSIL ELECTRIC DEMAND GROWTH
HIGH
ENERGY POLICIES
25 YRS
15 YRS
5 YRS
LOW
5 YRS < 5 YRS
10 YRS
15 YRS
BAN ON
SHALE
AND
SYN-
FUELS
BAN ON
COAL
BAN ON
COAL
AND
SHALE
300%
WORLD
FOSSIL
FUEL
TAX
100%
WORLD
FOSSIL
FUEL
TAX
•REFERS TO GREENHOUSE GASES OTHER THAN CO2: NITROUS OXIDE, METHANE, AND CHLOROFLUOROCARBONS.
tREFERS TO THE TEMPERATURE RISE IN RESPONSE TO A GIVEN INCREASE IN GREENHOUSE GASES
ONCE AN EQUILIBRIUM HAS BEEN REACHED.
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- vii -
Bans on Coal and Shale Oil Are Most Effective
in Reducing Temperature Increases in 2100
• A worldwide ban on coal (and thus coal-derived synfuels)
instituted by 2000 would reduce temperature change by
30% (from 5°C to 3.5°C).
• Together, a ban on shale oil and coal would reduce the
projected warming in 2100 from 5°C to 2.5°C.
• Bans on shale oil alone or synfuels alone would be
less effective.
• A 100% worldwide tax would reduce warming by less than
1.0°C in 2100.
A Ban on Coal Seems Economically and
Politically Infeasibile
• Though detailed estimates of total costs of a ban on coal
were beyond the scope of this study, initial approxima-
tions based only on asset losses and increases in prices
of alternative fuels suggest that a coal ban is economi-
cally infeasible.
• A worldwide ban on coal also appears to be politically
infeasible. Because the burden would be unevenly distri-
buted (e.g., most of the world's coal is concentrated in
only three nations, and use of coal varies dramatically
between developed and developing nations), worldwide
cooperation required to ban coal is unlikely.
At Best, Nonenergy Options to Limit
Global Warming Are Highly Speculative
• Scrubbing CC>2 emissions from power plants is of limited
effectiveness and prohibitively expensive.
• Capturing ambient CC>2 through massive forestation would
place too great a burden on land, fertilizer, and
irrigation requirements.
• In theory, adding SO2 to the stratosphere might counter-
balance the greenhouse warming effect, but at great cost.
Moreover, the effectiveness and potential adverse environ-
mental consequences of this proposal require much additional
research.
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- Vlll -
IMPLICATIONS OF FINDINGS
The implications of our findings point to action directed
in the following three areas:
Accelerate and Expand Research on Improving Our Ability to
Adapt to a Warmer Climate — This research should focus
on enhancing the positive and minimizing the negative
aspects of a greenhouse warming. It should also address
problems likely to occur during the transitional stage when
social and economic systems are adapted to the consequences
of increased CC>2 and temperature. A key element of this
research must be developing regional climate scenarios that
can be used to evaluate the costs and benefits associated
with possible changes in climate and that can serve as a
baseline against which possible adaptive actions can be
evaluated.
Narrow Uncertainties About the Future Effects Greenhouse
Gases Other Than CO? — Research relating to other greenhouse
gases should focus on developing a better understanding of
the natural and man-made sources and sinks of these gases,
of their interactions with other atmospheric gases, (espec-
ially their effects on atmospheric ozone), and of possible
strategies to mitigate their influence on future global
warming.
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- IX -
Reducing Uncertainty About the Thermal Sensitivity of the
Atmosphere — Narrowing the range of uncertainty regarding
the temperature sensitivity of the atmosphere to increases
in greenhouse gases will depend on expanded modeling efforts.
Cloud formation and ocean systems must be more realistically
represented in climate models, and our ability to use these
models in predicting transient warming effects must be
improved.
Our analysis underscores the need to reduce remaining scien-
tific uncertainties as quickly as possible. Substantial increases
in global warming may occur sooner than most of us would like to
believe. In the absence of growing international consensus on
this subject, it is extremely unlikely that any substantial actions
to reduce CO2 emissions could or would be taken unilaterally.
Adaptive strategies undertaken by individual countries appear to
be a better bet. But for these strategies to succeed, much more
precise and detailed information will be needed on the timing
and regionally disaggregated consequences of a global warming.
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CHAPTER 1
CO? AND THE GREENHOUSE EFFECT; STUDY OVERVIEW "
The scientific community is growing increasingly concerned
about the build-up of carbon dioxide (CC^) in the atmosphere.
Resulting primarily from the use of fossil fuels, CC>2 emissions
may alter the radiative balance of the earth, increasing global
temperature, and dramatically changing global climate. Although
much uncertainty remains concerning the magnitude, timing, and
possible effects of rising levels of CO2, this issue is considered
to be one of the most important facing the scientific community,
and one that raises significant questions for policymakers.
This study explores one particularly important aspect of
the CO2 issue — the potential effectiveness and feasibility of
alternative public actions aimed at limiting or delaying a CO2~
induced rise in temperature. It focuses on policies to reduce
the use of fossil fuels, including energy taxes and bans on the
use of synfuels, shale oil, and coal. It also reviews other
approaches to delaying temperature change. These include removing
CC>2 from flue gases after fuel combustion, sequestering CO2 from
the atmosphere by planting trees, and seeding the atmosphere with
SC>2 to block incoming solar energy. By providing new information
on both energy and nonenergy approaches to modifying the green-
house effect, we hope to focus current and future discussions on
what to do about rising
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1-2
BACKGROUND TO THE GREENHOUSE EFFECT
The "greenhouse theory" — that increases in CC>2 will warm
the earth — was first developed by scientists before the turn
of the century (Arrenhius, 1896). This theory holds that certain
"greenhouse" gases in the atmosphere allow the sun's ultraviolet
and visible radiation to penetrate and warm the earth, but then
absorb the infrared energy the earth radiates back into the
atmosphere. By blocking the escape of this radiation, these
gases effectively form a thermal blanket around the earth. To
rebalance the incoming and outgoing radiation, the earth's
temperature must increase. Based on the current level of CC>2
in the atmosphere, the average global temperature now stands at
288°K, approximately 35°K warmer than it otherwise would be
(Chamberlain, et al., 1982).
Carbon dioxide is the principal greenhouse gas. Methane,
chlorofluorocarbons, and nitrous oxide, along with water vapor,
also exhibit greenhouse properties. Increases in the atmospheric
levels of these other trace gases could add significantly to any
future CC>2-induced global warming.
Since the onset of the industrial revolution, increases in
atmospheric CC>2 levels have been small, but significant. From
1860 to the present, the concentration of CC>2 has grown from
about 270-290 parts per million (ppm) to 339 ppm (Keeling, 1982).
Our increased reliance on fossil fuels is directly responsible
for most of this growth. By burning large quantities of these
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1-3
fuels every year, we are shifting enormous quantities of carbon
— roughly 5 billion metric tons annually — to the atmosphere
from the earth where it had been inactive over millions of years
(Rotty, 1983).
CURRENT UNDERSTANDING OF THE POTENTIAL FOR GLOBAL WARMING
The greenhouse theory assumes that, holding everything else
constant, altering the composition of the atmosphere by adding
large quantities of CC>2 and other greenhouse gases will warm the
earth. While the physical laws underlying the theory are well
established and straightforward, the assumption that all else
will remain constant is not reasonable.
The global climatic system is extremely complex. It consists
of many interrelated components that, in themselves, are only
partially understood. Changing one of these components — in this
case, increasing the quantity of atmospheric greenhouse gases —
will undoubtably have repercussions throughout the natural systems
that determine global climate.
To identify the extent to which increases in CC>2 would raise
atmospheric temperature or, conversely, to isolate the nature
and magnitude of countervailing forces, the National Academy of
Sciences (NAS) convened a study panel chaired by Dr. Jule Charney
in 1979. After reviewing the existing scientific evidence, this
panel concluded that a doubling of pre-industrial atmospheric CC>2
levels would most likely increase global climate 3.0 + 1.5°C
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1-4
(Charney, 1979).* Recognizing that these findings would be
"comforting to scientists but disturbing to policymakers," the
panel further stated:
To summarize, we have tried but have been unable to
find any overlooked or underestimated physical effects
that could reduce the current estimated global warmings...
to negligible proportions or reverse them altogether....
It appears that the warming will eventually occur....
(Charney, 1979)
A second NAS panel, convened in 1982, reexamined these conclusions
in light of more recent research. It concluded: "The present
study has not found any new results that necessitate substantial
revision of the conclusions of the Charney report" (Smagorinsky,
1982).**
Several investigators have projected that CO2 will double
by the middle of the next century (e.g., Anderer, 1981; Nordhaus,
1977). When viewed in the context of historical changes in
temperature, the projected temperature rise must be considered
substantial.
* The NAS panel examined increases in temperature due only to
CO2- Other greenhouse gases could further increase global
warming by 50% - 100% (see Chapter 2).
** Despite reaffirming the first panel's conclusions, consider-
able uncertainty remains. For example, while the second
panel agreed that a temperature rise of 3.0 +_ 1.5°c is the
most likely response to a doubling of CC>2, it hedged this
projection with a footnote that the first panel intended
the true value would fall within this range with only a 50%
probability.
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1-5
Temperature changes of 5.0°C cover the entire temperature range
experienced during the past 125,000 years, which extend from the
last interglacial period to the present one (Mitchell, 1977).
The projected warming induced by increases in CC>2 thus could
equal historical changes in climate in a matter of only 120 years.
The possible magnitude of temperature change tells only part
of the story. The rapid occurrence of this change must be empha-
sized to more clearly put it in historical perspective. Although
the earth has experienced significant changes in temperature,
they generally have occurred over tens of thousands of years and
must be viewed in terms of geologic time, instead of the several
decades during which an equivalent CO2~induced warming is likely
to occur. As a result, we will soon experience climatic trends
that significantly deviate from the past (see Figure 1-1).
Chapter 2 of this report explains in greater detail the
scientific basis and uncertainties surrounding projections of a
greenhouse warming.
IMPLICATIONS OF THE GREENHOUSE EFFECT
Warmer global temperatures are just one aspect of CO2~induced
changes to the natural environment. A rise in sea level, changes
in precipitation and water availability, altered storm patterns
and frequencies, and changes in growing seasons are all signifi-
cant climatic events likely to accompany a greenhouse warming.
Many parts of the world are likely to suffer from these changes,
yet others are likely to benefit.
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1-6
FIGURE 1-1
RANGE OF GLOBAL-SCALE MEAN TEMPERATURE, WITH AND WITHOUT THE
PROJECTED C02 EFFECT
-5
0)
3
TO
I
c
10
Q>
5 -
4
3r-
2
1
Observed past changes
\
Present
Range of natural j
t'ons ;
ic "noise"):
I
I
ID'
9
8
7
6
5
4
3
2
1
0
-1
-2
1850
1900
1950
2000
2050
2100
Source: CEQ (1981). Based on J.M. Mitchell, Jr., (1977) "Some
Considerations of Climate Variability in the Context of
Future CO2 Effects on Global-Scale Climate," in Elliot
and Machta, Carbon Dioxide Effects Research and Assess-
ment Program; Workshop on the Global Effects of Carbon
Dioxide from Fossil Fuels.
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1-7
Given the limited knowledge of specific regional effects
resulting from higher levels of CC>2r it is now impossible to
predict the net effect of such changes. Moreover, the analysis
of ultimate effects must also account for difficulties encountered
during the transitional period when climate is changing, and for
the possibility that some negative effects will be mitigated,
depending on the success and speed of efforts to adapt economic
activity to altered climatic conditions.
POSSIBLE ADVERSE CONSEQUENCES
A warmer climate could dramatically change existing eco-
systems, affect the habitability of many areas of the world, and
alter the relationship between developed and developing nations.
Adverse impacts will result primarily from increases in temper-
ature, changes in precipitation, changes in storm patterns, and
increases in sea level.
A warmer climate will raise sea level by warming and
expanding the oceans, and by melting ice and snow now on land.
By itself, thermal expansion could raise sea level significantly.
Further in the future, this rise may be enhanced by significant
ice melting and discharges from land-based glaciers. Given
current uncertainties, an initial effort to estimate the range
of possible sea level rise concluded that increases of
anywhere from about 48 to 380 cm (2 to 12 ft.) are possible
in the next 120 years (Hoffman, 1983). An increase of
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1-8
of even 48 cm could flood or cause storm damage to many of the
major ports of the world, disrupt transportation networks, alter
aquatic ecosystems, and cause major shifts in land development
patterns.
The consequences of climate change will differ depending on
whether or not adjustments are feasible. For example, changes
in climate will require significant adjustments in agricultural
practices (e.g., breeding new strains of seeds adapted to changed
CC>2 levels and climate) and in land-use patterns (e.g., shifting
away from coastal areas). To the extent that these adjustments
are made in a timely manner, many of the adverse consequences of
a CO2 warming can be minimized. In other situations, however,
adjustments simply may not be feasible and a total loss may result.
For example, despite adjustments to agricultural practices, some
currently productive land may no longer be suitable for farming
because of significant changes in the length of the growing season
or in rainfall patterns. Similarly, if water resource planning
does not anticipate shifts in rainfall patterns, water shortages
could reach catastrophic proportions.
Recent changes in weather conditions experienced throughout
many parts of the world (attributed by some to the El Nino meteoro-
logic phenomenon) give some indication of the economic and social
consequences of dramatic shifts in climate. Initial estimates
place damages due to droughts and floods at over $8 billion and
deaths at over 1,000 (Washington Post, 1983).
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1-9
POSSIBLE BENEFICIAL CONSEQUENCES
In contrast to these negative effects, increases in atmos-
pheric CO2 are likely to enhance photosynthesis and decrease
moisture requirements for plant growth — both of which should
increase agricultural productivity. A global warming could also
improve climate for high latitude areas, increase precipitation
for some parts of the world, and reduce heating costs worldwide.
To a limited extent, these altered conditions, by themselves,
will enhance certain economic activities. For example, without
any changes in agricultural practices, higher CC>2 levels will
enhance the productivity of many crops. However, some plants will
respond to this stimulus more than others. Only by taking steps
to identify and expand the use of those plants that benefit the
most will nations be able to maximize the advantages of higher
levels of
NET EFFECTS AND TRANSITIONAL PROBLEMS
Even areas that directly benefit from or that ultimately
adapt to altered conditions may experience difficulties redirecting
their economies to meet the challenges of rapidly changing clima-
tic conditions. Decisions concerning agricultural practices,
land-use patterns, and coastal structures often assume that cli-
matic conditions will be roughly the same as in the past. For
example, many decisions about tree selection, road and bridge
construction, and 'coastal development have been based on a
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1-10
continuation of historical climate trends during the useful life
of these activities, which is 50 years or more. Future damages
can be minimized only if these assumptions are changed for the
next generation of decisions. Of course, the precision and
detail of the predictions of climatic change must be greatly
improved if they are to be used in public works and resource
planning.
Whether an individual country benefits or is harmed will
depend on its location, its resource and industrial base, and,
most importantly, its ability to prepare and adapt to changing
climatic conditions. If climate dramatically changes, it will
likely affect nearly the entire range of human activity. The
magnitude of these effects, and whether they are positive or
negative, depends to a large extent on how quickly these changes
occur — or on our ability to delay climatic change -- and how
successfully global society anticipates and adjusts to them.
DEFINING THE APPROPRIATE RESPONSE
Given the potential magnitude of the CO2 problem, it is not
surprising that many have raised the question: What can be done?
Are there steps that we can and should take to prevent COo from
rising to some unacceptable level? Or, instead, should we explore
actions aimed at minimizing the costs of adapting to COo-induced
changes? In either case, how soon do we have to act?
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1-11
While there are no simple answers to these questions, a
growing body of experts is calling for action now. For example,
in its 1979 report, the National Academy of Sciences warned against
further delay in responding to the CC>2 problem — "A wait and see
attitude may mean waiting until it's too late" (Charney, 1979).
Along similar lines, a report by the President's Council on
Environment Quality concluded: "If a global response to the CC>2
problem is postponed for a significant time, there may not be
time to avoid substantial economic, social, and environmental
disruptions once a CC^-induced warming trend is detected"
(CEQ, 1981).
Calls for an immediate response have also been voiced at
Congressional hearings, in newspaper editorials, and in news
magazines across the nation. Such calls for action are not
surprising, given the magnitude of the potential climatic changes
that might accompany further increases in atmospheric CC^. In
the minds of many, concern about these changes far outweighs
remaining uncertainties surrounding their exact nature and timing.
Two very different strategies could be employed to respond
to this call for action.* The first approach is an adaptive
strategy. Rather than seeking to limit CC>2 increases, it focuses
* For another discussion of these strategies, compare "Reduction
at the Source," Scroggin and Harris, and "A More Feasible Soical
Response," Lave, both in Technology Review, Nov./Dec. 1981.
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1-12
on steps that would minimize the negative and maximize the posi-
tive effects of CO2- For example, land development would be
directed in-land to avoid damage from the rise in sea level, and
agricultural practices would be shifted to take advantage of
increases in photosynthesis.
In contrast, a prevention strategy seeks to delay or limit
the build-up of greenhouse gases in the atmosphere. Since CC>2
results primarily from the burning of fossil fuels, this strategy
necessarily implies a shift in current patterns of energy use.
These two alternatives are, of course, not mutually exclusive.
By limiting use of fossil fuels and, slowing the rise of CC>2, we
would be buying more time to design and implement adaptive actions.
Given the large uncertainty in projecting likely climatic
changes and resulting socioeconomic effects, any comparison of
the costs and benefits of these alternative approaches would now
be little more than guesswork. Although researchers have called
for development and evaluation of regional scale scenarios that
could be used for analyzing the impacts of CC>2, with few excep-
tions, these projects remain as items on future research agendas
(Kellogg, 1981). Only after initial estimates are developed of
the economic effects of rising CC>2 levels will researchers be able
to quantitatively compare the desirability of adaptive versus
preventive approaches to dealing with the CO2 problem.
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1-13
Nevertheless, by focusing specifically on the potential
effectiveness of alternative policy actions aimed at delaying or
limiting a rise in atmospheric CC>2 levels, we can provide useful
insights into whether "adaptation or prevention" or some combina-
tion thereof is the appropriate response. This study contributes
to that goal.
EVALUATING THE PREVENTION STRATEGY
Two general approaches to slowing or limiting CO2 increases
have been mentioned — one that relies on altering patterns of
energy use, and one that employs nonenergy strategies. The first
approach attempts to mitigate the CC>2 problem indirectly. Burning
less coal, oil, and gas, would slow the rate of increase in CC>2
emissions. Shifting away from fossil fuels, however, would entail
a radical change in the energy foundation upon which current
economic activity rests. Under the second approach, CC>2 is
captured either before or after emission to the atmosphere (i.e.,
removed from flue gases using scrubbers or sequestered from the
ambient air using trees), or the amount of incoming solar radia-
tion absorbed by the earth is reduced via novel schemes. Chapter
6 of this analysis examines the effectiveness, costs, and feasi-
bility of these options.
Altering fuel-use patterns has been the most commonly dis-
cussed approach to preventing a global warming. However, such
an approach carries with it several potentially severe effects.
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1-14
These include:
• reducing the value of the vast global fossil fuel
resources;
• making prematurely obsolete some portion of the capital
infrastructure that supports current patterns of produc-
tion, transportation, and use of fossil fuels; and
• increasing the percentage of total capital invested in
the energy sector to pay for more expensive energy
alternatives.
The magnitude of these economic disruptions would depend on
how rapidly alternative energy sources must substitute for fossil
fuels. The acceleration of the rate at which fossil fuels are
displaced will, in turn, depend on the shift to nonfossil fuels
due to market forces alone, and on the rate of acceptable climatic
change. Furthermore, the shift away from fossil fuels perhaps
could be instituted more gradually and therefore less expensively
if energy policies were adopted now rather than several decades
later.
METHODOLOGICAL APPROACH
Determining the effectiveness and feasibility of shifting
energy consumption to prevent or limit a rise in temperature
involves modeling the complex interaction among energy technolo-
gies and resources, world economies, the carbon cycle, and atmos-
pheric physics. For this analysis we used three models: the
world energy model of the Institute for Energy Analysis, the
carbon cycle model of the Oak Ridge National Laboratory, and
the atmospheric temperature model of the Goddard Institute for
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1-15
Space Studies. By integrating these models, we developed a method
for (1) estimating the likely global warming for a range of alter-
native energy futures, and (2) evaluating the effectiveness of
alternative policies to delay or limit that warming. Chapter 3
explains each of these models and their underlying assumptions in
greater detail.
We evaluated the nonenergy strategies less rigorously,
although still quantitatively. Using simple conceptual models
and extrapolating from literature reports, we made first-order
estimates of the effectiveness and feasibility of each of the
three strategies.
BASELINE SCENARIOS
The energy scenarios examined as part of this study start
with a baseline that assumes mid-range estimates for alternative
fuel costs, economic growth, and other key parameters. In addi-
tion, alternative future scenarios examine CC>2 and temperature
changes that would result if the costs of nonfossil alternatives
(e.g., nuclear or solar) prove to be lower than expected, if
projections of energy conservation or future energy demand prove
to be high, or if, on the other hand, mid-range estimates of the
costs of new fossil fuel technologies prove to be low. Together,
these alternative baselines provide a range of possible energy
futures against which various policies aimed at reducing fossil
fuel use can be examined.
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1-16
POLICY OPTIONS
Two basic energy policy options are examined in Chapter 4 of
this study:
• fossil fuel taxes based on the relative quantity of
carbon emissions from each energy source; and
• bans on future worldwide consumption of coal, synfuels,
and shale oil in various combinations.
The CO2 tax option is first applied to the United States to
determine the effects of unilateral actions, next to OECD coun-
tries, and finally on a global-scale to determine the need for
international cooperation. All fuel ban policies are applied
worldwide.
Chapter 5 discusses the nonenergy policy options for miti-
gating a greenhouse warming: CO2 emission controls, forestation
programs for sequestering atmospheric C02, and injecting SO2 into
the stratosphere to increase atmospheric reflectivity. Each option
is assessed for effectiveness and feasibility.
MEASURES OF EFFECTIVENESS
The effectiveness of each energy policy option is measured
in terms of delaying or limiting temperature increases. If a
policy is not effective, costs and future feasibility are of
little significance.
The primary measure of effectiveness is the number of years
a particular option delays a temperature increase of 2°C. A 2°C
temperature rise was selected because it represents a global
warming significantly beyond the historical change for any 120
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1-17
year period, and one guaranteed to produce substantial climatic
consequences. As noted earlier in this chapter, 2°C is signifi-
cant in comparison with temperature changes that produced ice ages.
Moreover, a 2°C change by the middle of the 21st century would
produce an average warming of about 0.3°C per decade. During
the past 100 years, the average change has been only 0.04°C per
decade. In addition, temperature serves as a useful indicator
of changes in overall climatic conditions (e.g., storm frequency,
precipitation, wind direction), which are largely determined by
spatial temperature gradients.
A secondary measure of effectiveness is how much the esti-
mated temperature in the year 2100 is lowered. Because these
estimates span a far longer time frame, the conclusions they
support are substantially more speculative than conclusions based
on a 2°C temperature change.
Earlier studies examining possible options to reduce the rise
in CO2 focused primarily on the steps necessary to prevent a doubling
of pre-industrial levels of atmospheric CO2 (Nordhaus, 1977). In
addition, most climate models have been employed to estimate the
temperature effects of doubled atmospheric CC>2 • The different
focus here — the timing of a 2°C temperature change rather than
a doubling in CO2 — offers several advantages. First, it allows
other greenhouse gases and their effects on temperature to be con-
sidered as part of the analysis. Second, it allows the range of
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1-18
current uncertainty in predicting temperature change (3.0 +_ 1.5°C)
for doubled CC>2 levels to be incorporated into the analysis.
Third, it highlights the significance of time lags between CC>2
and temperature rises. Finally, it shifts attention away from
what has become simply a convenient convention for analysts to a
more meaningful measure of the greenhouse effect — global
temperature.
Measures of effectiveness employed in the analysis of non-
energy strategies are less specific, largely because our findings
are extrapolated from other studies. In general, we compared
either projected annual reductions in CC>2 with current emission
rates, or projected reductions in temperature with expected
CC>2-induced increases.
MEASURES OF FEASIBILITY
If a policy is to prove desirable, it must be technologically,
economically, and politically feasible, in addition to being
effective. Unlike effectiveness, no simple and direct measure
exists to determine the feasibility of the policy options examined
in this study. The world energy model used in the study does not
contain a sophisticated enough structure of regional economies nor
complete enough representation of cost factors in the energy sector
to provide a reliable basis for evaluating economic feasibility.
In addition, considerations of international cooperation fall far
beyond the model's scope to support an evaluation of political
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feasibility. As an alternative analytical approach, Chapter 6
of this study uses a series of examples to illustrate the potential
economic and political ramifications of adopting policies that
limit fossil fuel use.
FINDINGS AND CONCLUSIONS
Finally, Chapter 7 brings together the previous discussions
of effectiveness and feasibility and presents a summary of findings
and conclusions. It also highlights critical uncertainties and
areas for future analysis.
-------
CHAPTER 2
SCIENTIFIC BASIS FOR A GREENHOUSE WARMING
This chapter discusses the scientific evidence linking
increases in carbon dioxide and other greenhouse gases to climatic
change. Although many aspects of this linkage need to be further
resolved and clarified, much is now known from past and ongoing
research efforts.
ROLE OF GREENHOUSE GASES
The temperature of the earth is determined by a balance be-
tween the radiation it absorbs and emits. By reflecting or
absorbing and then reradiating certain wavelengths of the sun's
radiation as it enters the atmosphere, some atmospheric consti-
tuents reduce the amount of energy reaching the earth's surface
and thus decrease global temperature, volcanic aerosols and
certain forms of particulate matter are examples of atmospheric
components with these characteristics.
Other atmospheric components, commonly referred to as green-
house gases, have the opposite effect. These gases allow visible
and ultraviolet radiation from the sun to penetrate to the planet's
surface, but absorb some of the infrared energy that is reradiated
from the earth. In a sense, greenhouse gases form a "thermal
blanket" around the earth. As these gases increase in concentra-
tion, incoming radiation temporarily exceeds that leaving the
earth. In reestablishing a radiation balance, the earth-atmos-
phere system increases in temperature.
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2-2
Several gases found in the atmosphere exhibit the properties
of a greenhouse gas. Carbon dioxide is the most abundant and best
known. Other potentially significant greenhouse gases include
methane, nitrous oxide, and chlorofluorocarbons. In addition,
water vapor demonstrates a sizable greenhouse effect. Thus,
increasing levels of water vapor from evaporation and melting,
which will accompany a CO2~induced global warming, further
enhance the greenhouse effect.
Because of the complexity of the natural systems involved,
experiments to further test and clarify the greenhouse effect
are not feasible. In fact, the only meaningful field experiment
that could be conducted is the uncontrolled one now taking place
as we burn large quantities of fossil fuels. The nature of this
experiment was best expressed in an early article written by
Revelle and Suess in 1957:
....Human beings are now carrying out a large-scale
geophyscial experiment of a kind that could not have
happened in the past, nor be repeated in the future....
The experiment, if adequately documented, may yield a
far-reaching insight into processes determining weather
and climate....
The challenge facing researchers and policymakers today is to
determine a course of action in which we maintain the flexibility
to respond in a timely and effective manner as this ongoing
experiment unfolds.
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2-3
There are, however, at least two approaches to obtaining
insights into how increases in greenhouse gases might affect
atmospheric temperature and climate. First, we can investigate
the relationship between the chemical composition and temperature
of the atmosphere surrounding different planets for clues of how
greenhouse gases influence temperature. Second, global climate
models can be manipulated to simulate the climate of a world
with higher levels of atmospheric CC>2.
COMPARISONS WITH OTHER PLANETS
Recent space probes to other planets have provided informa-
tion on atmospheric composition and temperature that substantiates
the greenhouse theory. From them, we have learned that the
atmosphere of Venus is composed of approximately 97 percent carbon
dioxide, and its surface temperature is about 700°K. In contrast,
the atmosphere of Mars contains only a small amount of CC>2 and
therefore does not block the escape of infrared radiation. Its
temperature is approximately 220°K. The earth's atmosphere
contains about 0.03 percent CC>2 (and more water vapor than Venus or
Mars),and its observed temperature is 288°K.
Taking into account differences in solar radiation received
by these planets and differences in their albedos (i.e., ground
and cloud cover, which influences the reflectivity of the planet's
surface), their estimated surface temperatures based on the hypo-
thesized effects of greenhouse gases are very close to observed
values. Although this analysis by analogy falls far short of
verifying estimates of future atmospheric warming on earth, it
does provide fundamental evidence supporting the validity of
the greenhouse theory.
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2-4
EVIDENCE FROM CLIMATE MODELS
Efforts are now under way to better understand the rela-
tionship between atmospheric composition and temperature on our
planet. The principal approach involves developing mathematical
models of the geophysical conditions that produce global climate.
To various degrees of complexity, these models simulate radiation
from the sun as it penetrates the various layers of the atmosphere,
the distribution of energy over the earth's surface, the radiative
effects of greenhouse gases, the effect of the earth's albedo,
reradiation of energy from the earth back into the atmosphere,
and the flux of heat from the atmosphere to the earth and into
the oceans -- all of which interact to produce circulation and
climate patterns within our atmosphere.
In effect, the more elaborate three dimensional general cir-
culation models (GCMs) represent, in simplified mathematical form,
the physical processes that combine to create short-term weather
patterns. These patterns, over time, produce climate. The most
advanced of these models provide output for time intervals as
short as 15 minutes and for relatively small areas (thousands of
square kilometers). In contrast, relatively simple one-dimensional
radiative-convective models (referred to as 1-D RC models) can
be used to calculate long-term trends in globally averaged temper-
ature changes.
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2-5
Despite the complexity of the tasks, climate models have
demonstrated considerable accuracy. For example, a National
Academy of Sciences (NAS) review of these models concluded that
attempts at recreating existing climate patterns have produced
"a reasonably satisfactory simulation of the present large-scale
climate and its average seasonal variation" (Smagorinsky, 1982).
In addition, consistency has been demonstrated both among different
GCMs, and between GCMs and 1-D RC models. These models have also
successfully recreated past climates.
In 1979, and again in 1982, NAS reviewed the state-of-the-art
in climate modeling. It concluded that temperature could rise
3.0 _+ 1.5°C for a doubling of preindustrial atmospheric CO? levels
(Charney, 1979; Smagorinsky, 1982). These conclusions were based,
in part, on the experimental results of two GCMs that pre-
dicted a 2°C change (Manabe, 1980) and close to a 4°C increase
(Hansen, 1983) with a doubling of CC>2 •
The differences in these results can be explained by examining
how each of the models treats various components and feedbacks of
the climate system. Specifically, the Hansen model shows a small
increase in mean cloud height and a slight decrease in cloud
cover for runs with doubled CC^. Both of these feedbacks increase
convective warming, and in so doing increase temperature approxi-
mately 1.3°C. In contrast, the Manabe model holds cloud altitude
and cover constant. The two models also differ in their treatment
of heat transport by the oceans and changes in sea ice.
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2-6
Climate models provide an essential analytical tool for
understanding the potential changes in climate brought about by
increases in greenhouse gases. Their usefulness is likely to
increase over time as the models are further refined and as
existing uncertainties are reduced. Critical areas requiring
more sophisticated treatment include the storage and transport
of heat by the oceans, the role of clouds in determining climate,
and possible changes to clouds as the earth warms. To improve
these components of climate models, additional observational
efforts will be required to close existing gaps in data bases.
The deficiencies in and disagreements among climate models
described above should not obscure the large amount of useful
information and the extent of agreement that exists in this
field. In the absence of unambiguous empirical evidence of the
relationship between atmospheric CC>2 and temperature, climate
models provide the next best tool for characterizing this
relationship.
TIMING OF TEMPERATURE RISE
To date, GCMs have not been used to estimate the timing of
global warming or climatic change. Instead, these models have been
run assuming that atmospheric levels of C02 have doubled and that
temperature has reached its equilibrium level.
The actual nature of the warming process will be quite dif-
ferent. Additional emissions of CC>2 will cause atmospheric con-
centrations of this gas to increase gradually and continually.
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2-7
Futherraore, due to the capacity of the ocean to absorb and dis-
tribute the heat produced by the greenhouse effect, temperature
rises should lag CO2 increases by several decades (Smagorinsky,
1982). A proper accounting of the transitional period, as CC>2
levels increases, must consider nonequilibrium conditions and
time lags due to the carbon cycle and heat exchange processes.
THE ORIGIN AND EXCHANGE OF CO2 IN THE ENVIRONMENT
Unlike the uncertainty surrounding climate model estimates,
the trend in atmospheric CCU levels since the Industrial Revolu-
tion is well documented. Around 1890, at the beginning of the
industrial period, atmospheric concentrations are estimated to
have been in the 280 to 290 ppm range (Barnola, 1983). Precise
measurements of atmospheric CO2 were initiated at Mauna Loa, Hawaii,
in 1958 (see Figure 2-1). At that time, these readings registered
CO2 levels of 315 ppm or approximately a 12.5 percent increase
since the 1890s.
The most recent readings place CC>2 levels at 339 ppm, an
additional 7 percent increase in just over 20 years (Keeling,
1982). This increase is due in large part to the approximately
160 gigations of CC>2 emitted from fossil fuel consumption since
1900 (Rotty, 1983). Although not all of those emissions have
remained in the atmosphere — considerable controversy surrounds
this question -- a large percentage has.
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2-8
FIGURE 2-1
MONTHLY ATMOSPHERIC CARBON DIOXIDE CONCENTRATION AT MAUNA
LOA OBSERVATORY*
E
Q.
o
c
a>
u
O
o
CM
O
O
340 -
336
332
328
324
320
316
312
j I
I
1958 1960 1962 1964 1966 1968 1970 1972 1974 1976 1978 1980
*Seasonal effects have been normalized.
Source: CEQ (1981), based on data derived from Keeling, Scripps
, Institute of Oceanography.
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2-9
THE CARBON CYCLE; PAST, PRESENT AND FUTURE
Figure 2-2 depicts the stocks of carbon in each natural
reservoir and the annual flows that take place among reservoirs.
Taken together, these stocks and flows constitute the carbon cycle.
Carbon distributed through this cycle plays an important role in
the ecological balance of the atmosphere, biosphere, and oceans.
Fossil fuels are merely preserved forms of carbon (and other
elements) previously created in the biosphere. Thus, burning
fossil fuels simply redistributes carbon from one reservoir to
another. In effect, however, it represents a substantial new
flow due to man's activities alone. Carbon stored over hundreds
of thousands of years in fossilized forms may be released into
the atmosphere in a matter of a few centuries.
Carbon also enters the atmosphere through deforestation.
Exact estimates of the magnitude of the flow vary because of a
lack of consensus regarding the amount of carbon stored in the
soil and rivers, and the countervailing rates of deforestation
and reforestation. Early estimates suggested that changes in
land-use patterns released as much as 20 gigatons of carbon
annually during this century (Woodwell, 1978). Recent estimates
have lowered that figure considerably, with some researchers now
suggesting that changes in land use offset each other (defore-
station and reforestation), resulting in no net increase in atmos-
pheric carbon (Olson, 1982).
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2-10
FIGURE 2-2
EXCHANGEABLE CARBON RESERVOIRS AND FLUXES
Atmosphere
711 (335 ppm of C02)
'
l t I
'
5 56 56 2-3 90 90
I I
12,000
(7,500
ultimately
recoverable)
1,760
1
, ,
'
Fossil fuels Terrestrial
and shales biosphere
.
580
38,400
-
Surface
Intermediate
and deep
Oceans
Reservoirs in 10 metric tons
Fluxes in 10 metric tons/year
Source: CEQ (1981), as shown in World Meteorological Society,
"Report of the Scientific Workshop on CO2," Report
474, Geneva 1977.
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2-11
FRACTION OF CO? FROM FOSSIL FUELS THAT REMAINS AIRBORNE
The amount of carbon emitted from fossil fuels retained in
the atmosphere is critically important to the pace and magnitude
of global warming. This percentage is called the airborne frac-
tion or retention ratio. If the airborne fraction is high, more
CO2 emitted into the atmosphere will remain there, and climatic
change is likely to occur sooner than if it is low. Scientists
have used recent data on worldwide fuel usage, rates of defores-
tation and reforestation, and increases in atmospheric CO2 to
obtain an estimate of 0.4-0.6 for the historic airborne fraction
(Clarke, 1982).*
In the future, an increasing percentage of CO2 from fossil
fuel emissions is likely to remain in the atmosphere. This is
based on the belief that the top layers of the ocean, which serve
as the primary repository of carbon not retained in the atmosphere,
will become saturated. Moreover, as temperatures rise, the capa-
city of the ocean to absorb C02 is diminished. On the other hand,
rising CO2 may stimulate plant growth thus enhancing the biosphere's
carbon retention capacity.
* Considerable uncertainity exists concerning the historic atmos-
pheric levels of C02. Researchers are unsure of the contribu-
of past deforestation. To the extent that deforestation has
been significant, its contribution to airborne CO2 would be
higher than previously estimated, and the fraction of fossil
fuel emissions retained in the atmosphere consequently lower.
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2-12
Given these uncertainties, one recent estimate of the likely
future airborne fraction concluded that it would fall somewhere
within the 0.38 - 0.72 range. If existing carbon cycle models
are accurate, the actual fraction is likely to be closer to the
higher level of that range (Oeschger, 1983).
INCREASES IN OTHER GREENHOUSE GASES
Human activities may also be responsible for increasing the
atmospheric content of other greenhouse gases. These gases are
principally nitrous oxide, methane, and chlorof luorocarbons.
Although they have generally received less attention and are
present in the atmosphere in smaller concentrations than CO2
(and are sometimes called "trace gases"), their increase may
contribute significantly to global warming.
NITROUS OXIDE
Nitrous oxide (^O) emissions result primarily from biological
dentrif ication processes in soil and in the oceans. By increasing
the use of nitrogen fertilizers and by adding nitrogen-rich sewage
to water bodies, we are indirectly adding nitrous oxide to the
atmosphere. Measurements of ^0 concentrations from 1970 to 1980
show an increase of 6 parts per billion (ppb) to a level of 295
ppb (Lacis, 1981). Estimates suggest that a doubling of nitrous
oxide would directly increase temperature by 0.30-0.44°C ( Donner
and Ramanathan, 1980; Wang and Sze, 1980).
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2-13
In addition, increases in N2O may indirectly contribute
to an even greater warming. Through various reactions with
other gases in the atmosphere, greater amounts of ^O may lead
to higher levels of ozone in the lower stratosphere and upper
troposphere. Wang and Sze have calculated that the resulting
indirect greenhouse warming could raise temperature another
0.18°C for a total increase of 0.48-0.62°C due to a doubling
of N2O (Wang and Sze, 1980).
As greater demands are placed on world food supplies,
increased use of nitrous oxide-producing fertilizers is likely.
However, because the natural sources and sinks of this trace gas
are not well understood, more research is required before reli-
able projections can be made of future levels.
METHANE
Methane (CH^), is a second important trace greenhouse gas.
The known sources of CH4 are anaerobic fermentation in rice fields
and swamps, and enteric fermentation from termites, cows, and other
animals. As the need for food from livestock and rice fields
increases over time, atmospheric levels of CH^ are likely to
increase. In addition, increases in carbon monoxide (from fuel
combustion) in the troposphere will lower the concentration of
compounds that destroy methane. Based on current estimates of a
2 percent per year increase in concentration, by the middle of
the next century CH4 could increase global warming by about 0.2-
0.3°C (Lacis, 1981).
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2-14
Future increases in methane could, however, be far higher
than the estimated 2 percent per year of the recent past. As
the earth warms, extensive peat bogs containing as much as 2000
gigatons of CH4 in the form of methane hydrates now frozen in
northern latitudes may thaw, releasing considerable quantities
of this gas into the atmosphere. While much of this methane is
buried 250-1,000 meters under the ground and therefore, unlikely
to be released for several centuries, a contribution of eight
gigatons per year from methane nydrates under shallow water is
possible within the next 100 years (Bell, 1982).
CHLORQFLUOROCARBQNS
Entirely a product of human activity, chlorofluorocarbons
have only recently appeared in significant quantities in the
atmosphere. Although the shift away from gas-propelled spray
cans in many countries reduced one important source of CFCs,
they are still used in refrigeration equipment and insulated
packaging materials.
Based on the known rates at which CFCs are destroyed in the
stratosphere, one study estimated that the direct effects of CFCs
should increase temperature by approximately 0.3°C if annual
production were maintained at 1973 levels (Wang and Pinto, 1980).
This estimate is probably high, since CFCs reduce the concentration
of ozone, another greenhouse gas. On the other hand, future emissions
of CFCs may be higher or lower than 1973 levels depending on
the effects of the U.S. ban on aerosol propellants, and the extent
to which a ban is applied to other uses and in other countries.
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2-15
COMBINED TEMPERATURE EFFECTS; 1970-80
Researchers at the Goddard Institute for Space Studies used
a one-dimensional radiative-convective model to estimate the
temperature increase from the rise in CC>2 and other greenhouse
gases during the 1970s. They assumed the temperature rise for a
CO2 doubling was 2.8°C. For this ten-year period, they found
that temperature increased a total of 0.24°C. Of that increase,
0.14°C was attributed to a 12-ppin rise in CO2«
The researchers attributed the remaining 0.10°C to the other
greenhouse gases (N2O, CH4, and CFCs) included in their analysis.
Given the uncertainties in their analysis, they concluded that
the other greenhouse gases were responsible for an additional
50-1QO percent of the temperature rise which resulted from in-
creases in atmospheric CC>2 alone (Lacis, 1981). (See Figure 2-3.)
Other investigators have reached similar conclusions (Ramanathan,
1980; MacDonald, 1982; and Chamberlain, 1982).
POSSIBLE EFFECTS OF A WARMER EARTH
If climate models prove accurate, changes in world climate
are likely to occur at an unprecedented rate. All human activi-
ties are likely to be in some way affected. Farming, transpor-
tation, coastal habitation, and the provision of water supplies
are the most obvious. Some nations are likely to benefit from
changes in climate; others will suffer. The same dichotomy will
generally be true for areas within countries.
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2-16
However, even the areas that will benefit from changes in
climate may experience difficulties during a transitional period.
For example, if precipitation were to increase in the Colorado
Basin, the Southwest would certainly benefit in the long run.
But, these benefits could only be fully realized if water storage
and control facilities were constructed to accommodate different
monthly patterns of precipitation and runoff. The 1983 flooding
and resulting economic losses in the Colorado Basin are a case
in point.
Estimates of what the world's climate will be like if CC^-
induced increases in global temperatures occur have been derived
primarily from two sources: paleoclimatic evidence and general
circulation models. Although both of these sources have their
shortcomings, they provide useful insights into possible regional
climatic changes accompanying different levels of a global warming.
RECONSTRUCTING PAST CLIMATES
Paleoclimatic studies attempt to reconstruct historical
climatic conditions using a variety of methods, including analysis
of tree rings and ice core samples, and carbon dating techniques.
By piecing together various clues, paleoclimatic analysis provides
useful indications of past regional climatic conditions when global
average temperature was warmer.
-------
2-17
FIGURE 2-3
TEMPERATURE INCREASES FOR SEVERAL
GREENHOUSE GASES (1970-80)
0.2
to,
0.0
Equilibrium Greenhouse Warmings
Of Gases Added in I970's
0.14
Sum = 0.10
0.034
0.016
0.020
C02 CH4 N20 CCI2F2 CCI3F
(•HZppm) (tlSOppb) (+6ppb) (-H90pp!) (+I35ppt)
Equilibrium greenhouse warmings for estimated 1970-
1980 abundance increases of several trace gases, based on
climate model with sensitivity ~3°C for doubled C02
SOURCE: Lacis, 1981
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2-18
One important advantage of this approach is that interactions
within the complex systems that determine climate can be examined
as a whole. Unlike experiments using climate models, this approach
includes all factors that influence climate.
It does have its drawbacks, however. Like most field experi-
ments, it is impossible to control for individual variables. All
we generally know about the time period being studied is that
global temperature was warmer. Often we lack information required
to fully understand the cause or causes of warmer climates in the
past. Without this knowledge, we must assume that, whatever
forces produced the climate, the effects are similar to those
caused by increases in greenhouse gases. Also, the record is far
from complete; estimates are missing for many regions at various
points in time.
An additional problem in using paleoclimatic studies to pre-
dict future climate patterns arises because of past shifts in
sea level, in the location and size of mountains, and in other
geomorphological features that significantly influence regional
climatic patterns.
Despite these drawbacks, paleoclimatic studies can be a
useful analytic tool:
• to show that significant changes in local conditions
(e.g., an ice-free Arctic) have accompanied relatively
small shifts in past climates; and
• to identify relationships between global conditions
and local phenomena, and to assist in filling in
details concerning the possible range of impacts
accompanying a global warming.
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2-19
Within the range of possible CO2~induced temperature changes
reported by the NAS (3.0 +_ 1.5°C), several geologic periods have
been identified as possible climatic analogies. An extensive
analysis of these periods has been conducted by Herman Flohn
as part of his work for the International Institute for Applied
Systems Analysis.
Flohn examined the early Middle Ages, about 1,000 years ago,
as an example of a time when global temperatures exceeded current
temperatures by approximately 1°C. Using paleoclimatic techniques,
Flohn found that the treeline during this period had advanced
considerably farther north in Europe and Canada, that Vikings had
settled on southern Greenland, and that frequent droughts affected
Europe.
If the average global temperature increases by 2.5°C, Flohn
suggests regional climatic conditions might be similar to those
experienced during the last interglacial period, 120,000 years
ago. During this period, the oceans were 5-7 meters higher than
today's. As a result, the sea substantially inundated the shore-
lines of Europe and western Siberia, and Scandinavia became an
island.
Finally, Flohn examined the time just before the current
glacial-interglacial period, approximately 10 million years ago,
when the global temperature was 4°C warmer. During this period,
evidence suggests that the Arctic was ice-free, while the eastern
Antarctic continent still remained covered by glaciers. The
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2-20
resulting imbalance between an ice-free Arctic and an ice-bound
Antarctic dramatically affected regional climatic patterns. It
caused the arid areas of the Southern Hemisphere to expand toward
the equator, and it extended the arid belt in the Northern
Hemisphere. In general, Flohn predicts that a 4°C warming would
shift the earth's climatic zones northward by 400-800 kilometers.
MODELING FUTURE CLIMATES
Although the results of GCMs are far more accurate when dis-
cussed in terms of global averages, several broad conclusions about
regional climatic changes can be drawn from recent experiments.
First, because of melting ice, increased water vapor, and
the resulting change in the earth's albedo, far more dramatic
temperature changes will occur at the poles than at the equator.
For example, where average global temperatures are estimated to
increase by 3°C, the projected change at the poles is 10°-12°C,
and less than 3°C at the equator. Since the temperature differ-
ential between the equator and the poles is a primary driving
force behind regional weather patterns, a change of this magnitude
could dramatically alter current weather conditions.
A second conclusion based on GCM experiments involves shifts
in precipitation patterns. While it is not clear exactly which
areas will become dryer or wetter, significant departures from
current patterns are projected. Overall, it appears likely that
both evaporation and precipitation will increase worldwide
(Smagorinsky, 1982). Preliminary results from region specific
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2-21
climate modeling suggests that time patterns of precipitation
and evaporation may be far different as well (NASA, 1983). Major
changes in monthly precipitation, runoff, and soil moisture would
hold profound implications for agriculture and water resources
planning.
DETECTING A FUTURE GREENHOUSE WARMING
The greenhouse theory, with GCM experiments and paleoclimatic
studies in support of it, offers convincing evidence for the
likelihood and potential impact of changes in climate induced by
CC>2 and other greenhouse gases. However, despite the useful
information produced by experiments and field studies, much
uncertainty remains.
Given the complexity of the climatic system, detecting a
change in global climate and attributing it to increases in
atmospheric greenhouse gases is difficult. Yet, because of the
potentially high costs and large-scale disruptions involved in
responding to the threat of climatic change, policymakers.seek
a clear signal that increases in CC>2 and other gases are directly
responsible for warmer temperatures. Simply detecting a future
warming trend will not be enough. It must be convincingly attri-
buted to the greenhouse effect.
As a prelude to this future task, recent efforts have been
aimed at explaining the historic variability in climate and at
isolating that portion that might be attributed to rising levels
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2-22
of greenhouse gases. These efforts have focused on identifying
the effects on temperature of various factors, including increases
in greenhouse gases, the frequency of volcanic eruptions, and
changes in solar radiance.
Hansen and his associates used a one-dimensional model to
isolate the effects of CC>2 — compared with those of other factors
— on global warming experienced since 1880 (Hansen, 1981). As
Figure 2-4 indicates, estimates of atmospheric temperature due
to CC>2 alone do not match observed temperatures very well. With
the addition of the changes in volcanic activity and solar radiance
during this period, the fit improves substantially. Hansen1s
study suggests that since the 1880s, CC>2 increases are responsible
for a 0.4°C increase in temperature.*
This analysis is one of the first attempts at developing a
better understanding of the variations in historical temperatures.
Only by isolating CO2~induced changes from other factors affecting
temperature will scientists be able to develop a conclusive case
in support of global warming due to CC>2 and other greenhouse gases.
SUMMARY
This chapter highlighted evidence both of the potential
magnitude of a greenhouse warming and of the critical importance
of resolving existing uncertainties. There is no doubt that
* A comparable method has been used with similar results by
Gilliland (1982) and Budkyo, et al. (1969).
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2-23
FIGURE 2-4
MODELED VERSUS OBSERVED TEMPERATURE TRENDS
Observotions
Model
CO? + Volcanoes
+ Volcanoes + Sun
I860 1900 1920 1940 I960 1980
Global temperature trend computed with a climate
model with sensitivity 2.8°C for doubled C0£ and an
exchange rate K - 1.2 cm2 s"1 between a 100-m mixed layer
ocean and the thertnocline.
Source: Hansen (1981).
-------
2-24
atmospheric C02 levels have increased and will continue to rise
as long as the world remains dependent on fossil fuels. Models
that estimate the climatic effects of this change in atmosphere,
along with increases in other greenhouse gases, are by no means
exact, but provide strong evidence of the likelihood of unprece-
dented rates of temperature increases during the next 120 years.
Based on the strength of what we now understand about the green-
house effect, and the social and economic implications of such
climatic change, extensive research efforts aimed at addressing
the remaining unknowns and at evaluating response options appear
to be warranted.
-------
CHAPTER 3
METHODOLOGY FOR PROJECTING
FUTURE ENERGY AND CO? SCENARIOS
Increases in CO2 will depend on both the total amount of
energy demanded and the mix of fuels employed to satisfy energy
demands. The importance of fuel mixes is reflected by differences
in the amount of CO2 emitted by alternative fuel types, from a
high of 47.6 terragrams of carbon/EJ (1.02 million tons/quadrillion
Btus) for shale oil to zero net emissions for biomass, solar, and
nuclear fuels. Thus, two basic energy strategies for limiting or
slowing the rise of CO2 present themselves—reduce the total
demand for energy, and shift the fuel mix toward fuels with low
CO2 emission coefficients.
To evaluate the effectiveness of energy-based policies in
slowing or limiting the rise in atmospheric C02» we developed a
methodology for projecting patterns of energy use, estimating
future CO2 emissions, and translating emissions into atmospheric
CO2 concentrations and temperature increases. This methodology
relies heavily on a set of computerized models for manipulating
data and simulating relationships. The primary components of
the methodology and the key characteristics of the individual
models are depicted in Figure 3-1.
This chapter describes each step in the method including
the key features of each model. It emphasizes the assumptions
and parameter values used to initialize model runs, since the
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3-2
FIGURE 3-1
STUDY METHODOLOGY
Project Energy Use and CO? Emissions
• Estimate Changes in Population
and Productivity
• Estimate Fuel Costs and Demand
Elasticities
• Estimate CO2 Emission Rates
• Estimate Energy Efficiency
Improvements and Other Parameters
• Run IEA Energy/CO2 Model
Project Atmospheric CO? Levels
Run ORNL Carbon Cycle Model
Select Representative Time
Series of Atmospheric
Retention Ratios
Project Atmospheric Temperature
• Estimate CO2 - Temperature Sensitivity
• Estimate Thermal Diffusivity
• Project Concentrations of Other
Greenhouse Gases
• Run GISS Temperature Model
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3-3
confidence placed in our findings depends on the reasonableness
of these assumptions and values. The sensitivities of model
outputs to the most important assumptions are described in
Chapter 4.
A general discussion of energy supplies and technologies is
presented in Appendix A. It serves as background to the more
specific treatment of energy supply modeling used in this chapter.
PROJECTING ENERGY USE AND CO? EMISSIONS
The Institute for Energy Analysis (IEA) energy and CC>2 emis-
sion model (Edmonds and Reilly, 1983a) served as the basic vehicle
for developing alternative energy and CC>2 emission scenarios.*
The IEA model is attractive for this type of application for
several reasons. First, it is global in scope and thus encom-
passes world energy markets and international trading in all
principal fuels. Second, it is designed as a sketch model —
that is, as a representation of general structural relationships
between fuel supplies and energy demands. This is highly desir-
able for a study of long-term energy supply and demand. Finally,
the IEA model has been structured to facilitate the evaluation
of energy policy options.
* See Appendix B for a more detailed description of the IEA model,
-------
3-4
Based on a series of sensitivity analyses conducted by both
Edmonds and Reilly, and us, the model also appears to be highly
robust. That is, it is not overly sensitive to any single para-
meter or assumption. This is due, at least in part, to the
use of logit share equations and the resulting continuity of
change in market fuel shares. In other words, the market
responses to major changes in prices, supplies, and demand are
modulated and lagged.
The IEA model divides the world into nine geopolitical
regions (Figure 3-2). Population, economic growth, energy supply
and demand, and all other key variables are specified for each
of these regions. The model estimates prices for each fuel in
each region sufficient to balance supply and demand at each
future point in time (currently, 1975-2100 in 25-year intervals).
Interregional trading in all fuels except electricity (for which
no world market exists) is simulated as part of the market price
solution process. The total quantity of CC>2 emitted is calculated
from the worldwide consumption of the various fuels and the CO2
emissions coefficients of each fuel. Figure 3-3 depicts the key
inputs and outputs and the major computational pathways in the
IEA model.
Although the basic structure of the IEA model was not modi-
fied for this study, many of the parameter values and assumptions
were altered to specify new baseline energy and policy scenarios.
To emphasize these changes, we will refer to our runs as IEA/
EPA scenarios.
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3-5
FIGURE 3-2
GEOPOLITICAL REGIONS IN THE IEA MODEL
Key:
1. U.S.A.
2. OECD WEST (Canada and Western Europe)
3. JANZ (Japan, Australia and New Zealand)
4. EUSSH (Eastern Europe and USSR)
5. ACENP (Asian Centrally Planned)
6. WIDEST (Middle East)
7. APR (Africa)
8. LA (Latin America)
9. SEASIA (South and East Asia)
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3-6
FIGURE 3-3
STRUCTURE OF THE IEA MODEL
r
_L
REGIONAL
POPULATIONS
REGIONAL
LABOR
FORCES
REGIONAL
GNP
REGIONAL
LABOR
PRODUC-
TIVITIES
TECHNO-
LOGICAL
CHANGE
REGIONAL
TAXES AND
TARIFFS
REGIONAL
RESOURCE
CON-
STRAINTS
REGIONAL
BACKSTOP
TECHNOLOGY
DESCRIPTION
REGIONAL
ENERGY
DEMANDS
REGIONAL
PRICES
WORLD
PRICES
REGIONAL
ENERGY
SUPPLIES
GLOBAL
SUPPLIES
AND
DEMANDS
CO2
EMISSIONS
L.
-------
3-7
ENERGY DEMAND PARAMETERS
As shown in Figure 3-3, the major determinants of energy
demand in each region are (1) population and labor force, (2)
labor productivity, and (3) enhanced energy efficiency, on the
positive side, and energy prices on the negative side. These
determinants work together within the economy of each region
to create the underlying demand for fuel liquids, gases, solids,
and electricity.
Values for regional populations and gross national products
(the product of labor forces and labor productivities) used in
the IEA/EPA Mid-range Baseline scenario (see Chapter 4) are shown
in Table 3-1. The values for 1975-2050 are based on a detailed
study of each region and are taken without change from Edmonds
and Reilly (1983b).* Values beyond 2050 extend the 1975-2050
trends, with worldwide population reaching a zero growth level
by 2075. In terms of growth rates, worldwide population averages
1.0 percent per year between 1975 and 2050, and worldwide GNP
averages 2.7 percent per year between 1975 and 2100.
* The Edmonds and Reilly study combined an exhaustive review
of the energy demand literature with specially commissioned
investigations of population growth and productivity change
in each of the nine regions. See Appendix B for additional
documentation.
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3-8
TABLE 3-1
BASELINE VALUES FOR POPULATION, GNP, AND TECHNOLOGICAL CHANGE
£/
Population (billions) GNP (trillions of 1975 $) Enhanced Energy Efficiency
Region
U.S.
Canada & W.
Europe
1975 2000 2025 2050 2075 2100 1975 2000 2025 2050 2075 2100 1975 2000 2025 2050 2075 2100
.21 .25 .28 .29 .29 .29 1.52 2.85 4.59 6.84 10.11 14.661
.41 .48 .53 .55 .56 .56 1.82 3.60 6.42 10.38 16.18 24.65
Japan, Aust., .13 .15 .16 .17 .17 .17 .59 1.59 3.21 5.38 8.41 12.82-
& New Zealand
-1.00 1.28 1.64 2.11 2.70 3.47
E. Europe &
U.S.S.R.
.40 .47 .52 .53 .54 .54 .97 1.76 2.85 4.31 13.85 21.10i
Asian Centrally .91 1.25 1.50 1.61 1.65 1.65 .32 .85 1.75 3.31 13.47 28.20
Planned
.08 .15 .21 .24 .25 .25 .14 .50 1.24 2.49 9.14 14.99
Mideast
Africa .40 .70 .94 1.10 1.15 1.15 .15 .48 1.14 2.14 9.28 18.07
Latin America .31 .54 .72 .82 .85 .85 .32 1.09 2.84 5.16 17.89 29.35
S.& E. Asia 1.13 1.90 2.56 2.89 2.99 2.99 .23 .71 1.65 3.11 11.07 21.03J
-1.00 1.11 1.26 1.44 1.68 1.99
a/ This is an index that reflects improvements in energy efficiency, in addition to those induced by
energy price rises. In the Mid-range Baseline scenario, it applies to only the industrial sector
in the OECD countries, and to the single aggregate sector elsewhere.
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3-9
Accelerated increases in GNP in the current underdeveloped
and developing regions reflect a high population growth rate
earlier in the 21st century combined with higher labor pro-
ductivity later in the century as the economies in these regions
mature.* Viewed from a different perspective, initially high
population growth rates in these regions are brought to zero
through improvements in the standard of living as reflected in
GNP values. This is consistent with the generally held view
that birth rates are negatively correlated with per capita GNP.
With respect to the enhanced energy efficiency index, note
that this parameter reflects improvements in energy efficiency
beyond those induced by increases in energy prices. Our Mid-
range Baseline scenario assumes such improvements occur only
in the industrial sector where the rate of technological innova-
tion historically has been higher than in the other economic
sectors. The average rate of increase over the 125-year period
is 1.0 percent per year in the OECD (first three regions in
Figure 3-2) industrial sectors, and about 0.6 percent per year
in the single aggregate sector elsewhere.
* Average annual rates of increase over the 125-year period
range from about 2.8 percent per year to over 3.0 percent
for the less developed countries.
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3-10
The effect of energy prices on demand is captured in the
set of long-term (25-year) price elasticities of demand for each
region.* For the OECD regions, the sectoral elasticities are:
-0.90 for residential/commercial, -0.80 for industrial, and -0.70
for transportation. (The residential/commercial elasticity
accounts for the increased use of passive and active solar energy
in these sectors.) Since the other regions are not disaggregated
by sectors, a single -0.8 elasticity is employed. Because prices
vary individually for different fuels, interfuel elasticities are
used to reflect the tendency for substitution among fuels. How-
ever, these elasticities vary with the market share of each fuel
and thus over time as the mix of fuels changes in each region.
Total energy demand is driven by GNP both through the con-
sumption of goods and services that require energy for produc-
tion, and through the direct consumption of energy by consumers.
These effects are summarized by income elasticities of demand,
which are set for the OECD countries at 1.0 (with respect to
per capita income) for the residential/commercial and transport
sectors, and 1.0 (with respect to GNP) for the industrial sector.
For the single-sector regions, the aggregate elasticity declines
from 1.25 to 1.0 in Eastern Europe and the USSR, and from 1.4
to 1.0 elsewhere, over the period 1975-2050. Thereafter, it
* A price elasticity of demand is the percent change in demand
caused by a one percent change in the mean price.
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3-11
remains at 1.0 everywhere. The growth in GNP is also affected
by the energy price increases, but the effect is the opposite
of income changes. The GNP-price elasticity is -0.10.
The demand for energy is further disaggregated into fuel
types based on market shares of each fuel in 1975 and assumed
changes in fuel share parameters over time. Market penetration
of alternative fuel types also depends on the relative prices
of these fuels, as reflected in a series of cross-price elas-
ticities. The combination of market share parameters and fuel
price differentials controls the rate at which new energy tech-
nologies emerge and old ones are supplanted. Thus, as noted
previously, sudden changes over any one 25-year period are
avoided.
ENERGY SUPPLY PARAMETERS
Three generic energy supply categories are defined based
on the physical availability of the resource:
Resource- Resource- Unconstrained
Constrained Constrained Sources
Conventional Renewable
Sources Sources
Conventional Hydro Unconventional Oil
Oil Biomass Unconventional Gas
Conventional (Solids and Coal (Solids and
Gas : Synthetic Synthetic Fuels)
Fuels) Solar Nuclear
Definitions of each fuel type can be found in Appendix A.
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3-12
The rates of production of conventional oil and gas are
represented by simple resource depletion curves. This assumes
that the rates of oil and gas extraction over the next few decades
follow historical trends and are insensitive to changes in market
prices. Although this assumption is not literally valid and
leads to some distortion in estimated oil and gas prices, the
inaccuracies are mitigated since conventional oil and gas will
have become relatively minor sources of energy by the middle of
the next century — well within our time frame.
Hydropower for generating electricity is modeled in a fashion
similar to unconventional oil and gas, with one exception. Rather
than resource depletion, maximum resource utilization is simulated.
Biomass is both resource-limited and price-sensitive. That is,
maximum land areas for growing fuel crops have been estimated
for each region, and these limits bound a land area-energy price
supply curve. Upper limits on the amount of waste available for
use as fuel are estimated as a function of GNP in each region.
All other fuels are assumed to be present in large enough
quantities as to be inexhaustible within the time horizon of
this study.* Production of these fuels is thus influenced only
by their market price. However, a distinction is made between
* For nuclear power, the development and use of breeder reactors
is assumed. See Appendix A for further elaboration.
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3-13
unconventional oil (primarily shale oil),* unconventional (deep)
gasf and coal, on the one hand, and nuclear and solar on the
other. The first group is assumed to follow both a long-run
"normal" rate of growth (which occurs at constant real prices)
and a shorter (25-year) supply schedule that adjusts the produc-
tion level above or below the "normal" level corresponding to
higher or lower than "normal" prices.
Both nuclear and solar-electric** power are considered true
"backstop" fuels. That is, their costs of production remain
constant (or decrease) for all time scales. Moreover, the demand
for these fuels is derived from the total demand for electricity,
and the costs of producing electricity from nuclear and solar
power relative to competing fuels.
The demand for and market price of liquids and gases similarly
influences the production of synthetic fuels from coal and biomass,
although synfuels are modeled by a logit-share function, rather
than by superimposition of long- and short-run supply schedules
as above.
* Unconventional oil includes both heavy oil and tar sands/shale
oil (see Appendix A). However, although the IEA/EPA model
runs include all types of unconventional oil in their resource
estimates, production costs are based on shale oil costs.
** Solar for nonelectric uses is included in the IEA conservation
category.
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3-14
A key production parameter for all emerging energy sources
is the minimum production cost, or breakthrough price. This is
the lowest market price at which any production is feasible.*
Breakthrough prices are shown in Table 3-2 for each emerging
energy source in the IEA/EPA Mid-range Baseline scenario. Note
that the price for each source, other than unconventional gas,
declines over time (a smooth nonlinear curve connects 1975 and
2100), reflecting technological advances in extraction and pro-
cessing technologies. Since unconventional gas is currently
being produced in several parts of the world (and is thus not
actually an "emerging" source), the associated technology can
be considered mature and subject to a modest increase in real
costs over time.
For purposes of comparison, breakthrough prices for the
other principal fuel types are shown in Table 3-3. These cost
estimates include pollution control and other nonenergy costs.
They are based on the results of an energy technology comparison
as reported in Reilly and associates (1981), with extrapolations
to 2100 and with modifications based on more recent cost data.
* For synfuels, the "breakthrough price" concept is not directly
applicable. Production costs relative to market prices for
liquids and gases are used to determine the relative amounts
of liquid, gaseous, and solid fuels made from coal and biomass.
A small amount of synfuel production may occur even when market
prices are slightly below production costs.
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3-15
TABLE 3-2
BREAKTHROUGH PRICES FOR EMERGING ENERGY SOURCES IN THE MID-RANGE
BASELINE SCENARIO
Fuel"
a/
Breakthrough Price (1980 $)
Beginning (1975) Final (2100) Production Initiated
Unconventional Oil
(primarily shale)
Unconventional Gas
c/
Synthetic Oil
c/
Synthetic Gas"
Centralized Solar-
Electric
12.0 - 17.8 ($/GJ)
70 - 103 ($/boe)
5.2 ($/GJ)
0.005 ($/cf)
100 ($/GJ)
580 ($/boe)
100 ($/GJ)
0.10 ($/cf)
153-570" ($/GJ)
2.32 - 8.63 ($/kWh)
7.1 ($/GJ)
41 ($/boe)
6.4 ($/GJ)
0.006 ($/cf)
6.7
39
($/GJ)
($/boe)
5.0 ($/GJ)
0.005 ($/cf)
b/
9-22 ($/GJ)
0.29-0.33 ($/kWh)
8.8 ($/GJ)
51 ($/boe)
5.5 ($/GJ)
0.006 ($/cf)
7 ($/GJ)
41 ($/boe)
5.5 ($/GJ)
0.006 ($/cf)
20 ($/GJ)
0.30 ($/kWh)
a/ See Appendix A for definitions.
b/ Varies by region.
£/ Synthetic fuels are not, strictly speaking, modeled with breakthrough prices.
Rather, the production costs are used together with other factors to estimate
the fractions of raw material (coal and biomass) that are used to produce
solid, liquid, and gaseous fuels. In addition, the costs of producing syn-
fuels are higher for biomass than for coal.
-------
3-16
TABLE 3-3
BREAKTHROUGH PRICES FOR TRADITIONAL ENERGY SOURCES
IN THE MID-RANGE BASELINE SCENARIO
Fuel Breakthrough Price (1980 $)
Beginning (1975) Final (2100)
Coal 0.37 ($/GJ) 0.49 ($/GJ)
11 ($/mtce) 15 ($/mtce)
Biomass 0.57 ($/GJ) 0.57 ($/GJ)
17 ($/mtce) 17 ($/mtce)
Nuclear 9.6 - 36.4 ($/GJ) 10.0 ($/GJ)
0.15 - 0.55 ($/kWh) 0.15 ($/kWh)
f/ Varies by region.
-------
3-17
For two fuel sources (unconventional gas and coal) modeled
by superimposing long-run and medium-run supply schedules, the
reference price of the "normal" production level also increases
over time. In other words, the long-run supply schedules slope
upward. The time-rate of increase in reference price equals the
rate of increase in breakthrough price. In a similar but opposite
sense, the long-run "normal" supply curve for unconventional oil
slopes downward, paralleling the decline in breakthrough price.
All IEA/EPA scenarios assume that significant commercializa-
tion of exotic energy sources will not be realized within the
next 120 years. Thus, rapid development of fusion technology
or new methods of generating hydrogen during the first half of
the next century, for example, could make model projections of
fossil fuel use unreliable by the end of the next century, even
if all other assumptions were to hold. (See Appendix A for a
discussion of exotic sources.)
BALANCING SUPPLY AND DEMAND
Once supply and demand schedules have been estimated for each
fuel type in each region, the model solves for market-clearing
prices in each region. Starting points are the world prices for
each fuel traded internationally, plus transport costs and tariffs,
if any. Regional prices are then adjusted for each fuel (gases,
liquids, solids, and electricity) until supplies and demands match
within a predesignated increment.
-------
3-18
ESTIMATING CO? EMISSIONS
The total quantity of CC>2 emitted is calculated as the pro-
duct of fuel used in each time period and CC>2 emitted per unit
quantity of each fuel. The following CC>2 (carbon) emission
coefficients are employed (Edmonds and Reilly, 1983b):
CO? Emissions (Terragrams of Carbon/EJ)
Fuel Preparation Combustion Total
Conventional Oil — 19.7 19.7
Unconventional Oil 27.9 19.7 47.6
(Shale Oil)
Gas — 13.8 • 13.8
Coal — 23.9 23.9
Synthetic Oil 18.9 19.7 38.6
(f rom coa1)
Synthetic Gas 26.9 13.8 40.7
(from coal)
All other fuels are assumed to contribute no CO2 to the atmosphere.
In the case of synthetic fuels from biomass, this implies that
biomass is used to generate the energy needed for liquifaction
and gasification.
Using these coefficients, estimates of global CO2 emissions
are generated for each 25-year period. Estimates at 5-year inter-
vals are then prepared for the next analytical step by interpola-
tion using a curve-fitting procedure. The starting date for
estimating atmospheric CO2 is 1980.
-------
3-19
PROJECTING ATMOSPHERIC CO? LEVELS
A global carbon cycle model developed at Oak Ridge National
Laboratory (ORNL) (Emmanuel, et al., 1981) was employed to esti-
mate the fate of CC>2 emitted into the atmosphere and, ultimately,
the airborne fraction (retention ratio).* The ORNL model simu-
lates stocks of carbon in three major compartments: the atmosphere,
the ocean (surface and deep layers), and the biosphere (ground
vegetation, trees, and soil). Changes in the quantities of carbon
in these reservoirs are affected primarily by (1) CO2 emissions,
(2) land clearing and reforestation, and (3) temperature changes.
The last factor implies a major feedback loop, since increasing
atmospheric CO2 levels will raise atmospheric and ocean tempera-
tures which, in turn, will increase the flow of carbon from the
ocean to the atmosphere. Moreover, the flows of carbon among
other compartments are also affected by temperature.
Since temperature is a key variable in estimating the fate
of emitted CO2, a special effort was made to represent the tempe-
rature effects of rising CO2 in the atmosphere as realistically
as possible. This involved coupling the ORNL and Goddard
Institute for Space Studies (GISS) models, since CO2~temperature
relationships are represented in a more sophisticated (and pre-
sumably more accurate) fashion in the GISS model than in the
ORNL model. Details of the coupling procedures are described
in Appendix E.
* See Appendix C for a more detailed description of the ORNL model,
-------
3-20
To simplify the analysis, we assumed no net change in forest
cover over the 120-year period of interest. This is not unrea-
sonable, given the offsetting trends in land clearing and refore-
station currently observed in different parts of the world.
Using the coupled ORNL-GISS models we made several runs for
a variety of energy use/C02 emission scenarios. These generated
a large set of 10-year average retention ratios, from which we
selected four representative series. These correspond to very
low, low, medium, and high CC>2 emission scenarios, as indicated
in Figure 3-4. High rates of growth in CC>2 emissions imply a
gradual saturation of natural carbon sinks and thus an increase
in atmospheric retention of CC>2 over time, while low emission
rates suggest a constant or even slightly falling retention ratio.
Note also that the retention ratios calculated by the ORNL
model are somewhat higher than those estimated from empirical data
on historical fuel use, land use changes, and measured increases
in CC>2 concentrations. However, substantial uncertainty1 accom-
panies the interpretation of past empirical estimates, and higher
future retention ratios are consistent with current scientific
understanding of the carbon cycle (see Chapter 2).
The CC>2 emission categories in Figure 3-4 cover a wide range
of scenarios. The designation of only four separate categories
may appear to introduce substantial error, since the retention
ratios assigned to these categories differ considerably, especially
in the later years. In addition, the rates of growth in emissions
-------
FIGURE 3-4
FINAL ATMOSPHERIC CO2 RETENTION RATIOS FOR FOUR TYPES OF
C02 EMISSION SCENARIOS
(ADDITIONAL TONS OF ATMOSPHERIC CO2/TONS OF CO2 EMITTED)
.sor
.70
.60
.50
I
OJ
I
to
I
I
1980 1990 2000 2010 2020 2030 2040 2050 2060 2070 2080 2090 2100
DEFINITIONS: VERY LOW SCENARIO = DECLINING ANNUAL EMISSIONS
LOW SCENARIO = 1.0 - 1.49% ANNUAL GROWTH IN EMISSIONS
MEDIUM SCENARIO = 1.5 - 1.79% ANNUAL GROWTH IN EMISSIONS
HIGH SCENARIO = GREATER THAN 1.79% ANNUAL GROWTH IN EMISSIONS
NOTE: NO SCENARIOS WERE INVESTIGATED WITH GROWTH RATES BETWEEN ZERO AND 1.0% PER YEAR.
-------
3-22
used in defining the emission scenarios in Figure 3-4 are average
annual rates over the 120-year time span of this study. These
average rates obviously mask significant trends in annual rates
within this time span, which may imply changes in retention ratios.
However, the end product of these investigations — changes in
atmospheric temperature — is much less sensitive to variations
in retention ratio than is atmospheric CO2» A comparison of (1)
estimated temperature levels derived from atmospheric CC>2 concen-
trations computed by the ORNL model with (2) temperature levels
associated with CC>2 concentrations calculated from the represen-
tative retention ratios revealed no significant differences.
Using representative series of retention ratios derived from
the ORNL models output accomplishes two goals. First, it incor-
porates, in an approximate fashion, the flows of carbon and changes
in carbon reservoirs in the global carbon cycle as estimated by
the ORNL model. Second, it avoids the necessity of running the
costly ORNL model for each new scenario. Instead, the appropriate
retention ratio series is selected and atmospheric levels of C02
computed directly by the GISS model.
PROJECTING ATMOSPHERIC TEMPERATURE LEVELS
Once atmospheric levels of CO2 have been estimated for
future time periods, these levels are translated into changes in
atmospheric temperature using a simplified heat flux model of
the earth-atmosphere system. This is the GISS model — a simpli-
-------
3-23
fication of a one-dimensional radiative/convective (RC) atmospheric
temperature model developed at GISS (Hansen, et al., 1981; and
Lacis, et al., 1981).*
In essence, the GISS model computes changes in the flux of
heat from atmosphere to land and ocean, which results from CC^'s
capacity to absorb infrared radiation from the earth. As dis-
cussed in Chapter 2, some of this energy is reradiated toward
the earth's surface, thus raising the temperature of the earth
and the atmosphere at the surface and rebalancing total energy
received and emitted by the earth-atmosphere system. The rate
at which this occurs for a given rise in C02 depends on the
degree to which the additional heat is dissipated in the ocean
and on several feedback mechanisms, the most important of which
is the increase in water vapor with rising temperature.
The GISS model represents both the heat flux from the atmos-
phere to the surface (well-mixed) layer of the ocean, and from
this layer into 63 lower layers (the thermocline) of the ocean.
A simple "box diffusion" scheme is employed to represent the
diffusion and transport of heat in the ocean. Since this process
is a relatively slow, several years may be required for the
earth-atmosphere system to reach thermal equilibrium for a given
* See Appendix D for a more detailed description of the GISS
model.
-------
3-24
increase in CC>2.* Thus, atmospheric temperature rises always
lag CO2 rises. For large rates of growth in annual CC>2 emissions,
this time lag may be as much as a few decades.
The effects of rising temperature on atmospheric water vapor
and on cloud cover and height are treated explicity in the GISS
model. These feedback mechanisms also delay the attainment of
thermal equilibrium, although the timing effect is short compared
with that of heat dissipation in the ocean.
The GISS model incorporates various factors that influence
atmospheric temperature, in addition to CO2- These include the
level of other greenhouse gases (specifically, nitrous oxide,
methane, and chlorofluorocarbons), the change in atmospheric
optical depth** due to volcanic activity, and variations in solar
luminosity. Values for those parameters are based on extrapola-
tions of past trends or on average measured levels. However,
since data on historical trends and current levels for these
parameters are sketchy at best, the assignment of future values
must be considered highly speculative. The temperature sensitivity
(the net change in temperature at equilibrium from a doubling of
pre-industrial CC>2) and the rate of heat diffusion in the ocean
are the final two key parameters.
* Of course, the atmosphere never attains equilibrium if
the concentrations of greenhouse gases change continually.
** Optical depth is a dimensionless parameter that measures
the opacity of the atmosphere.
-------
3-25
Values assigned to all parameters are shown in Table 3-4.
References and brief explanations for these values are also in-
cluded in Table 3-4 and are described in more detail in Appendix D.
Since most of the effects of CC>2 will be manifest in terms
both of rises in atmospheric temperature and of the consequences
of these rises, much of the discussion in Chapter 4 will focus on
temperature trends. It is useful to keep in mind, however, that
tracing changes in fuel use through to the impact on atmospheric
temperature requires many assumptions about behavioral responses
to changing technologies and costs, energy use, and production,
and about physical and biological relationships involving CC>2.
-------
3-26
TABLE 3-4
PARAMETER VALUES FOR THE GISS MODEL
Parameter
Atmospheric Level of €({4
Atmospheric Level of
Atmospheric Level of CC12F2
Atmospheric Level of CC13F
Volcanic Activity
Change in Solar Luminosity
Temperature Sensitivity
Value
• Constant 1.6 ppm for all
years
• 1.6 ppm through 1980,
increased by 2.0% per year
thereafter
• Constant 0.300 ppm for all
years
• 0.300 ppm through 1980,
increased by 0.2% per year
thereafter
• Constant 0.306 ppb for a/
all years starting in 1980
• 0.306 ppb in 1980, increased
in 10-year decreasing incre-
ments to 1.50 ppb in 2100
• Constant 0.176 ppb for a/
all years starting in 1980
• 0.176 ppb in 1980, increased
in decreasing 10-year incre-
ments to 0.642 ppb in 2100
• Constant level of activity:
increase in optical depth
of a constant 0.007 every
year from 1980-2100
• Zero
1.5°C
3.0°C
4.5°C
Comments
Estimates of growth for
1970-80 range from 0.5
to 3.0% per year.
Estimates of growth for
1975-80 range from 0.1
to 0.5% per year.
Growth estimates are
based on measured levels
between 1970 and 1980, and
assume a decrease in
emissions over the 120
year time period
This is the average
measured value over
the last 100 years
No net change is
projected for the
next 120 years
Spans the estimated
50% confidence
interval for Te
Reference
Lacis, et al.,
1981
Rasmussen and
Khalil, 1981
Lacis, et al.,
1981
Weiss, 1981
Lacis, et al.,
1981.
Lamb, 1970
Hansen, et al.,
1981
Hoyt, 1979
Hansen, et al.,
1981
Charney, 1979
Diffusivity
1.18 cm2/sec
Abbreviations:
CH4 = methane, N2O = nitrous oxide, CC12F2
and CC13F = chlorofluorocarbons, ppm = parts
per million, ppb = parts per billion
This is within the
accepted range of
diffusivity values
for a "box diffusion"
model and consistent
with a 3.0"C temperature
sensitivity value in the
GISS model
Broecker et al,
1980
Hansen, et al. ,
1981
a/ Emissions of chlorofluorocarbons were initiated in the 1940s but did not accumulate to significant atmospheric
~ levels until the 1960s and 70s. Assuming zero levels before 1980 does not distort estimates of atmospheric
temperature appreciably.
-------
CHAPTER 4
THE EFFECTIVENESS OF ENERGY POLICIES FOR CONTROLLING CO?
To explore the possible effects of future energy scenarios
on atmospheric CC>2 and temperature, a large number of analyses
were undertaken using the models described in Chapter 3. Each
separate run focused on one or more key assumptions or examined
the effect of specific policies designed to slow the rate of CC>2
rise. The results of these analyses are described and interpreted
in this chapter.
For clarity in discussing the results, the energy scenarios
are divided into two groups — baseline projections and policy
assessments. The baseline projections depict alternative future
patterns of energy use and resulting atmospheric CC>2/temperature
levels in the absence of any overt public effort to lower CC>2
emissions. These IEA/EPA projections include a reference base-
line (Mid-range), four lower CC>2 baselines (High Renewable, High
Nuclear, High Electric, and Low Demand), and one higher CC>2 base-
line (High Fossil). Policy assessments do just the opposite —
they evaluate the effectiveness of policies intended to slow or
limit the rate of CC>2 rise and atmospheric warming as measured
in terms of differences from the reference (Mid-range) baseline
projection. Policy options investigated include taxes on CC>2
emissions and various bans on specific types of fossil fuels.
-------
4-2
Although the distinction between baseline projections and policy
assessments is sometimes arbitrary (e.g., a low cost renewable
energy baseline could be the result of government subsidies for
renewable energy use), using a range of energy scenarios indepen-
dent of any policy considerations is useful in clarifying the
uncertainty involved in projecting future energy use, and thus
in providing a context for judging the effectiveness of policies.
BASELINE SCENARIOS
The starting point in developing baseline scenarios is a
projection of future fuel use patterns which represents a com-
posite of "best guesses" about the state of the world through
the next century. This case is named the Mid-range Baseline
scenario. Predicting the future is not the goal here. Rather,
the Mid-range Baseline serves simply as a reference point for
asking "what if" questions. The answers to these questions shed
light on, first, the overall degree of uncertainty in estimating
atmospheric effects produced by future fuel-use patterns, and
second, the relative importance of specific assumptions concerning
energy behavior and atmospheric responses.
MID-RANGE BASELINE
Energy Supply and Demand
Assumptions regarding growth in population and labor produc-
tivity, technological change (enhanced energy efficiency), energy
use behavior, and fuel production costs used to specify the
-------
4-3
Mid-Range Baseline scenario were listed in Chapter 3. Figure
4-1 charts the estimated change in several fuel use characteris-
tics from 1975 to 2100. Point estimates at 25-year intervals
are shown, with straight lines connecting the points for display
purposes.
Note first the relatively modest rise in final* energy use
through 2050 (about 1.2 percent per year for final energy use)
and the steep rise thereafter (about 2.1 percent per year).
This is due to the substantial increase in GNP after 2050 in all
currently underdeveloped and developing regions (see Table 3-1).
Lower GNP growth rates in the less developed and developing regions
were used to test the sensitivity of energy-use estimates to GNP
growth. By lowering the average annual rate of GNP growth (2050-
2100) in all less developed and developing regions from about
3.8 percent to 2.8 percent, final energy use in 2100 dropped by
17 percent to roughly 1100 EJ.
The energy use curves also reflect a large amount of energy
conservation, that is, energy saved through solar applications
in the residential and commercial sectors plus reduced demand
due to increases in the price of energy. In fact, the estimated
amount of final energy conserved is so large that it exceeds
the amount used after 2050. This conservation is also reflected
* Final energy use refers to the energy value of the fuels actually
used. That is, energy lost in fuel preparation is not included.
Total energy use is referred to as "primary energy".
-------
4-4
FIGURE 4-1
MID-RANGE BASELINE SCENARIO: ENERGY USE CHARACTERISTICS S/
ENERGY USE
LIQUIDS PRODUCTION
CONVENTIONAL
— — UNCONVENTIONAL OIL
SYNTHETIC OIL
300
200
100
GAS PRODUCTION
CONVENTIONAL OIL
— — UNCONVENTIONAL GAS
SYNTHETIC GAS
1975 2000 2025 2050 2075 2100
SOLIDS PRODUCTION
1975 2000 2025 2050 2075 2100
ELECTRICITY PRODUCTION
1975 2000 2025 2050 2075 2100
AVERAGE REGIONAL PRICES
COAL (TOTAL)
— — BIOMASS (SOLID FUEL
ONLY)
TOTAL
COAL
NUCLEAR
SOLAR
1975 2000 2025 2050 2075 2100
T 1 ii
1975 2000 2025 2050 2075 2100
LIQUIDS
— —GAS
SOLIDS
ELECTRICITY
1975 2000 2025 2050 2075 2100
PRODUCTION OF ELECTRICITY, UNCONVENTIONAL FUEL, AND SYNTHETIC FUEL IS SPECIFIED IN UNITS OF FINAL ENERGY.
PRODUCTION OF OTHER FUELS IS IN UNITS OF PRIMARY ENERGY.
-------
4-5
in declining energy/GNP ratios from about 43 GJ/$ in 1973 to
about 16 GJ/$ in 2100, a decline of over 60 percent. Thus, the
energy effects of increasing GNP are offset to some extent by
efficiency improvements.
These energy-use estimates can be placed in perspective by
comparing them with estimates made by other investigators. The
International Institute for Applied Systems Analysis has projected
primary energy use worldwide of between 705 and 1,123 EJ in 2030
(Anderer, et al., 1981). A much lower energy-use future is
envisioned by Lovins—165 EJ in 2030 (Lovins, et al., 1981).
Our projection of about 710 EJ in 2025 thus falls in the middle
of this range of projections.
The fuel production charts in Figure 4-1 reveal that increasing
energy demand is satisfied largely by coal, and after 2025, by both
unconventional and synthetic sources of oil and gas. Use of elec-
tricity also increases sharply after 2050. Conventional sources
of oil decline rapidly after 2000 while conventional sources of
gas peak in 2025 with a steady decline thereafter. Interestingly,
synthetic gas is estimated to be much more price-competitive than
unconventional gas throughout the next century, while synthetic
oil is first more (before 2075) and then less competitive than
unconvention oil (largely shale oil). The crossover in production
curves for synthetic versus unconventional oil reflects the fact
that, despite technological improvements, synfuel costs are tied
to the steadily increasing cost of raw materials (almost exclusively
-------
4-6
coal), while costs for unconventional oil reflect only the de-
creases from maturation of the technology. Coal shows unfaltering
strength throughout the entire period both as a solid fuel and
as the raw material for synthetic oils and gases. Biomass and
solar electric remain minor fuel types. Biomass is undercut
economically by coal, and solar is underpriced by both nuclear
and coal.
Fuel-price patterns reveal differences in both production
costs and demands among fuel types.* Higher prices for elec-
tricity and liquids are sustained by the fact that, for some end
uses, no other fuel can substitute. For example, some industries
such as aluminum smelting are heavily invested in electrolytic
technologies, and transportation vehicles continue to be operated
by liquid fuels due to the high energy content per unit weight
and transportability of liquids. The rising prices of all fuels
over time reflect the depletion of less costly sources relative
to demand. Since, of all the unconstrained fuels, coal remains
plentiful and is characterized by the initially lowest and least
rapidly rising long-term cost function, its rate of price increase
is the smallest.
* The fuel prices shown in Figure 4-1 are average regional prices
unweighted by fuel use.
-------
4-7
CO? and Atmospheric Responses
The changing pattern of fuel use estimated for the IEA/EPA
Mid-range Baseline scenario will produce a specific trend in CO2
emissions over time. These emissions in turn will raise the level
of atmospheric CC>2 and temperature, the extent of the estimated
increase being dependent on assumptions about how the earth-
atmosphere system responds to additional CC>2 emissions.
Figure 4-2 shows the time course of CC>2 emissions, CC>2 con-
centrations, and atmospheric temperature at the surface of the
earth for the Mid-range Baseline scenario from 1980-2100. Atmos-
pheric CC>2 and temperature values were estimated using the
following GISS model parameters: greenhouse gases other than CC>2
were assumed to increase moderately over time, the equilibrium
temperature for a doubling of CC>2 (Te) was set at 3.0°C, and
the other parameters were set at their nominal values (those
identified in Table 3-4).
All three model outputs increase steadily in Figure 4-2
through 2040, with CC>2 concentrations doubling from pre-indus-
trial levels around 2060.
-------
4-8
FIGURE 4-2
CO2 MODELING RESULTS FOR THE MID-RANGE BASELINE SCENARIOS
50
40
30
20
10
CO 2 EMISSIONS
1980 1990 2000 2010 2020 2030 2040 2050 2060 2070 2080 2090 2100
u
E
UJ
X
w 2
I
Ul
oc
700
600
500
400
300
200
100
ATMOSPHERIC EFFECTS
CO2 LEVEL
TEMPERATURE
1980 1990 2000 2020 2010 2030 2040 2050 2060 2070 2080 2090 2100
5.0
4.0
H
rn
_~ mm
3.0 3J _
> z
9 3
2'° si
O X
O m
in 3D
-------
4-9
After this date, the rate of increase in CC-2 emissions accelerates
dramatically. This is due largely to (1) the assumed maturation
of the world's economies after 2050 and the resulting increase
in GNPs, and (2) the accelerated use of synthetic fuels after
2025 and unconventional oil (especially shale oil) after 2050.
These factors combine to produce an average annual rate of increase
in CC>2 emissions of about 2.4 percent from 2050-2100. (However,
this is still lower than the rate of increase from 1950-1980,
roughly 4.1 percent per year [Clark, 1982]).
To further illustrate patterns and time trends in projected
CO2 emissions, the IEA model estimates for each of the nine regions
and for three time periods are shown in Figure 4-3. In 2000, CC>2
emissions are dominated by the developed regions (Regions 1-4 in
Figure 4-3). Together they account for almost 73 percent of
global emissions. However, the growing importance of the other
5 regions is readily apparent. By 2100, the proportion of global
CC>2 emissions accounted for by the three developed regions has
fallen to just under 55 percent. This fraction would be even
lower except for the large quantities of coal and shale oil
located in the developed regions (especially the U.S., Canada,
Europe, and the U.S.S.R.) and the resulting large quantities of
CC>2 generated in producing usable fuels from these resources.
To demonstrate the sensitivity of the atmospheric tempera-
ture results to the primary GISS modeling parameters, the Mid-
range Baseline scenario was modeled for three values of Te
-------
FIGURE 4-3
GEOGRAPHIC DISTRIBUTION OF CO2 EMISSIONS FOR THE
MID-RANGE BASELINE SCENARIO
10.0 i
9.0
cc 8.0
7.0
5 6-°
5.0
4.0
3.0
2.0
1.0
REGION 1-USA
2-CANADA& W. EUROPE
3-JAPAN, AUSTRALIA,
N. ZEALAND
4-USSR & E. EUROPE
5-CENTRALLY
PLANNED ASIA
6-MIDDLE EAST
7-AFRICA
8-LATIN AMERICA
9-S.E. ASIA
i
H"
O
123456789
123456789
1 234567 89
2000
2060
2100
-------
4-11
(1.5°Cf 3.0°C, and 4.5°C), both with and without growth in atmos-
pheric levels of other greenhous gases. This range in Te encom-
passes the NAS confidence interval (3.0 +_ 1.5°C), while the range
in growth rates of other greenhouse gases, from 0 (i.e., constant
levels of trace gases) to those extrapolated from historical rates
(see Table 3-4), may or may not be a good approximation of the
variability in future levels of trace gases. A uniformly higher
growth rate for all trace gases (2.0 percent per year) was also
used together with the highest value of Te (4.5°C) to establish
an upper bound for the rate of temperature increase. The results
are snown in E'igure 4-4.
Uncertainty in the Te and trace gas parameters produces
substantial variability in the rate of temperature increase.
Measured in terms of the year in which a temperature rise of
2°C is experienced, the overall variability is about 80 years
(from roughly 2015 to 2095 for the extreme cases). Looking just
at the curves for a moderate growth rate in greenhouse gas levels
(middle curves in Figure 4-4), varying the assumed temperature
sensitivity of the atmosphere (temperature equilibrium) between
Te = 4.5°C and 1.5°C is seen to change the estimated 2°C year
from 2030 to 2070. Likewise, assuming that other greenhouse gases
remain at their current levels (and that Te = 1.5°C) delays the
2°C date roughly 25 years, from about 2070 to 2095. On the other
hand, assuming a very high growth rate of greenhouse gases other
than C02 (and that Te = 4.5°C) advances the 2°C date by another
15 years, from 2030 to 2015.
-------
FIGURE 4-4
SENSITIVITY OF MID-RANGE BASELINE TEMPERATURE ESTIMATES
0°
Te: TEMPERATURE EQUILIBRIUM
OQG: OTHER GREENHOUSE
1980 1990 2000 2010 2020 2030 2040 2050 2060 2070 2080 2090 2100
-------
4-13
Figure 4-4 reveals considerable nonlinearity in the way
uncertaintities in temperature sensitivity and the rate of growth
of other greenhouse gases combine to change the estimated date
of a 2°C rise in temperature. This is due in part to the angle
with which the 2°C line intersects the curves. Moreover, the
realism of the range in parameter values remains in doubt, at
least for the greenhouse gas growth rates. Nevertheless, this
type of sensitivity analysis provides a means for gauging the
relative importance of these two parameters. Based on the curves
in Figure 4-4, uncertainty in temperature sensitivity appears
to introduce about 35-40 years of variability in the estimate of
when a 2°C temperature rise will be observed, while uncertainty
in the growth of other greenhouse gases introduces roughly 40-45
years of variability.
The size of these changes in the rate of temperature increase
appear to be highly significant in the context of time needed by
public and private decisionmakers to develop and implement response
strategies. Although a simple set of "more likely" assumptions
(Te = 3.0°C and moderately increasing levels of other greenhouse
gases) is employed for investigating baseline and policy scenarios,
the uncertainty which accompanies these assumptions must be kept
in mind when interpreting the significance of the analytical
results.
-------
4-14
OTHER BASELINE SCENARIOS
As the name implies, the Mid-range Baseline scenario is
believed to be representative of likely future conditions. How-
ever, other scenarios may be equally probable given the incomplete
nature of the data base on which these projections are based and
the inherent risks in projecting events in the distant future.
To gauge the variability in atmospheric responses from changes
in baseline energy conditions, several alternative baseline
scenarios were investigated.
Energy Supply and Demand
The first alternative is a scenario with reduced CC>2 emis-
sions that features (1) lower production costs and therefore
higher use of renewable fuels, and (2) increased use of passive
solar building designs in the residential and commercial sectors
of the OECD regions. This is called the High Renewable scenario.
First, the cost (assumed constant over time) of producing biomass
from wastes and from energy farms is reduced by half at every
step of the supply schedule. Second, the rate of decline in
costs of producing solar-powered electricity is accelerated and
the final costs reduced by between 68 and 77 percent, depending
on the region. Finally, use of passive solar energy is expanded
by increasing the "enhanced energy efficiency" parameter at a 0.2
percent average annual rate.
-------
4-15
Figure 4-5 compares trends in selected fuel-use characteris-
tics between the High Renewable and Mid-range scenarios. First,
energy use is higher. The reduction in solar electric and biomass
production costs lower energy prices, thus stimulating energy
demand. For example, the average regional price of electricity
is one third less by 2100 in the High Renewable scenario. As a
result, electricity production is up "appreciably, as shown,
especially solar-powered production. From a CC>2 emissions per-
spective, however, the positive effect of increased use of solar
electricity is eroded since nuclear rather than coal is primarily
replaced as the generation fuel. (That is, solar replaces nuclear
as the marginal cost fuel. ) As will be shown later, the reduction
in C(>2 emissions compared with the Mid-range Baseline is substan-
tial but not dramatic (about 20 percent reduction between 2050 and
2100). Figure 4-5 also reveals that the use of biomass as a solid
fuel is increased only slightly by the 50 percent reduction in
production costs since coal is still less expensive and can meet
demand for solids in most regions.
A lower CO2~producing baseline which relies increasingly on
nuclear fuel was also investigated. Increased use of nuclear
power is simulated by (1) reducing the final (in 2100) production
costs of nuclear by half (and thus production costs in earlier
years by somewhat less than half), and (2) increasing the para-
meters which control (along with relative cost) the fuel shares
for electrity generation. The latter change implies fewer indirect
-------
4-16
FIGURE 4-5
HIGH RENEWABLE vs MID-RANGE SCENARIOS: FUEL USE CHARACTERISTICS-S/
K.
Ill
Q.
3
K
EC
8!
UJ
1200
1000
800
600
400
200
1975
1400
1200
1000
800
600
400
200
RNAL ENERGY USE
—_ HIGH RENEWABLE
MID-RANGE
2000
2025
2050
2075
2100
SOLIDS PRODUCTION
— HIGH RENEWABLE
MID-RANGE
1975
700
600
500
400
300
200
100
1975
UNCONVENTIONAL OIL PRODUCTION
HIGH RENEWABLE
•MID-RANGE
2000 2025 2050 2075
ELECTRICITY PRODUCTION
HIGH RENEWABLE
MID-RANGE
2000
2025
2050
2075
2100
PRODUCTION OF SOLIDS IS SPECIFIED IN UNITS OF PRIMARY ENERGY. PRODUCTION OF OTHER FUELS IS IN UNITS OF FINAL
ENERGY.
-------
4-17
cost restrictions on the construction of nuclear facilities such
as reductions in the time to obtain construction permits. In
addition, a temporary reduction in generating capacity and a
longer term slow-down in the rate of nuclear power plant con-
struction as a result of a nuclear accident sometime between
2000 and 2025 is superimposed on this baseline. The accident
scenario is intended to simulate the consequences of an intermit-
tent acceleration of nuclear power use. These scenarios are
called High Nuclear and High Nuclear with Accident Baselines.
Figure 4-6 shows the major fuel use features of these scena-
rios. Lowering production costs and easing the restrictions on
nuclear power is a powerful stimulant to the use of electricity.
And as use of electricity expands, given this set of cost assump-
tions, production of coal and unconventional oil declines. How-
ever, as costs decrease, total energy demand grows as well, up
to 20 percent by 2100. The impact on CO2 emissions is a reduction
from the Mid-range Baseline but an increase above the High Renew-
able Baseline. The effect of the simulated nuclear accident is
to cause a temporary reduction in energy demand, but the rate of
growth of nuclear power in the long-run is not affected. The
realism of the High Nuclear with Accident scenario remains in
question since the IEA model does not explicitly consider disrup-
tions to supply factors which likely would occur if a moratorium
on new plants was declared for an extended period of time. The
effect on CC>2 of a moratorium is to bring total emissions closer
to the Mid-range Baseline.
-------
FIGURE 4-6
HIGH NUCLEAR VS. MID-RANGE SCENARIOS: ENERGY USE CHARACTERISTICS £/
EC
EC
UJ
1400
1200
1000
800
600
400
200
FINAL ENERGY USE
MID-RANGE
—— HIGH NUCLEAR
HIGH NUCLEAR WITH
ACCIDENT
1975
2000
2025
2050
700
600
500
400
300
200
100
ELECTRICITY PRODUCTION
MID-RANGE
HIGH NUCLEAR
2075
2100
1975
2000
2025
2050
2075
2100
I
t-»
oo
K
EC
Ul
O.
600
500
400
300
200
100
UNCONVENTIONAL OIL PRODUCTION
MID-RANGE
— HIGH NUCLEAR
HIGH NUCLEAR WITH ACCIDENT
1975
2000
1400
1200
1000
800
600
400
200
COAL PRODUCTION
MID-RANGE
HIGH NUCLEAR
HIGH NUCLEAR
WITH ACCIDENT
2025
2050
1975
2000
2025
2050
2075
2100
PRODUCTION OF COAL IS SPECIFIED IN UNITS OF PRIMARY DEMAND. PRODUCTION OF OTHER FUELS IS IN UNITS OF FINAL
ENERGY.
-------
4-19
A third lower C02~producing scenario is one in which electri-
fication is encouraged coupled with low solar and nuclear costs.
This is called the High Electric Baseline and features (1) increased
market penetration of electricity in each economic sector in the
OECD regions, and (2) the same production cost functions for solar
and nuclear as in the High Renewable and High Nuclear Baseline
scenarios. Higher market penetration would be accomplished, for
example, by greater use of heat pumps, electric boilers, and
electric cars, all encouraged by factors other than the relative
annualized costs of electricity and competing fuels.*
This scenario produces substantially higher electricity
demand but only slightly higher total energy use, than the Mid-
range Baseline, as shown in Figure 4-7. Only a small increase
in total demand occurs despite a decrease in the average regional
price of electricity in 2100 of 40 percent, compared to the Mid-
range scenario. Although this price difference is substantial,
the price of electricity is still higher here than other fuels
available in the Mid-range scenario. Since many consumers are
assumed to be using electrical equipment in this secenario irre-
spective of its price relative to other fuels, they would be
paying more for the same level of energy use estimated in the
Mid-range Baseline (since electricity costs more), thus their
level of demand decreases.
* These factors could be lower initial costs, greater reliability,
or better ease of operation associated with electrical equipment.
-------
FIGURE 4-7
HIGH ELECTRIC VS. MID-RANGE SCENARIOS: ENERGY USE CHARACTERISTICS
1600
1400
1200
£ 800
a.
400
200
FINAL ENERGY USE
MID-RANGE
HIGH ELECTRIC
1975
2000
2025
2050
2075
I
2100
1200
1000
800
600
400
200
ELECTRICITY PRODUCTION
MID-RANGE
HIGH ELECTRIC
1975
I
2000
2025
2050
I
2075
I
2100
I
W
O
£C
tc
600
500
400
300
200
100
UNCONVENTIONAL OIL PRODUCTION
MID-RANGE
— — HIGH ELECTRIC
COAL PRODUCTION
1200
1000
800
600
400
200
MID-RANGE
HIGH ELECTRIC
1975
2000
2025
2050
1975
2000
2025
2050
2075
2100
a/ PRODUCTION OF COAL IS SPECIFIED IN UNITS OF PRIMARY ENERGY. PRODUCTION OF OTHER FUELS IS IN
UNITS OF FINAL ENERGY.
-------
4-21
Figure 4-7 also shows a substantial reduction in the use of
coal and unconventional oil. Synthetic oil, however, remains at
about the same level as in the Mid-range Baseline. All of these
effects work together to produce a substantial reduction in CC>2
emissions — 33% by 2100.
The final low CC>2 baseline features high fossil fuel costs
and enhanced conservation. These factors work together to lower
overall energy demand; thus, this senario is called the Low
Demand scenario. The breakthrough and long-run reference prices
for coal, unconventional oil, and unconventional gas are each
increased by 50 percent. (In effect, this raises the long-run
supply curves for these fuels without changing the slope of
the curves.) The nonenergy costs of producing synfuels are
also increased by 50 percent. Conservation is enhanced by intro-
ducing an arithmetic increase in the "enhanced energy efficiency"
parameter of 1.0 percent per year for OECD cuntries (residential
and commercial sector), and moderately increasing the rate of
increase for the aggregate sector in other regions. (To illus-
trate the changes from the Mid-range Baseline, the parameter
index for 2100 is increased from 1.0 to 2.25 in the OECD sectors,
and from 1.99 to 2.25 elsewhere.)
These changes produce significant reductions in estimated
energy demand, as illustrated in Figure 4-8. Compared with the
Mid-range baseline, final energy demand falls about 24 percent
in 2050 and over 32 percent in 2100. Reductions in primary
-------
FIGURE 4-8
LOW DEMAND VS. MID-RANGE SCENARIOS: ENERGY USE CHARACTERISTICS £/
1400
1200
10001-
800|_
600
400
200
FINAL ENERGY USE
LOW DEMAND
MID-RANGE
600
500
400
300
200
100
LIQUIDS PRODUCTION
LOW DEMAND
MID-RANGE
1975
2000
2025
2050
2075
2100
1975
2000
2025
2050
2075
2100
I
NJ
NJ
GC
1200
1000
800
600
400
200
COAL PRODUCTION
—— LOW DEMAND
MID-RANGE
250
200
150
100
50
1975
2000
2025
2050
2075
2100
1975
GAS PRODUCTION
LOW DEMAND
— MID-RANGE
UNCONVENTIONAL GAS
2000
2025
2050
2075
2100
PRODUCTION OF COAL IS SPECIFIED IN UNITS OF PRIMARY ENERGY. PRODUCTION OF OTHER FUELS IS IN UNITS OF FINAL ENERGY.
-------
4-23
energy use are somewhat higher in 2050 (about 30 percent) but
somewhat lower lower in 2100 (about 26 percent). As discussed
in the next section, the reduction in CC>2 emissions are of a
comparable magnitude.
One higher CO2~producing baseline was explored. Since the
costs of all fossil fuels but conventional oil and gas are reduced,
it is called the High Fossil scenario. Final costs of production
(i.e., those in 2100) are reduced by 50 percent for unconventional
(shale) oil, unconventional gas, and coal. The costs of converting
coal and biomass to synfuels are also reduced by half, but non-
energy costs of synfuel production are unchanged.
Figure 4-9 summarizes the resulting fuel use patterns com-
pared with those of the Mid-range scenario. As shown, the increase
in total demand (resulting from lower prices after 2000) is satis-
fied largely by increased production of (1) synthetic oil and gas
from coal and (2) unconventional oil. Use of these high CO2~
emitting fuels raises total emissions by about 20% in 2100.
CO? and Atmospheric Responses
The GISS modeling results for the baseline scenarios are
illustrated in Figure 4-10. The variation in CC>2 emissions and
especially in atmospheric temperature change appears small.
Using the "time to increase by 2°C" measure, the differences
among the various baseline scenarios are negligible — less than
5 years. In other words, the temperature curves are essentially
idential through 2040. Even the difference in estimated temper-
-------
FIGURE 4-9
HIGH FOSSIL VS. MID-RANGE SCENARIOS: ENERGY USE CHARACTERISTICS S/
E
K
£
1800
1600
1400
1200
1000
800
600
400
200
FINAL ENERGY USE
-"— HIGH FOSSIL
— MID-RANGE
1975
2000
2025
2050
DC
1400
1200
1000
800
600
400
200
COAL PRODUCTION
HIGH FOSSIL
MID-RANGE
1975
2000
2025
2075
2100
2050
2075
800,-
700 -
600-
500-
400 .
300-
200.
100.
1975
LIQUIDS PRODUCTION
—- HIGH FOSSIL
— MID-RANGE
2000
2025
2050
2075
2100
GAS PRODUCTION
— HIGH FOSSIL
— MID-RANGE
500
400
300
200
100
2100
1975
2000
2025
2050
PRODUCTION OF COAL IS SPECIFIED IN UNITS OF PRIMARY ENERGY. PRODUCTION OF OTHER FUELS IS IN UNITS OF FINAL ENERGY.
-------
FIGURE 4-10
CO 2 MODELING RESULTS FOR ALTERNATIVE BASELINE SCENARIOS
INCREASE IN ATMOSPHERIC TEMPERATURE
C/J
LU
Ul
O
LU
Q
5.0
4.0
3.0
MID-RANGE
HIGH ELECTRIC
HIGH NUCLEAR
HIGH RENEWABLE
« » » HIGH FOSSIL
* A A LOW DEMAND
2.0
1.0
I
to
Ul
I I I I I I I T I 1 I I I
1980 1990 2000 2010 2020 2030 2040 2050 2060 2070 2080 2090 2100
CO 2 EMISSIONS
a: 60
cc
£ 50
1 40
cc
? 30
20
fsgpg
O
5
10
1980 1990 2000 2010 2020 2030 2040 2050 2060 2070 2080 2090 2100
-------
4-26
atures in 2100 varies by only about 0.7°C or less than 15 percent
of the projected Mid-range temperature. Clearly, conclusions
about the effectiveness of policy options which are reached in
this study will not be substantially affected by the choice of
baseline scenario.
OTHER BASELINE SENSITIVITY TESTS
In addition to specifying alternative energy use baselines,
the sensitivity of the principal model outputs to selected inputs
was tested separately. As noted earlier in this chapter, lower
GNP growth rates were tested (2.8 versus 3.8 percent per year)
for the less developed and developing regions for the period
2050-2100. Another test involved lowering income (or GNP) elas-
ticities of energy demand. Initial values of 1.0-1.4 in the
Mid-range Baseline were reduced uniformly to 0.85 for all regions
and all time periods.
Although changing each of these input variables reduced
energy demand by as much as 22 percent in 2100, the effects on
CC>2 emissions and concentrations and especially on atmospheric
temperature were substantially muted. Lowering GNP growth rates
after 2050 obviously did not affect the projected year of a 2°C
rise (2040 in the Mid-range Baseline), and reduced the estimated
temperature rise in 2100 by only 0.2°C (less than five percent).
Decreasing the income elasticity of demand likewise had no per-
ceptable effect on the 2°C year, and lowered the rise in 2100 by
less than 0.5°C.
-------
4-27
We conclude from these results that moderate changes to
GNP growth rates (post-2050) and to income elasticity of energy
demand values will not significantly alter the findings and
conclusions of our study.
POLICY OPTIONS
Policies selected for assessment are designed explicitly
to reduce emissions of (X>2 either indirectly by depressing
aggregate energy demand, or directly by shifting fuel-use
patterns toward fuels with low net emissions of CO2« Most
policy options examined possess some elements of each strategy.
TAXES ON CO-) EMISSIONS
The first set of policy options are based on taxing fuel use
proportionately to the fuel's net CO2 emissions per unit of energy.
Three variations were examined: (1) a tax only in the United Stated
(2) taxes in all OECD countries, and (3) taxes in all countries.
Tax schedules were specified to double the cost of the highest CO2
emitting fuel (unconventional oil):
Fuel Type Tax (percent)
Conventional Oil 41%
Conventional Gas 29
Unconventional (Shale) Oil 100
Unconventional Gas 29
Synthetic Oil 81
Synthetic Gas 86
Coal 52
All Others (solar, biomass, hydro) 0
Taxes of up to 300 percent were also investigated.
-------
4-28
Taxes were initiated in 2000 and were applied at both the
points of end use and production such that the combination was
sufficient to achieve the total percent taxation indicated
above.* In addition, fuel export bans were placed on the United
States (U.S. Tax scenario) and on all OECD countries (OECD Tax
scenario) to prevent the export of fuels from taxed to untaxed
regions, which would otherwise have undercut the global effec-
tiveness of the policy.
Energy Supply and Demand
Changes in total energy demand and in the use of selected
fuel types are illustrated in Figure 4-11 for each of the three
CC>2 tax scenarios. First, an overall dampening of worldwide
energy demand is apparent in direct relation to increases in
fuel prices as a result of the taxes. Second, a shift away from
high CC>2-emitting fuels is projected with one exception --
synthetic oil. Production of syncrude is depressed relative to
the Mid-range Baseline early in the next century, but exceeds the
baseline levels by 2075 for all tax scenarios. Apparently the
demand for liquid fuels remains high (especially in the transpor-
tation sector), and syncrude is selected over unconventional oil
to satisfy this demand. (Recall that the tax on syncrude is 81
* Due to the structure of the IEA model, negative taxes (sub-
sidies) had to be applied to biomass production to offset
the end use taxes on biomass and biomass-derived synfuels.
-------
FIGURE 4-11
CO 2 TAX POUCIES VS. MID-RANGE BASELINE SCENARIOS: ENERGY USE CHARACTERISTICS
a/
1400
1200
1000
800
600
400
200
FINAL ENERGY DEMAND
MID-RANGE
_ U.S. TAX
OECDTAX
WORLD TAX
UNCONVENTIONAL OIL
PRODUCTION
MID-RANGE
U.S. TAX
OECDTAX
WORLD TAX
SYNTHETIC OIL PRODUCTION
MID-RANGE
U.S. TAX
OECD TAX
WORLD TAX
1975 2000 2025 2050 2075 2100 1975 2000 2025 2050 2075 2100 1975 2000 2025 2050 2075 2100
300
250
(£. 200
cc
SI 150
SYNTHETIC GAS PRODUCTION
MID-RANGE
-._ U.S. TAX
. OECDTAX
WORLD TAX
IU
100
50
AVERAGE REGIONAL
PRICE OF UQUIDS
. MID-RANGE
U.S. TAX
• OECD TAX
WORLD TAX
14
12
10
8
6
4
2
AVERAGE REGIONAL
PRICE OF GASES
. MID-RANGE
U.S. TAX
• OECD TAX
' WORLD TAX
1975 2000 2025 2050 2075 2100 1975 2000 2025 2050 2075 2100 1975 2000 2025 2050 2075 2100
!/
PRODUCTION OF ALL FUELS IS SPECIFIED IN UNITS OF FINAL ENERGY.
I
N>
vo
-------
4-30
percent while the tax on unconventional (shale) oil is 100 per-
cent. ) Note also that much of the effect achieved by taxing CC>2
emissions occurs after the middle of the next century when
large-scale production of unconventional oil and synthetic fuels
is underway.
Figure 4-11 also reveals that the World Tax scenario is
much more effective in shifting energy demand and fuel-use pat-
terns than the other two scenarios. This is a direct reflection
of energy use levels in the U.S. and all OECD countries compared
with total worldwide levels. For example, in 2050 under the
Mid-range Baseline assumptions, the United States is projected
to account for 21 percent and all OECD countries 51 percent of
the world's energy consumption. By 2100, these levels are pro-
jected to fall to 14 and 34 percent, respectively.
Interestingly, none of the tax scenarios affects the use of
coal appreciably. The demand for solid fuels remains strong and
the level of C02 taxes investigated does not provide sufficient
cost advantage for biomass to capture a substantial share of
this market.
Tripling the level of taxation on all fossil fuels world-
wide (i.e., 300 percent on unconventional oil and proportional
increases for the others) enhances each of the fuel use trends
shown in Figure 4-11. Projected energy demand in 2050 is just
over 300 EJ (60 percent of the Mid-range level), synfuel produc-
tion is delayed until after 2050, and even coal production is
-------
4-31
depressed (by over 50 percent relative to the Mid-range level).
Changes by 2100 are even more dramatic. However, the penalty
paid for improved effectiveness in reducing CC>2 emissions is
a substantial rise in average regional energy prices: approxi-
mately 60 percent for liquids, 40 percent for gas, and 20 per-
cent for solids compared with the Mid-range Baseline price
schedules in 2050.
CO2 and Atmospheric Responses
The resulting CC>2 emissions and atmospheric temperature
trends are shown in Figure 4-12. As suspected from the fuel-
use effects, only the World Tax scenario achieves a significant
reduction in CC>2 emissions and, even here, only toward the end
of the next century. (Emissions are reduced from 5-18 percent
in 2050 and from 10-42 percent in 2100.) In terms of changes
in atmospheric temperature, the differences between the tax
scenarios and the Mid-range Baseline are even less dramatic.
Only the World Tax scenario appears to affect the timing of a
2°C increase in temperature and only on the order of a few years.
Even tripling taxes worldwide delays a 2°C rise by just over 5
years. Temperature differences are more pronounced in 2100, but
even this far into the future, the maximum estimated reduction
is only about 0.7°C. Tripling taxes is more effective but not
overwhelmingly so (a lowering of temperature in 2100 by perhaps
-------
CO
UJ
IU
EC
13
Ul
O
5.0
4.0
3.0
2.0
1.0
4-32
FIGURE 4-12
CO2 MODELING RESULTS FOR TAX POLICIES
AND MID-RANGE BASELINE SCENARIOS
INCREASE IN ATMOSPHERIC TEMPERATURE
MID-RANGE
U.S. TAX
OECD TAX
WORLD TAX
1980 1990 2000 2010 2020 2030 2040 2050 2060 2070 2080 2090 2100
CO2 EMISSIONS
tc.
UJ
a.
u.
O
CO
I
O
(S
50
40
30
20
10
MID-RANGE
US TAX
OECD TAX
WORLD TAX
1980 1990 2000 2010 2020 2030 2040 2050 2060 2070 2080 2090 2100
-------
4-33
FUEL BANS
A more direct approach to slowing the rate of CC>2 growth
is to prohibit all uses of selected high CC>2-emitting fuels.
Four separate combinations of fuel bans were investigated: (1)
coal alone, (2) unconventional (shale) oil alone, (3) shale
oil and synthetic fuels, and (4) shale oil and coal. The ban
on coal is phased-in between 1980 and 2000. To obtain the max-
imum effect from these policies, worldwide cooperation among
governments is assumed.
Energy Supply and Demand
Figure 4-13 shows the energy patterns produced by the four
fuel ban scenarios. Due to prohibitions on the indicated fuels,
energy prices in general are bid upwards by consumers attempting
to satisfy their demands. Price increases for liquid fuels are
especially dramatic (over a 300 percent increase) for the scenario
banning shale oil and synthetic fuels. Solid fuel prices are
increased the greatest for the two scenarios banning coal (80-
120 percent increase). (Gas prices also rise relative to the
Mid-range Baseline but in a somewhat muted fashion). The ulti-
mate effects are substantial decreases in total energy demand
compared with the reference baseline, from 20 to almost 80
percent in 2100. The two scenarios banning coal achieve these
reductions earlier than the other scenarios.
-------
4-34
FIGURE 4-13
FUEL BANS VS. MID-RANGE BASELINE SCENARIOS: ENERGY USE CHARACTERISTICS
FINAL ENERGY USE
K
£
3
1400
1200
1000
800
600
400
200
700
600
— MID-RANGE
— NO SHALE
• — NO SHALE, NO SYNFUELS
—NO SHALE. NO COAL ,
••« NO COAL / // 50°
100
SYNFUEL PRODUCTION
—— MID-RANGE
—— NO SHALE
......... MO SHALE, NO COAL
...... NO COAL
1400
1200
COAL PRODUCTION
• MID-RANGE
—— NO SHALE
NO SHALE.
NO SYNFUELS
1975
2000 2025 2050 2075 2100 1975 2000 2025 2050 2075 2100 1975 2000 2025 2050 2075 2100
BIOMASS (AS SOLID FUEL) PRODUCTION
240
200
160
cc
a. 120
HI
o.
3 80
40
—— MID-RANGE
,—— NO SHALE
----- NO SHALE, NO SYNFUELS, *
60
=J 50
AVERAGE REGIONAL
PRICE OF LIQUIDS
MID-RANGE
r ___ NO SHALE
NO SHALE. NO SYNFUELS
-«—— NO SHALE, NO COAL
4-
60
50
40
30
20
10
AVERAGE
PRICE OF SOLIDS
MID-RANGE
___NO SHALE
—NO SHALE, NO SYNFUELS
«——NO SHALE, NO COAL ^
...... NO COAL
„*••*•
....—ViVV'*"* * *
a/
1975 2000 2025 2050 2075 2100 1975 2000 2025 2050 2075 2100 1975 2000 2025 2050 2075 2100
PRODUCTION OF COAL AND BIOMASS IS SPECIFIED IN UNITS OF PRIMARY ENERGY. PRODUCTION OF SYNFUELS IS IN UNITS OF FINAL
ENERGY.
-------
4-35
Production patterns for individual fuel types provide addi-
tional insights. Synfuels are allowed under three scenarios.
When shale oil is banned, synthetic oil production grows to meet
demands for liquid fuels. However, when coal is also banned,
synfuel production is limited by the availability (and price) of
biomass. Thus, synfuel levels drop relative to the Mid-range
Baseline. Similarly, the production of coal is affected by the
demand for coal-derived synthetic oil and gas; when synfuels are
banned, coal production drops below the Mid-range Baseline levels.
(This is also reflected in the constant or slightly decreasing
price of solid fuels.)
Biomass and coal are direct competitors both as solid fuels
and as raw materials for synfuels. Whenever coal is unconstrained,
it has a substantial competitive edge in almost all regions. How-
ever, when coal is banned, the full potential of biomass to satisfy
demands for liquids, gases, and solids worldwide can be assessed.
Figure 4-13 reveals that, in the "No Shale, No Coal" scenario,
biomass accounts for about 225 EJ of synthetic liquid and gas
production and about 160 EJ of solid fuel production in 2100.
Together, this represents almost 60 percent of total energy
demand projected for this scenario.* The penalty for relying
* The worldwide potential of energy farms to produce biomass for
energy has been estimated at between 237 and 3374 EJ, depending
on the types of crops planted and the agricultural practices
employed. Urban waste may add another 100 EJ potential by 2100
(Reilly, et al., 1981). These estimates are considerably higher
than the biomass resource estimates in Appendix A (Table A-2).
However, the latter assume no dramatic change in the availability
of coal, and thus implicitly incorporate considerations of cur-
rent economic feasibility. The resource availability estimates
used in the IEA/EPA scenarios are intended to reflect extreme
circumstances.
-------
4-36
on bioraass is reflected in the higher price of solid fuels —
approximately $5.25/EJ in 2100 compared to the reference price
of $2.25.
CO? and Atmospheric Responses
The time course of CO2 emissions and atmospheric tempera-
ture for the fuel ban scenarios are shown in Figure 4-14. The
changes in energy demand and fuel use discussed above translate
into significant decreases in CC>2 emissions. The most stringent
prohibition scenario (coal and shale oil bans) achieves absolute
reductions in CC>2 emissions over time; emissions in 2100 are
slightly more than 1000 gigatons of carbon worldwide compared to
about 4700 in 1975. Moreover, reductions begin very early in
the 120-year time period due to the ban on coal phased-in
between 1980 and 2000. The "No Shale, No Synfuels" scenario
is less effective in terms of total emissions avoided, but does
achieve reductions beginning about 2020 and totaling about two-
thirds of the projected 2100 emissions in the Mid-range Baseline.
Banning just shale is less effective although it still achieves
almost a 60 percent reduction in CC>2 emissions in 2100 compared
with the baseline emissions. Finally, much of the effectiveness
of a "coal only" ban is eroded after 2040 when shale oil comes
on-line.
To further illustrate the effect of fuel bans on reducing
C02 emissions, Figure 4-15 shows changes in emissions over time
for two scenarios in each of the nine geographic regions. In the
-------
FIGURE 4-14
CO2 MODELING RESULTS FOR FUEL BANS AND MID-RANGE BASELINE SCENARIOS
U
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I I I I I I I I I I I
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-------
FIGURE 4-15
GEOGRAPHIC DISTRIBUTION OF CO2 EMISSIONS FOR SELECTED
FUEL BANS AND THE MID-RANGE BASELINE SCENARIOS
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-------
4-39
earliest year (2000) when only a ban on coal reduces emissions,
the effects of the ban fall on regions roughly in proportion to
their emissions of CC>2 in the Mid-range Baseline scenario.
Exceptions to this rule are Region 6 (the Middle East), which
has very little coal, and Region 8 (Latin America), which has a
large biomass potential and is given credit for exporting biomass-
derived fuels. By 2050, the effect of a coal ban becomes more
uneven, as the coal-rich regions — Region 1 (U.S.) and Region 4
(U.S.S.R. and Eastern Europe) — show proportionately the largest
drop in projected emissions. By 2100, these two regions have
reduced emissions by about 95 and 98 percent respectively,
relative to the Mid-range Baseline projections. (Africa and
Latin America both show zero net emissions due to the IEA model's
accounting scheme for exported biomass energy.)
The pattern of impacts from a ban on shale oil and synfuels
is similar — those regions with large deposits of shale oil or
coal are affected the most. Thus, by 2100, Region 1 (U.S.),
Region 2 (Canada and Western Europe), and Region 4 (U.S.S.R and
Eastern Europe) are forced to reduce emissions by the greatest
percentage. In the opposite sense, regions with large capaci-
ties for biomass production are also disadvantaged by the ban
on synfuels and thus show higher emission levels than those in
the coal ban scenario.
-------
4-40
Looking at the atmospheric effect of reductions in C02
emissions associated with fuel bans (Figure 4-14), only the
scenarios which ban coal affect the timing of a 2°C rise in
atmospheric temperature. For these, however, the size of the
effect is significant — the estimated 2°C year is delayed from
roughly 2040 in the baseline to approximately 2055 in the coal
ban scenario, and to 2065 under coal and shale oil bans. The
scenario featuring a ban on shale and synfuels appears to delay
the 2°C date by no more than 5 years, while a ban on shale alone
is totally ineffective by this measure.* All prohibition
scenarios achieve substantial reductions in temperature rise by
2100, with the most stringent scenario achieving almost a 50
percent reduction.
Based on these results, a clear distinction between medium-
term and long-term strategies emerges. The scenarios in which
coal is banned show significant medium-term effects (delay in a
2°C rise) since the ban affects fuel use and CC>2 emissions in
the early years (by 2000 and thereafter). Bans on synthetic
* In other words, although banning shale alone is not effective
in delaying a 2°C rise, banning shale in addition to coal
appears to add about 10 years to the "coal only" delay (2055
to 2065). These results at first appear contradictory but
can be reconciled; a prohibition on coal encourages an earlier
emergence of shale oil (about 100 EJ of unconventional oil
are produced in 2050 in the "coal only" scenario compared with
only 10 EJ in the Mid-range Baseline), presumably because the
lack of coal-derived synthetic oil makes shale oil more cost-
competitive.
-------
4-41
fuels and unconventional oil only become effective when these
fuels would otherwise come on-line. Thus, policies incorpor-
ating synfuel and shale oil bans reduce long-run temperature
increases, but not the timing of a 2°C rise.
It is also useful to note that a simultaneous ban on coal
and synfuels would be duplicative; no additional reduction in
either CO2 emissions or atmospheric temperature is achieved by
prohibiting synfuels once coal is banned. Moreover, allowing
the production of synthetic liquids and gases while prohibiting
coal will provide for a biomass-based synfuel industry, thus
partially satisfying the demand for liquid fuels in a manner
that depresses CO2 emissions.
SUMMARY
Of the various energy policies designed to slow the rate
of atmospheric warming over the next century that were examined
in this analysis, only two have been demonstrated to effectively
delay the timing of 2°C rise in temperature. Both include a ban
on the use of coal which becomes fully effective in 2000. This
ban (1) reduces demand for solid fuels by raising their price,
and (2) stimulates the use of biomass as a coal substitute.
Both effects reduce the aggregate amount of CC>2 emitted between
now and the middle of the next century. When a ban on coal is
combined with a ban on shale oil, the projected 2°C warming may
be delayed by perhaps 25 years.
-------
4-42
Banning shale and synthetic fuels alone will produce a
slowing of temperature rise in the second half of the next
century. If coal is also banned, prohibitions on synthetic fuel
production are not necessary since all synfuels would be derived
from biomass. The effectiveness of fuel bans in lowering the
projected temperature in 2100 is significant for all prohibition
policies studied, and greatest for policies which ban both coal
and shale oil.
The imposition of fuel taxes applied in proportion to CC>2
emission characteristics of individual fuels appears to be much
less effective than outright fuel bans. Taxes of several hun-
dred percent in magnitude would be needed to substantially
depress demand. Even then, the distinction among different type
of fuels in terms of CC>2 emission characteristics is not nearly
as sharp as placing bans on selected fuels. Thus, fuel taxes do
not appear to be effective medium-term policy options, and would
be effective in the long-run only if taxes were very high.
Regardless of which general policy approach is under con-
sideration, any hope of success requires cooperation among at
least the major energy consuming and producing nations. Over
time, almost all nations will fall into this category. Without
worldwide cooperation, international fuel trading and uncon-
strained use of fuels in non-cooperating countries would impede
the effectiveness of any policy.
-------
4-43
These findings must be placed in the context of uncertain-
ties surrounding the relationships between (1) emissions and
atmospheric concentrations of CC>2 (that is, the nature of the
carbon cycle), and (2) atmospheric temperature and CC>2 concen-
trations (that is, the actual temperature equilibrium for doubled
CC>2). The latter appears to be the more important, and introduces
substantial variability in projections of temperature rise. This
variability is on the order of 35-40 years in the estimate of when
a 2°C warming will occur. Of at least equal significance are
uncertainties regarding future levels of other greenhouse gases
and their effect on atmospheric temperature. These uncertainties
may account for another 40-45 years in the variability of the
estimated 2°C warming date.
-------
CHAPTER 5
THE ECONOMIC AND POLITICAL FEASIBILITY OF ENERGY POLICIES
The analysis in Chapter 4 clearly shows that only policies
that ban coal, or coal and shale oil, would significantly delay a
warming of 2°C or more. Furthermore, a ban on coal and shale oil
would be effective in reducing the temperature rise in 2100. This
chapter examines whether these policies are also economically
and politically feasible.
The economic implications of banning coal and shale oil are
likely to be significant. Prohibitions on using these fuels
would necessitate a fundamental change in fuel use and would most
likely affect all sectors of the world economy. It would dampen
economic growth by causing a shift to more expensive fuel substi-
tutes. The asset value of existing coal and shale oil resources
would decline, as might the value of facilities supporting the
production, transportation, and use of fossil fuels due to pre-
mature retirement. On the other hand, the value of alternative
fuels would be enhanced by coal and shale oil bans.
The economic impact of these policies would affect different
countries in very different ways. Impacts would be largest in
developed economies heavily dependent on fossil fuels or in
countries with large coal and shale oil deposits. Higher energy
prices could also severely constrain the economic growth of
developing and less developed countries. Such economic hardships
-------
5-2
could be mitigated by anticipating and planning for changes in
energy supplies.
This chapter examines each of these issues. In particular,
it looks at our current and likely future commitment to coal and
shale oil, and the economic consequences of banning their use.
Ideally, this analysis would be based on a detailed model of the
world economy capable of translating changes in the energy sector,
into changes in inflation, economic growth, income levels, and
other relevant economic indicators. Unfortunately> no current
model provides the desired level of detail and specificity.
Given this limitation, we have focused on specific aspects of
likely economic impacts and have tried to illustrate the magni-
tude of potential effects through a series of examples.
EFFECTS OF POLICIES ON COAL RESOURCES
A nation's natural resources can constitute a significant
percentage of its wealth. An obvious example is the gold and
diamonds of South Africa. Similarly, oil and gas resources have
created enormous wealth for Mideast nations. Vast coal deposits
in several nations are considerably valuable now, and could be
even more valuable in the years to come.
GLOBAL DISTRIBUTION OF COAL
Most of the world's known coal resources are found in the
Northern Hemisphere. The Southern Hemisphere contains fewer
large sedimentary basins where coal typically forms, and has
-------
5-3
not been as extensively explored because of limited regional
demand. However, many developing countries may increase their
rate of exploration in anticipation of increased industrial
activity and in pursuit of greater energy independence. Hence,
estimates of total coal resources are very likely to increase in
the future.
Figure 5-1 provides a summary of coal resources throughout
the world. Coal resources total approximately 10 trillion metric
tons of coal equivalent (mtce) worldwide, based on a compilation
of estimates from various international organizations. As shown,
the Soviet Union ranks first, with 44 percent of total resources,
and the United States, China, and Australia are the next three
leading nations. The top three countries alone contain 83 percent
of the world's total coal resources.
Figure 5-2 contains estimates of "economically recoverable"
coal resources, that is, of coal reserves. The world's recover-
able reserves are estimated to be 688 billion tons — only 6.9
percent of known resources. Yet, at 1980 production levels, this
recoverable coal still represents about 258 years of supply. The
United States has the largest amount of reserves, followed closely
by the U.S.S.R. and China. Combined, these three countries have
some two-thirds of the world's recoverable coal reserves.
These data on coal resources and reserves have important
implications for CC>2 mitigation strategies. The economic burden
of any international agreement to limit the use of coal will fall
-------
5-4
FIGURE 5-1
COAL RESOURCES
ALL OTHER
NATIONS
TOTAL: 10.000 BILLION MTCE
FIGURE 5-2
RECOVERABLE COAL
RESERVES
TOTAL: 688 BILLION MTCE
SOURCE: UNITED NATIONS, 1981, 1979 YEariBOOK OF WORLD ENERGY STATISTICS. AND FEDERAL INSTITUTE FOR GEOSCIENCE AND
NATURAL RESOURCES, 1980, SURVEY OF ENERGY RESOURCES. AS REPORTED IN GROSSLING, 1981, WORLD COAL RESOURCES.
-------
5-5
\
primarily on three nations — the U.S.S.R., China, and the United
States. Moreover, the exclusion of any one of these nations
would permit the use of enough coal to erode the effectiveness
of any CC>2 control policy based on banning its use.
CHANGES IN VALUE OF COAL RESERVES
Any substantial shift away from coal would have a dramatic
effect on the value of these resources. A ban (or even a tax)
on coal would reduce the demand for these resources and there-
fore depress their asset values. Countries and people owning
deposits of the affected fossil fuels would lose the revenues
these resources would otherwise earn. In addition, the value
of the infrastructure used to produce, transport, and use these
fuels would also decline if these facilities are prematurely
retired.
To some extent, the loss in value of these resources would
be offset by the enhanced worth of substitute fuels and techno-
logies. Whether the alternatives are solar, nuclear, biomass,
or some combination thereof, the value of these technologies
should increase in direct proportion to their increased demand.
Although it is clear which nations would lose from prohibitions
against certain fossil fuels, it is less clear which ones would
gain. Who the winners and losers are will play an important
role in determining the feasibility of international CC>2 policies.
-------
5-6
Estimating the magnitude of the loss in asset value is
straightforward in concept, but difficult in practice. The diffi-
culty arises in estimating the value of the coal deposits with
and without a coal ban. This value should be based on the future
stream of production levels, forecasted production costs, and
future prices. It would vary based on expectations of how long
the ban would be imposed, the location of each deposit, and a
host of other factors.
An approximation of lost asset value can be obtained by
comparing production levels and prices of coal in the two rele-
vant scenarios — the Mid-range Baseline and either one of the
coal ban scenarios — and ignoring the other relevant variables.
This'provides an estimate of lost revenue, a portion of which
reflects profits from coal, and thus is a measure of the loss in
asset value. Using a real discount rate of 5 percent, the lost
revenues are estimated to be approximately $2.8 trillion (in 1980
dollars). Using a real discount rate of 10 percent drops this
estimate to just over $700 billion.* In either case, however,
the lost value would be enormous. Moreover, this loss is under-
stated because it does not include the decline in value of the
coal resources that would have been used after 2100 in the absence
of a ban.
* Many economists argue that the appropriate discount rate for
long-run resources (or future investments) should be close to
zero to fairly reflect the interests of future generations.
-------
5-7
CHANGES IN FUEL PRICES
Another indication of the impact of a ban on coal is the
magnitude of the changes in energy prices resulting from these
policies. For example, in the year 2050, the projected price of
solids (coal or biomass) would increase from about $1.40/GJ in
the Mid-range scenario to about $3.10/GJ (just biomass) if a ban
on coal were adopted. If oil shale is also banned, the price of
liquid fuels in the Mid-range Baseline similarly would be bid
upwards, almost doubling by 2100.
Higher prices for energy encourage increased efficiency and
therefore reduce overall demand. However, higher prices also
require that the production and use of energy absorb a greater
portion of total wealth. As a result, less capital is available
for other economic activities.
CAPITAL INVESTMENTS IN COAL
In addition to the loss in value of coal resources, other
aspects of the coal "market chain" may also be affected. The
market chain provides a useful conceptual framework for identi-
fying and analyzing capital investments directly linked to the
use of that resource. The typical coal market chain consists of
three components:
• extraction — removing the fossil fuel from the, earth
either through a surface or deep mine;
• transportation/preparation — moving the fossil fuel
from its resource location to a consuming market and
preparing it for consumption, including coal washing;
and
-------
5-8
• conversion — using the prepared fossil fuel directly
as a heat source or indirectly to generate electricity.
A comprehensive analysis of the costs involved in banning
coal would require extensive knowledge of local conditions in
each country. It is thus considerably beyond the scope of this
study. Instead, this section looks at two specific market chains
and a study of aggregate future coal investments to illustrate
the magnitude of capital invested in extracting, moving, preparing,
and converting coal. These chains involve moving coal from the
western United States for use in (1) a power plant in Japan and
(2) a power plant in the southwestern United States.
Table 5-1 summarizes the approximate investment necessary
to establish a coal chain between a western United States mine
and a Japanese 800-megawatt power plant. The total capital
invested in the chain is about $1.2 billion (in 1980 dollars),
with nearly 75 percent of this total associated with the power
plant. Hence, for each short ton of coal traded annually between
the United States and Japan related to this particular chain,
approximately $471 of capital will have been invested.
The capital investment required for a domestic U.S. coal
chain is almost as much as the above example (Table 5-2).
Interestingly, even with the use of a capital-intensive slurry
pipeline to move western coal to a West South Central market,
the estimated share of total capital represented by the power
plant is over 80 percent.
-------
5-9
TABLE 5-1
Facility Required:
APPROXIMATE CAPITAL INVESTMENT FOR INTERNATIONAL COAL CHAIN:
WESTERN UNITED STATES TO JAPANESE POWER PLANT
(MILLIONS OF 1980 DOLLARS)
Mine
25% capacity
of a 10-million
ton/yr. mine
Trains
3.9
unit trains
S/
Seaport
25% capacity
of a seaport
a/
4.9
ships
Power Plant
One
800-MW power plant
Useful Life:
20 years or
more
15 years or
more
30 years or
more
15 years
45 years or
more
Initial Capital Investment:
$33
$42
$39
$195
$877
Total Coal Shipped
Total Initial Capital Investment
Capital Investment Per Ton-Year
2.52 Million Short Tons/year
$1,186 Million
$471
a/ Facility required and capital investment are ICF interpretations of data reported in Coal
to the Future, Report of the World Coal Study, WOCOL, 1980, Figure 8-2, page 205.
Source: ICF Assessment, 1983
- Bridge
-------
5-10
TABLE 5-2
APPROXIMATE CAPITAL INVESTMENT FDR DOMESTIC COAL CHAIN:
WESTERN UNITED STATES TO WEST SOUTH CENTRAL POWER PLANT
(millions of 1980 Dollars)
a/
Mine Slurry Pipeline Power Plant
Facility Required: 25% Capacity 10% Capacity One 800-MW
of 10-million of 24.75-million power plant
ton/year ton/year
mine 1,400-mile pipeline
Useful Life: 20 years About 30 years 45 years
or more or more
Initial Capital $33 $135 $877
Investment:
Total Coal Shipped =2.52 million Short
Tons/Year
Total Initial Capital Investment = $1,045
Capital Investment Per Ton-Year = $415
a/ Slurry pipeline capital costs per ton are the low assumption from ICF
report to U.S. Department of Energy entitled The Potential Energy and
Economic Impacts of Coal Slurry Pipelines, January 1980, Table C-7,
page C-48 (estimates for pipeline from Wyoming to Arkansas/Oklahoma/
Louisiana).
Source: ICF Assessment, 1983
-------
5-11
These two examples suggest that the dominant component of
any future capital invested in the use of coal will be the power
plants used in generating electricity. Moreover, coal-fired
power plants cannot easily be converted to nonfossil fuels
(e.g., nuclear) and, once built, they have a relatively long
life. Some of the new coal-fired plants now under construction
and scheduled for operation by 1990 may still be operating in
2050. Thus, to minimize the economic impact, any policy banning
the use of coal would have to be applied prospectively to the
construction of new facilities.
The extent to which capital is invested in coal market
chains will depend on future demand for coal. The World Coal
Study (WOCOL) provides the most comprehensive, although arguably
optimistic, analysis of both demand and investment. This study
concluded that approximately 740 GW of new capacity would be
built in OECD countries from 1977 to 2000, with the United
States responsible for over half of that increase (see Table
5-3).
Using WOCOL1s prediction of the level of future OECD
economies, the likely capital committed to coal market chains can
be put in perspective (Table 5-4). This table takes into account
the costs of mining, transporting, and burning coal at power
plants. It does not include industrial use of coal. Nonethe-
less, over one trillion dollars or approximately 2.3 percent of
the projected total OECD economy — would be committed to the
-------
5-12
Table 5-3
WOCOL FORECASTED NET ADDITIONS OF COAL-FIRED
POWER PLANTS IN OECD COUNTRIES: 1977-2000
OECD Countries
Australia
Canada
Denmark
Finland
France
Germany, F.R.
Italy
Japan
Netherlands
Sweden
United Kingdom
United States
Other Western Europe
OECD TOTAL
Cumulative Coal-Fired Capacity Additions
Capacity Capital Investment
(GW) (billions of 1980 Dollars)
49
49
10
4
20
27
21
48
16
12
10
423
53
740
61
61
12
4
25
34
26
61
20
15
12
533
67
931
Source: Coal-Bridge to the Future, Report of the World Coal
Study (WOCOL), Ballinger, Cambridge, 1980, Table 8-3,
page 215.
-------
5-13
Table 5-4
WOCOL FORECASTED CUMULATIVE COAL CHAIN INVESTMENTS
a/
FOR WOCOL COUNTRIES IN OECD: 1977-2000
Cumulative Capital
(billions of 1980 Dollars)
TOTAL ECONOMY
COAL CHAIN COMPONENTS
Supply Facilities
Mines
Inland Transport
Ports
Ships
47,923
133
58
18
45
Consumption Facilities
Electric Power Plants
866
Total 1,120
COAL CHAIN AS PERCENT OF TOTAL ECONOMY 2.3%
a/ Consists of the following countries: Australia, Canada,
Denmark, Finland, France, Federal Republic of Germany,
Italy, Japan, Netherlands, Sweden, United Kingdom, United
States.
Source: Coal-Bridge to the Future, Report of the World Coal
Study (WOCOL), Ballinger, Cambridge, 1980, Table 8-1,
Table 8-3, pages 212-215.
-------
5-14
coal market chain during this time period. This example further
illustrates the size of the potential economic dislocation if a
ban on the use of coal is adopted by the turn of the century.
EFFECTS OF BANS ON SHALE OIL AND SYNFUELS
The examples used until now have focused on coal because
the results in Chapter 4 indicate that, if we are to signifi-
cantly delay a 2°C rise in temperature, a ban on coal by the
year 2000 is the only effective means of accomplishing that end.
Longer run temperature concerns extend beyond coal to include
prohibitions on shale oil and synfuels as an alternative to coal.
Coal liquifaction would, of course, be prohibited by a ban
on the use of coal. Similarly, a future ban on shale oil would
affect very few existing facilities. The purpose of examining
their production costs is to illustrate the quantity of required
capital and the expected useful life of these facilities in the
absence of future bans on coal and shale oil. If prohibitions
are instituted soon, the primary loss would be the research and
development costs invested in these industries to date. Moreover,
if the industries do reach commercialization, future efforts at
limiting use of their products would prove more difficult to
implement and may involve premature retirement of the associated
infrastructure.
Although costs for producing shale oil remain somewhat
speculative, the initial capital costs for a facility producing
50 thousand barrels of oil per day are likely to be about $2.85
-------
5-15
billion (1980 dollars). At an assumed heat content of 5.8 million
Btu per boe and 19.91 million Btu per metric ton of coal, the
cost of this shale oil facility is about $537 per annual mtce
output (ICF, 1983).
Using the same assumptions, the capital investment in a
coal liquifaction plant would be over $967 per annual mtce out-
put or a total of $5.6 billion (1980 dollars) for a 50 thousand
barrel per day facility (ICF, 1983). Each facility has an expected
useful life of thirty years.
Producing energy from shale and coal involves far more com-
plex technologies than those now used in producing oil or gas.
As a result, the start-up time of these projects is considerably
longer, the capital involved is far greater, and, generally, the
expected life is longer. These factors would severely limit
society's flexibility and increase its costs should future
policies limit the use of coal liquifaction and shale oil pro-
duction after these industries have become commercialized.
OTHER IMPEDIMENTS TO POLICY IMPLEMENTATION
The long life cycles of energy projects complicate the
problem of developing an effective response to the threat of
rising CO2- Whether that response involves adaptation or pre-
vention, the earlier a concerted strategy is implemented, the
lower the risks and costs of dealing with the CC>2 problem. Yet
the selection of a particular response can occur only after
several time-consuming preliminary steps have been taken:
-------
5-16
scientists and other researchers must provide substantial and
convincing evidence of the likely occurence and effects of the
greenhouse warming; an international agreement must be reached
specifying a consensus response to the problem; and this response
must be implemented (see Figure 5-3). Until these steps are
completed, few, if any, significant actions are likely to be
taken by nations concerned with rising CC>2 levels.
Figure 5-3
PROCESS LEADING TO ACTION
Consensus that
Greenhouse Warming
Must be Addressed
— >
Negotiate International
Accord which Defines
Appropriate Response
— >
Implement
Response
Measures
Chapter 2 of this report discussed efforts to isolate, from
the record of general climatic trends, any warming directly
attributable to greenhouse gases. Some researchers anticipate
that, by the beginning of the next decade, they will have suc-
cessfully demonstrated the magnitude of the relationship between
warming and the concentration of greenhouse gases. Initial
recognition by individual researchers, however, falls far short
of an international scientific consensus.
Efforts at reaching a consensus among political leaders to
act on the CO2 problem may prove even more difficult. A number
of international organizations including the World Meterological
-------
5-17
Society, the International Institute of Applied Systems Analysis,
and the United Nations Environment Program, have been actively
researching the problem, and have convened several conferences
during the past decade. Despite these activities, the prospects
for any future international accord remains uncertain. In
general, environmental issues have not readily produced an
international consensus. Acid rain and stratospheric ozone
depletion are two recent examples where transboundary pollutants
were involved, and where no international consensus on appropriate
responses was forthcoming. In these cases, as is true with CC>2,
countries are able to point to lingering uncertainties in the
scientifip evidence as the basis for inaction or delay.
Economic considerations may also play a role in the failure
to reach a consensus. In the case of both acid rain and ozone
depletion, some countries would be required to incur greater
costs than others. As the analysis of fossil fuel resources
presented earlier in this chapter clearly illustrates, this will
almost certainly be true should there be a future ban on coal or
shale oil.
The problem of inequitable distribution of costs and bene-
fits is even more acute for CO2~induced climate change, since the
consequences from such changes will differ dramatically from
country to country. In fact, some areas of the world are likely
to experience more desirable temperatures and increased rain-
fall, and therefore would benefit from rising CC>2. Ironically,
-------
5-18
as general circulation models improve, more information on
regional climate effects may further complicate the issue by
better identifying the winners and losers throughout the world.
Carbon dioxide may also become a cause of conflict between
developed and developing nations. Developed nations are cur-
rently most dependent on fossil fuels and generally possess the
largest resource base. They have the most to lose by accepting
a policy which limits the use of these resources. In contrast,
developing nations are most in need of inexpensive energy sup-
plies to provide food and to improve their standard of living.
According to the IEA/EPA model projections used in this study,
a large percent of the future increase in C02 emissions will be
the result of population and economic growth in developing
nations. In terms of equity, however, their contribution should
probably be balanced against past increases which overwhelmingly
were the product of industrialization in the developed nations.
One international conference has already proposed that developed
countries limit their CC>2 emissions to allow for greater fossil
fuel consumption by developing nations, while still limiting
overall emissions (Bach, 1980).
Given these competing interests, the future of any inter-
national accord remains, at best, a distant prospect. Unfortu-
nately, the findings and conclusions of this study indicate
clearly that only an international response will be effective
in delaying significant temperature change.
-------
5-19
SUMMARY
The above illustrations fall far short of a complete eco-
nomic and political feasibility analysis. They do, however,
provide considerable support for the conclusion that policies
banning the use of coal are unlikely to be adopted. The magni-
tude of the economic disruptions and need for a consensus among
the United States, China, Russia and the developing nations are
major hurdles to the adoption of a worldwide coal ban. A ban
on shale oil or on synfuels per se may be more tractable since
large scale production of these fuels has not yet begun. But,
even here, international cooperation is far from assured.
-------
CHAPTER 6
NONENERGY OPTIONS FOR CONTROLLING CO? EMISSIONS
Although most discussions of ways to reduce a greenhouse
warming focus on manipulating fuel use, researchers have proposed
several dramatically different approaches. These include con-
trolling CC>2 emissions at the source, sequestering CO2 from the
atmosphere, and reducing the amount of solar radiation received
at the earth's surface. Each of these alternatives is reviewed
in this chapter. Technical and economic feasibility, and poten-
tial effectiveness are assessed.
OPTIONS FOR CONTROLLING CO? EMISSIONS
Capturing CO2 from smokestacks would be a more direct means
of limiting its buildup in the atmosphere than switching to alter-
native energy sources. Many countries have successfully used
emission controls to limit the adverse effects of a variety of
pollutants from industrial processes. Firms are frequently
required to install control equipment or alter production pro-
cesses to reduce emissions below quantities that will harm the
public's health or welfare.
A plan to control CO2 emissions would appear attractive for
several reasons. First, if the CO2 problem could be remedied
through emission controls, there would no longer be any need to
consider potentially disruptive changes in fuel-use patterns.
-------
6-2
Alternatively, controlling CC>2 emissions could be an easier means
of .accommodation than making the required social and economic
adaptations to a warming climate. Second, requiring those sources
emitting carbon dioxide to bear the burden of controlling their
emissions represents an equitable solution to the problem. Third,
an emission control approach would satisfy those who favor a tech-
nologic "fix" to environmental problems. Finally, the potential
to quickly install controls on many sources of CC>2 would allow us
to become more certain about the severity of the CC>2 problem
before taking action.
Applying pollution controls (scrubbers) on major stationary
sources tp limit CC>2 emissions was first proposed by C. Marchetti
in an article in Climate Change in 1977. Once CC>2 was captured,
Marchetti proposed to inject it deep into the ocean where it
would be carried to lower layers by natural currents. Entrapped
CC>2 would thus be removed from the atmosphere for centuries.
Brookhaven National Laboratory (Albanese, 1980) examined
several alternatives for controlling and disposing of carbon
dioxide from coal-fired power plants. These plants, however,
account for only approximately 30% of current fossil fuel emis-
sions in this countury and even less worldwide.
The only feasible control option used a chemical solvent —
monoethanolamine (MEA) — to absorb CC>2 from smokestack emissions.
Alban.ese also compared three methods for disposing of captured
CC>2: conversion into a gas, liquid, or solid blocks, each of which
would be deposited into deep layers of the oceans.
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6-3
As shown in Table 6-1, the capital costs of an MEA control
system installed at a new 200-MW power plant were estimated to
be $46-$216 million (1980 $) for 50 percent removal efficiency
and $68-$290 million for 90 percent efficiency, depending on the
method of CC>2 disposal. These costs include the removal and
recovery systems (which capture CC^), and the significantly
more expensive facilities required to transport and dispose of
the captured CC>2.
They do not, however, include the costs of supplying energy
to operate the scrubbing and disposal systems. As Table 6-1 indi-
cates, the effective capacity of the power plant would drop by up
to one-third for 50 percent CO2 control and by up to roughly four-
fifths for 90 percent control. This reduction in capacity reflects
the energy penalty of the CC>2 scrubbing and disposal system.
Overall, the least expensive option for both 50 percent and
90 percent flue gas removal efficiency is gaseous disposal. (See
"Electricity Generation Costs" in Table 6-1.) Even for this
method of disposal, however, the cost increase is high enough to
seriously question the economic feasibility of controlling CC>2
using today's technologies. These increases would almost double
electricity costs for 50 percent removal and would increase costs
by a factor of four to achieve 90 percent efficiency.
As high as these costs are, they underestimate the real
costs for several reasons. As noted earlier, utilities contribute
only 30 percent of C02 emissions in the United States and an even
-------
TABLE 6-1
Costs of Generating Electricity With and Without G>> Control
for Initial Power Plant Capacity of 200-MW(e) (1980 dollars)
Net capacity, (D MW(e)
Capital investment (million $)
(a) Power plant (2)
(b) C02 control system*-3'
Total
Energy penalty for operating CC>2
Controls MW(e)
Total operating costs (4) (million $)
(a) Coal @ $30/ton
(b) O&M
(c) Barging costs (5,6)
(d) Capital charges @ 15% of
capital investment
Total
Electricity generation costs,
Mills/kWh (revenue requirements)
SC>2 removal with
no CO? control
200
160
160
18.9
4.8
24.0
47.7
30
SC>2 removed
Gaseous
disposal
161
160
152
312
39
18.9
5.8
46.8
71.5
56
+ 50% C02 <
Liquid
disposal
159
160
216
376
41
18.9
5.8
56.4
81.1
64
x>ntrol
Solid
disposal
134
160
46
206
66
18.9
7.2
5.0
30.9
62.0
58
SC>2 removed
Gaseous
disposal
86
160
194
354
114
18.9
5.8
53.1
77.8
113
+ 90% CO2
Liquid
disposal
83
160
290
450
117
18.9
5.8
67.5
92.2
139
control
Solid
disposal
37
160
68
228
163
18.9
7.2
5.0
34.2
65.3
221
(1) Electrical energy to drive the CO? control system is assumed to be obtained from the electrical output of the power
plant. Therefore: enet = ^ross^OO MWe) -
(2) Total capital investment @ $800/kW(e), including sulfur removal equipment.
(3) Total capital investment @ 1.2 times fixed capital investment.
(4) Based on 8,000 hours of operation per year.
(5) Dry-ice barging costs @ $15,000 per day. Costs for transporting dry ice from power plant to barge are not included.
(6) Barging costs are based on a 100-mile barging distance (500-meter disposal depth). For a 200-mile distance
(3000-meter disposal depth), barging costs are estimated at $9 million per year.
SOURCE: Albanese, Environmental Control Technology pg. 44.
-------
6-5
smaller percentage worldwide. Thus, the effectiveness of such
an approach is dubious. Moreover, the above analysis applies
only to control costs at new power plants located near large
bodies of water. Costs would be considerably higher to control
CC>2 emissions at other types of power plants and at industrial
sources. Thus, controlling CO2 emissions appears to be marginally
effective and prohibitively expensive.
SEQUESTERING CO? USING TREES
If the costs of installing and operating CO2 controls are
prohibitive, one potentially attractive alternative is to reduce
CC>2 after it has been emitted. By storing or sequestering the
carbon through tree growth, an existing sink of CC>2 would be
expanded.*
The first notion of using trees to reduce atmospheric C02
was developed in 1976 by the noted physicist Freeman Dyson.
Dyson simply set forth the technical parameters of using trees
to sequester CC>2r and concluded that "there seems to be no law
of physics or of ecology that would prevent us from taking action
to halt or reverse the growth of atmospheric CO2..." (Dyson, 1976).
* Some researchers have suggested that the trees should be cut
and pickled in a manner that prevents their decomposition
and the release of carbon to the atmosphere. Because of
other problems that must be overcome first, we have not
analyzed this aspect of the proposal.
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6-6
More recent analyses used Dyson's concepts as a starting point,
and examined in greater detail the feasibility of planting trees
on the scale required to absorb sufficient quantities of CC>2 to
limit or delay a global warming.
Sequestering CC>2 through forestation is attractive because it
offers a decentralized solution to a global problem. Many coun-
tries could contribute to a forestation effort. This is in direct
contrast to the energy options, which would fall most heavily on
those few countries with most of the world's fossil fuel resources.
Tree planting is also attractive in its own right as a means
of reversing past trends of deforestation. In many areas of the
world, the growth of forests will help reestablish the nutrients
in soil, prevent runoff, and stop the spread of deserts.
Despite the potential benefits of widespread forestation,
none of the earlier proponents of this idea now believes that it
is feasible (Greenberg, 1982). As illustrated below, the magni-
tude of the reforestation effort required appears to make this
approach untenable.
LAND REQUIREMENTS
Based on Dyson's original proposal, American sycamore seed-
lings would be planted on 6.7 million km2 of land (Greenberg, 1982)
Sycamore trees were selected because they grow well in temperate
climates with a minimum of rainfall.
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6-7
An enormous amount of land would be required to plant enough
trees to absorb substantial quantities of CC^. Sycamores would
absorb an average 750 tons of carbon annually for each square
kilometer until a steady state is reached when the forest matures
(after about 50 years). Thus, a total of 37,500 tons of carbon
would be sequestered for each square kilometer of sycamores. To
offset 50 years of CO2 emissions at the current annual rate
(approximately 5 billion gigatons per year of carbon from fossil
fuels), approximately 6.7 million km^ of sycamores would have
to be planted and maintained. The required acreage would be
roughly equal to the land area of Europe.
Identifying available land of this magnitude that is also
suitable for planting is a major problem. Thirty-eight percent
of the world's total land is already covered with trees. An
additional 9.5 percent is currently under cultivation and could
only be used to grow trees if food production were sacrificed
(MacDonald, 1982). Neither could be considered available for
the purposes of planting trees to be used to sequester CC^.
Much of the remaining land consists of desert, rock, sand, and
ice, and therefore would not be suitable for this endeavor.
FERTILIZER REQUIREMENTS
The enormous quantity of fertilizer that would be needed
to grow the sycamore plantations is a second critical barrier to
a successful sequestering plan. It would call for an estimated
17 million tons of nitrogen, 5 million tons of phosphorus (as
-------
6-8
P2O5), and 10 million tons of potassium (as potash, K2O). This
represents a very large percentage of the world's current ferti-
lizer production: approximately 30 percent for nitrogen, 40 per-
cent for potash, and 15 percent for phosphate (see Table 6-2).
TABLE 6-2
FERTILIZER REQUIREMENTS FOR GROWING AMERICAN SYCAMORE TREES,
COMPARED WITH WORLD FERTILIZER PRODUCTION JULY 1979-JUNE 1980
(in millions of metric tons)
Quantity of
Fertilizer World
Fertilizer Required Production
N 17 59.8
K2O 10 25.7
P2O5 5 32.3
Requirements as of %
of World Production
28.4%
38.9%
15.5%
Source: Minerals Yearbook, 1978-79.
Today's production figures do not clearly indicate the poten-
tial of the world's producers to raise output over time should
future demand increase substantially. This analysis requires a
closer examination of unused capacity and of the costs and avail-
ability of the inputs to produce each fertilizer.
Worldwide capacity to produce nitrogen fertilizer currently
stands at about 80 million metric tons (about 20 million tons
above current production). It is expected to increase to about
100 million tons by the end of the decade. Thus, there is enough
currently unused capacity to satisfy the needs of a sycamore
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6-9
plantation, and planned capacity expansion in the industry
suggests sufficient flexibility to respond to future increases
in demand. However, it is not at all clear that future increases
in capacity would be committed to growing sycamores. A significant
percentage would probably be diverted to increasing agricultural
productivity throughout the world.
World potash capacity also appears adequate to meet future
demands. Known reserves in the U.S.S.R, Canada, and New Mexico
would be sufficient to supply the K20 required for the sycamore
plantation, if necessary. Moreover, Canada alone expects to
nearly double its annual production between 1980 and 1990 from 11
million to 18 million tons (Harve, 1982), again demonstrating
flexibility to meet increases in demand.
The situation is less encouraging for phosphate requirements.
The United States and Morocco are the chief producers of phosphate
rock. At current rates of consumption, reserves seem adequate
only for the next 20 years. With a 15 percent increase in con-'
sumption resulting from the demands of the sycamore plantation,
known reserves would be exhausted several years sooner. Unless
new resources are located, scarcity could become a significant
problem (Minerals Yearbook, 1978-79).
COSTS OF SEQUESTERING
To further evaluate the viability of a CC>2 sequestering
program, resource requirements for supporting the program should
be translated into costs. Data on the costs of large-scale tree-
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6-10
planting programs are drawn from studies examining the feasibility
of creating tree farms to produce biomass for energy consumption.
One such study examined in detail the potential for growing
leucaenas on tree farms in Hawaii (Brewbaker, 1980). Although
leucaenas could grow well only in tropical climates throughout
the world, they are an attractive species for limiting increases
in CC>2 because they consume carbon at a higher rate (11.8 dry
weight tons of carbon per acre of wood) than American sycamores.
These trees could sequester 2,827 tons carbon/km2/year until the
forests matured. To sequester the same 50 years of carbon emis-
sions at the current annual rate, 1.77 million km2 of land would
have to be planted with leucaenas. This acreage is only 25 percent
of that required for the American sycamore, but would have to be
drawn from the more limited tropical areas of the globe.
Fertilizer requirements, shown with their percentage of world
production, are illustrated in Table 6-3. Because the leucaena
is a nitrogen-fixing legume, additional nitrogen fertilizer is
not necessary. But, it requires more than twice as much as the
sycamore of the fertilizer in the shortest supply — phosphate.
To grow at the optimal rate, leucaenas need about 60 inches
of rain a year. Hawaii gets about half that amount annually; the
remainder would have to be made up by irrigation. Assuming all
planted areas would have a climate similar to Hawaii, irrigation
equipment to move the required 365,190 billion gallons of water a
year would be required. Brewbaker estimated the cost of installing
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6-11
TABLE 6-3
FERTILIZER REQUIREMENTS FOR GIANT LEUCAENA,
COMPARED WITH U.S./CANADA AND WORLD PRODUCTION
FERTILIZER PRODUCTION
July 1978 - June 1979
(in millions of metric tons)
P205
K2O
CaCO3
Sulfur
Fertilizer
Requirements
for Leucaenas
11.9
8.7
1.0
0.7
World
Production
32.3
25.7
-
-
Require-
ments as a
% of World
Production
36.8
33.9
-
-
Source: Greenberg, 1982
a system to handle this amount of water to be $600/acre (1980 $)
for equipment, and $78.40/acre/year for water and services. The
total irrigation system for the entire plantation would require
a capital investment of §262 billion and annual operating expenses
of $34 billion.
The cost to purchase land is also substantial. On the
Hawaiian Island of Molakai, land costs are very high and not
representative of average global costs. They would run about
$3,000/acre to buy or $100/acre to lease, which results in a
one-time expense of $1,311 billion, or annual payments of $34
billion. Even if land prices were one-tenth these costs, or $300/
acre (lease payments of $10/acre), the costs would be $131 billion
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6-12
to buy or $4 billion a year to lease. Preparing the land after
purchase was estimated to cost another $55 per acre, or a total
of $25 billion (Brewbaker, 1980).*
Based only on land and irrigation costs, a total initial
cost of over $400 billion would be required. When added to the
costs for pesticides, fertilizers, nursery facilities, storage
and other requirements, a leucaena plantation would be exorbitantly
expensive.
Availability of land, total costs, and energy requirements
are not the only considerations in evaluating proposals to use
trees to sequester carbon. Any undertaking of this magnitude
will itself affect the world's climate. For example, by planting
trees on what is now fallow land, we will significantly alter
the earth's albedo (reflective characteristic) — more of the
sun's energy will be absorbed by the earth. Marchetti
estimates a 20 percent reduction in reflectivity (1978), thus
increasing the earth's temperature. The resulting temperature
rise would be roughly equivalent to the amount of CO2 emitted
during a seven-year period at current CC>2 emission rates
(Greenberg, 1982).
* This figure agrees with the $50/acre land preparation costs
estimated,in a similar study (Eraser, et al., 1976).
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6-13
In conclusion, rudimentary analysis of proposals found in
the literature and extrapolations from energy tree-farm work
show that sequestering atmospheric CC>2 by trees is an extremely
expensive, essentially infeasible option for controlling CO2-
OFFSETTING THE GREENHOUSE WARMING
In contrast to actions that control or capture CC>2 emis-
sions, an alternative proposal is directed at reducing the amount
of solar radiation that penetrates the troposphere.* Under this
proposal, large quantities of sulfur dioxide injected into the
stratophere would reduce solar radiance about 2 percent by
absorbing incoming visible sunlight. This reduction in incoming
radiation would roughly neutralize the warming created by a CC>2
doubling.
Depositing the required 35 million tons/year of SC>2 in the
stratosphere would require 750-800 daily airplane flights. To-
gether with the costs of the sulfur dioxide, total costs would
be roughly $21 billion/year (Broecker, 1983).
Costs aside, the practicality of such a scheme depends pri-
marily on the associated environmental effects. Adding sizable
quantities of SC>2 to the stratosphere may affect many chemical
* This proposal was first suggested by Budyko (1974). A recent
paper by Broecker (1983) provides a preliminary analysis of
the costs and environmental implications of this approach to
counteracting a greenhouse warming.
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6-14
reactions in the stratosphere, including those that control the
concentrations of ozone and ^0.* Changes in these gases could
significantly contribute to a warming. It could also increase
acid rainfall in the troposphere. Much more analysis of each of
these effects is required before the feasibility of this proposal
can be judged.
SUMMARY
Current proposals to slow a greenhouse warming by nonenergy
means generally do not appear effective or feasible. At best,
they require additional analyses before even tentative conclusions
can be reached. Nonetheless, they retain their appeal if for
no other reason than energy options appear to be economically
and politically unacceptable.
Of the three proposals reviewed in this chapter, the seques-
tering may hold some promise, but only if new biological organisms
can be developed. Such organisms would have to be capable of
absorbing large quantities of CC>2 at low cost, and without adver-
sely effecting fragile ecosystems. Until such time, however,
sequestering cannot be viewed as a feasible solution.
Injecting SC>2 into the atmosphere is an intriging proposal,
but raises questions about costs and adverse environmental effects.
Much more research is needed.
* Broecker projects a 2.5 fold increase in atmospheric N20, which
is also a greenhouse gas.
-------
CHAPTER 7
CONCLUSIONS
Based on the evidence marshalled to date, some warming of
the lower atmosphere over the next century from increasing levels
of C02 and other greenhouse gases seems inevitable. The only
questions remaining are how large the temperature rise will be
and how fast it will occur. These questions are critical. The
consequences of a greenhouse warming and related societal re-
sponses will depend strongly on both the size and the speed of
temperature rise.
EFFECTIVENESS OF POLICIES AND SENSITIVITY OF RESULTS
The timing of a projected 2°C rise in temperature is the
primary yardstick used to judge the effectiveness of alternative
policies aimed at delaying a greenhouse warming. The magnitude
of global warming in 2100 is a secondary measure. In addition to
policy effectiveness, we extensively explored the sensitivity of
temperature estimates to current scientific uncertainties.
In the Mid-range Baseline, a 2°C warming is reached in 2040.
Figure 7-1 compares this case with the results for alternative
baseline, sensitivity, and policy scenarios. The main conclusions
are:
• The future mix of fuel use has almost no effect on the
date of a 2°C warming. Neither reductions in energy
use (e.g., increased conservation) nor increases in the
use of fossil fuels would appreciably change the timing
of a 2°C rise.
-------
FIGURE 7-1
CHANGES IN THE DATE OF A 2° C WARMING
(PROJECTED DATE IN MID-RANGE BASELINE: 2040)
ALTERNATIVE ENERGY
BASELINES
2070
(MID-RANGE CASE) 2040*
2025
5 YRS 5 YRS
HIGH
GROWTH
TEMPERATURE
SENSITIVITY t
25 YRS
HIGH HIGH LOW NO
FOSSIL ELECTRIC DEMAND GROWTH
HIGH
5 YRS
LOW
ENERGY POLICIES
25 YRS
15 YRS
5 YRS < 5 YRS
to
10 YRS
15 YRS
BAN ON
SHALE
AND
SYN-
FUELS
BAN ON
COAL
BAN ON
COAL
AND
SHALE
300% 100%
WORLD WORLD
FOSSIL FOSSIL
FUEL FUEL
TAX TAX
•REFERS TO GREENHOUSE GASES OTHER THAN CO2: NITROUS OXIDE, METHANE, AND CHLOROFLUOROCARBONS.
tREFERS TO THE TEMPERATURE RISE IN RESPONSE TO A GIVEN INCREASE IN GREENHOUSE GASES
ONCE AN EQUILIBRIUM HAS BEEN REACHED.
-------
7-3
• Of the energy policy options analyzed, a ban on coal
instituted in 2000 would effectively delay a 2°C
warming by 15 years. Bans on both coal and shale oil
would result in a 25-year delay. Taxes on all fossil
fuels, or bans on individual fuels other than coal pro-
duce only minor delays and are not considered effective.
For example, a 300% U.S. tax on fossil fuels would have
almost no effect on shifting the date of a 2°C warming;
a worldwide tax at this level would only delay the warming
by about 5 years. Similarly, a 100% tax applied worldwide
would delay the date of a 2°C rise by less than 5 years.
• Different assumptions about other greenhouse gases and
the actual temperature sensitivity of the atmosphere to
increases in CC>2 are by far the most significant factors
in projecting the timing of a 2°C rise. Assuming green-
house gases (other than CC>2) remain at constant levels
delays the projected date of a 2°C warming by 30 years.
If these gases increase at a much higher rate than in
the Mid-range Baseline, a 2°C warming might occur as soon
as 2025. Using the probable range of values for the
temperature sensitivity of the atmosphere (from 1.5°C to
4.5°C) delays the target date 25 years or advances it 10
years (respectively).
A similar comparison of results using the projected tempera-
ture in 2100 also proves insightful, although less confidence can
be placed in these very long-term projections. The estimated
temperature in the Mid-range Baseline is 5°C. Figure 7-2 summarizes
results for other baselines, changed assumptions, and energy policy
scenarios.
Several useful, albeit tentative, conclusions can be drawn:
• Alternative assumptions about future energy patterns
contribute negligibly to variations in projected
temperature in 2100.
• Policy options that involve bans on fossil fuels could
significantly reduce the warming by 2100. A ban on coal
would reduce the temperature rise in 2100 from 5°C to
3.4°C; when coupled with a ban on shale oil, the total
projected warming would be cut in half (to 2.5°C).
-------
FIGURE 7-2
CHANGES IN TEMPERATURE PROJECTED FOR 2100
(PROJECTED MID-RANGE BASELINE TEMPERATURE: 5° C)
8° Cr
(MID-RANGE CASE) 5° C
2° CL.
ALTERNATIVE ENERGY
BASELINES
+0.30 HIGH LOW
ELECTRIC DEMAND
NO
GROWTH
HIGH
FOSSIL -°-6°
-0.7°
TEMPERATURE
SENSITIVITY*
+1.2°
LOW
HIGH
GROWTH
-1.6°
ENERGY POLICIES
100% 100%
BAN ON WORLD U.S.
COAL FOSSIL FOSSIL
BAN ON BAN ON AND FUEL FUEL
SHALE COAL SHALE TAX TAX
HIGH
-0.6°
-1.6°
I I
-0.7°
-2.5°
-2.9°
-0.2°
•REFERS TO GREENHOUSE GASES OTHER THAN CO2; NITROUS OXIDE, METHANE, AND CHLOROFLUOROCARBONS.
tREFERS TO THE TEMPERATURE RISE IN RESPONSE TO A GIVEN INCREASE IN GREENHOUSE GASES
ONCE AN EQUILIBRIUM HAS BEEN REACHED.
-------
7-5
• Neither a U.S. nor a worldwide tax on fossil fuels
(even a tax of 300%) would be as effective as selected
fuel bans.
• Uncertainties regarding the growth in greenhouse gases
other than CC>2 and the temperature sensitivity of the
atmosphere are major sources of variability in projected
temperature.
FEASIBILITY OF POLICY OPTIONS
Though a ban on coal (or coal and shale oil) is the only
policy that could significantly delay a 2°C warming, it appears
to be economically and politically infeasible. This is due to
(1) the substantial costs of these policies, (2) the unequal
distribution of costs and benefits across nations, and (3) the
need for worldwide cooperation to ensure their effectiveness.
We also found other efforts to reduce CO2 levels to be
infeasible, at least at present. Scrubbing C02 emissions has
limited applicability — it only applies to large power plants
— and is prohibitively expensive. Forestation, on the scale
required to absorb significant amounts of CO2f would cause severe
competition for available land, fertilizer, and irrigation.
Injecting SO2 into the stratosphere to increase reflection of
incoming solar energy appears somewhat more practical (although
still expensive), but major uncertainties regarding environmental
side effects remain to be investigated.
-------
7-6
MODELING ASSUMPTIONS
We made numerous assumptions and approximations, which
moderate the strength of our conclusions. The most important
assumptions are:
• Worldwide population is assumed to reach zero growth
levels by 2075.
• The projections of future fuel-use patterns assume
that no exotic energy technologies (e.g., nuclear
fusion, solar production of hydrogen, "energy plants")
would be commercially available within the 120-year
time frame of this study.
• Possible reductions in energy demand due to lower
heating requirements as the earth warms were assumed
negligible.
• The heat diffusivity of the ocean was set at 1.18
cm^/sec, and the effects of volcanic activity and
variations in solar luminosity were assumed to follow
historical patterns.
No attempt was made to evaluate the significance of these assump-
tions in quantitative terms. In our opinion, however, the assump-
tions are reasonable "educated guesses".
Two other key assumptions were subjected to a limited sensi-
tivity analysis. These are the rate of economic growth in the
less developed and developing countries after 2050, and the income
(or GNP) elasticity of energy demand. In both cases, changing
the value of these paramenters within reasonable ranges produced
only minor changes in projected temperature.
-------
7-7
IMPLICATIONS OF FINDINGS
Our findings support the conclusion that a global greenhouse
warming is neither trivial nor just a long-term problem. They
•also- underscore the large degree of uncertainty embedded in the
temperature projections. Taken together, these characteristics
of our results point to the need for additional research aimed
at reducing the range of uncertainty in temperature projections.
Specific research needs should focus on (1) how atmospheric
temperature responds to changes in greenhouse gases (i.e.,
narrowing the range of the temperature sensitivity parameter, Te),
-and (2) the sources, fate, and effects of greenhouse gases other
than CC>2 (specifically, nitrous oxide, methane, CCl2^2 and CC^F).
But even with better knowledge of the magnitude and pace of
global warming, we will still be faced with the challenge of
developing appropriate responses. Innovative thinking and
strategy-building are sorely needed. Means must be found to
explore the advantages of climate change where they appear, and
to minimize the adverse effects.
Finally, our findings call for an expeditious response.
A 2°C increase in temperature by (or perhaps well before) the
middle of the next century leaves us only a few decades to plan
for and cope with a change in habitability in many geographic
regions. Changes by the end of the 21st century could be cata-
strophic taken in the context of today's world. A soberness
and sense of urgency should underlie our response to a greenhouse
warming.
-------
APPENDIX A
ENERGY SUPPLY OPTIONS
The mix of fuels employed to satisfy energy demands varies
considerably among geographic regions and is likely to shift
substantially over the next several decades. Table A-l is a
compilation of energy production by fuel type in 1979 for the
United States, the developed and developing market economy
countries, the centrally planned countries, and the world. As
shown, all nations are heavily dependent on fossil fuels; solids
(mainly coal) are the primary fuels produced in all developed
countries, while liquids predominate in the developing countries.
This reflects both the domestic demand for these fuels and the
relative abundance in each country. Electricity is primarily
important in the developed part of the world, with nuclear power
important only in the countries with developed market economies.
Not identified separately in this table are gases and liquids
made from biomass and coal, use of biomass as a solid fuel, passive
solar applications, and decentralized use of active solar systems.
Biomass is a large source of energy in many developing countries,
while all forms of active and passive solar systems are growing
in popularity in the developed nations. In addition, a variety
of new fuel sources and energy production technologies have
appeared on the horizon. Key characteristics of both traditional
-------
A-2
TABLE A-l
WORLDWIDE ENERGY PRODUCTION IN 1979
Primary Energy Production (EJ)£/
Region
U.S.
Solids
17.8
Developed Market 32.7
Economies
Developing Market 3.6
Economies
Centrally Planned 44.0
Economies
World
80.2
Liquids Gases
20.4 21.1
29.9 32.0
77.1 5.0
30.5 16.9
137.5 54.0
Electricity (GWh)
Nuclear Other Total
0.3
0.5
0
0.1
0.6
2.0
4.7
0.8
1.9
7.4
2.3
5.2
0.8
2.0
8.0
Total
61.2
100.5
87.0
92.7
280.2
a/ Production for all fuels except electricity is in units of primary energy; for electricity,
~ production is in units of final energy.
Source: United Nations, Dept. of International Ecnomic and Social Affairs,
(1981), Yearbook of World Energy Statistics, 1979, U.N., New York,
N.Y.
-------
A-3
and emerging fuel sources, and their likely utilization into the
next century are discussed below.*
CURRENT AND FORESEEABLE ENERGY SOURCES
Table A-2 summarizes the current estimates of energy sources
which are likely to predominate throughout the next century. As
indicated, it appears that conventional sources of oil and gas
will continue to fuel world economies at least until the turn of
the century, and that coal will gain an increasing share of the
market throughout the next century. The high demand for liquid
and gaseous fuels is likely to continue, due to their high energy
content, transportability, storability, and utilization in end
use technologies. As conventional supplies of oil and gas become
increasingly expensive, unconventional oil and gas supplies and
synthetic fuels from biomass and coal become economically more
attractive. Use of non-fossil energy sources will also grow.
Nuclear and solar fuels should gain a larger share of the electric
market, although expansion of nuclear power on a sustainable basis
depends on development of breeder technology. Solar applications
in the residential and commercial sectors will continue to grow.
The degree to which these trends materialize will depend in part,
on continued reduction in the cost of shale oil, synthetic fuel,
and solar options.
* For more information on energy supplies, see, for example,
Anderer, et al, 1981. Much of the information presented
here is taken from this source.
-------
A-4
TABLE A-2
SUVIMARY OF ENERGY SUPPLIES
Energy Category
Conventional Gas
Unconventional Gas
Conventional Oil
Unconventional Oil
Coal (Solid)
Bicmass (Solid)
Specified Fuel Types
Gas recoverable with
traditional procedures
Gas in geopressure zones
and tight formations
Oil recoverable with
traditional procedures
Heavy oil needing
enhanced recovery, tar
sand oil, shale oil
Coal used as a solid
fuel
Bionass from energy
farms and wastes, used
as solid fuel
Location of Major Deposits
Middle East, Africa, Eastern
Europe, USSR, North America
Same as conventional gas
resources
Middle East, Africa, North
America, Western Europe,
USSR
Broadly distributed with
2/3 of shale oil in North
America
U.S., China, USSR
Widely distributed
Supply Levels
About 9,500 EJ
Perhaps 9,000-
31,000 EJ
About 12,500 EJ
About 12,500 EJ
of heavy and tar
sand oil, and
about 16,000 EJ
of shale oil
About 95,000 EJ
About 160 EJ/yr
fron crops and
perhaps 30 EJ/yr
from waste
Comments
Production
should peak
after 2000
More explo-
ration is
needed to
map these
deposits
Production
should peak
before 2000
Production
costs are
considerably
higher than
for conven-
tional oil
Availability
of land,
conpetition
with food
uses, and
production
costs limit
its use
-------
A-5
TABLE A-2 (Continued)
Energy Category
Synthetic Fuels
Specified Fuel Types
Liquids and gases frcm
coal and biotiass
Location of Major Deposits
See Coal and Bionass
Solar
Res idential/conmercial
applications (passive
and active), centralized
solar electric
Dependent on the amount of
solar radiation
Nuclear
Uranium ore
Supply Levels
See Coal and
Bionass
Availability
of land does
not appear to
be limiting
(10 million km2
may be available)
Comnents
Availability
is related
to produc-
tion costs.
Coal-derived
synfuels
appear less
costly than
biomass syn-
fuels
Res./com.
applications
are wide-
spread, high
capital
costs limit
solar-
electric
Africa, Southeast Asia, North
America, USSR, E. Europe, Latin
America
Depends on nuclear
technology (fission
vs. breeder)
a/ Expressed in energy equivalents of primary energy, where appropriate.
SOURCE: Anderer, J. et al., (1981), Energy in a Finite World, IIASA, Ballinger Publishing Co., Cambridge, Mass.
-------
A-6
EXOTIC AND HYBRID FUEL SYSTEMS
The farther into the future projections extend, the more
likely that totally new energy forms will come into play.
Following are currently exotic energy sources, some of which may
become commercially significant before the end of the 21st century,
• Nuclear Fusion — Fusion involves the extraction of
"heavy" hydrogen (deuterium) from water and the combi-
nation of two hydrogen atoms to form helium. Although
it has long been hailed as the path to unlimited energy,
scientific feasibility has yet to be established. Demon-
strations of technological feasibility must then follow,
with mastery of materials development and system
engineering looming as major hurdles.
• Hydrogen — Hydrogen may become the "energy carrier of
the future." Most schemes for generating hydrogen are
based on splitting water using solar energy directly
(thermolysis or photolysis) or indirectly via electricity
(electrolysis). Hydrogen would then be used as a substi-
tute for natural gas. Although the technical feasibility
of water splitting on a large scale has yet to be estab-
lished, a "hydrogen economy" remains at least a distant
possibility.
-------
A-7
• Solar Satellites — Collecting solar energy in space
and transmitting it to earth via microwave is another
long-range possibility. Due to the large size of the
required collector, current launch and deployment costs
render this scheme economically infeasible. However,
future advances in space equipment may change this
assessment.
• Energy Plants — Rapid improvements in bioengineering
may provide the basis for improving the efficency or
redirecting the end products of photosynthetic processes
to produce commercial fuels such as hydrogen. At this
time, scientific feasibility of developing "super species'
remains to be established.
• Combinations — Concepts for combining end uses and
supply generation facilities to better utilize waste
heat already are being employed. These include co-
generation of steam and electricity and district
heating. Future combination may include the use of
nuclear energy to generate heat for coal gasification
and liquifaction. The requisite hydrogen for synfuel
production may be provided by splitting water with
solar energy. Other hybrid systems may emerge as the
component parts become practical.
-------
A-8
ENVIRONMENTAL AND SAFETY CONSTRAINTS
Certain supply options are likely to be constrained by nega-
tive environmental effects (other than C02 emissions). Nuclear
power, for example, is currently facing a severe handicap due to
(1) the lack (as yet) of politically acceptable means of waste
disposal, and (2) concern over reactor safety and nuclear fuel
theft.* The growth of the nuclear industry hinges in large part
on overcoming public fears, as well as on solving the purely
technical issues involved in waste disposal, reactor safety, and
fuel security. Other sources of energy (1) are more environ-
mentally benign (e.g., solar), (2) are subject to technically
feasible (but perhaps costly) environmental controls (e.g., high
sulfur coal), or (3) create less visible problems (e.g.; safety
for oil rig workers). Environmental problems resulting from
extensive use of future energy sources such as shale oil and
synthetic fuels have yet to be completely understood. If major
problems emerge, development could be delayed. At a minimum,
the costs of mitigating these problems will make the affected
fuels less economically attractive.
* These problems have stymied the nuclear industry in the U.S.
No new reactors have been ordered by utility companies since
1978 while 60 previously planned facilities have been can-
celled over this 5-year time period. On the other hand,
nuclear generating capacity has continued to grow in other
countries. For example, total capacity expanded from about
50 to 70 gigawatts in all free world countries other than the
United States (U.S. Dept. of Energy, 1981).
-------
APPENDIX B
THE TEA ENERGY AND CO? EMISSION MODEL
The IEA/ORAU,* energy and C02 emission model was developed
by Jae Edmonds and John Reilly at the Institute for Energy Analysis
as an assessment tool for policy analysis. It provides a consis-
tent representation of economic, demographic, technical, and policy
factors as they affect energy use and production, and CC>2 emissions.
The general structure and key analytical features of the model are
described in the text. This discussion provides a more detailed
description of the structure, data base, output, and usage of the
model, all of which are extensively documented elsewhere.**
ENERGY DEMAND
Energy demand for each of the six major fuel categories is
developed for each of the nine regions separately. Five major
exogenous inputs determine energy demand: population, economic
activity, technological change, energy prices, and energy taxes
and tariffs.
* The Institute for Energy Analysis is part of the Oak Ridge
Associated Universities.
** See the following volumes: Edmonds, Reilly, and Dougher (1981)
and Reilly, Dougher, and Edmonds (1981).
-------
B-2
An estimate of GNP for each region is used as a proxy for
both the overall level of economic activity and as an index of
income. While the level of GNP is an input to the system, it is
derived from demographic projections of the labor age population
and an assessment of likely labor force participation rates and
levels of labor productivity. These estimates were generated
in conjunction with Nathan Keyfitz of Harvard University and
Philander Claxton of the World Population Society.
Improvements in energy technology beyond those induced by
real price increases or income decreases is reflected in a para-
meter called "enhanced energy efficiency". In the past, tech-
nological- progress has had an important influence on energy use
in the manufacturing sector of advanced economies. The inclusion
of an energy technology parameter allows scenarios to be developed
which incorporate either continued improvements or technological
stagnation as an integral part of scenarios.
The final energy factor influencing demand is energy price.
Each region has a unique set of energy prices which are derived
from world prices (determined in the energy balance component of
the model),transportation costs, and region-specific taxes and
tariffs. The model can be modified to accommodate non-trading
regions for any fuel or set of fuels. It is assumed that no
trade is carried on between regions in solar, nuclear, or hydro-
electirc power, but all regions trade other types of fuels.
-------
B-3
The four secondary fuels (refined oil, refined gas, refined
solids [coal and biomass], and electricity) are consumed to pro-
duce energy services. In the three OECD regions (Regions 1, 2,
and 3 in Figure 3-2), energy is consumed by three end-use sectors:
residential/commercial, industrial, and transport. In the remaining
regions, final energy is consumed by a single aggregate sector.
The demand for energy services in each region's end-use
sector(s) is determined by tne cost of providing these services,
and the levels of income and population. The mix of secondary
fuels used to provide these services is determined by the relative
costs of providing the services using each alternative fuel. A
log it share function is employed to calculate these shares.
The price of secondary fossil fuels is a function of the
regional price of primary fuels and the cost of refining:
Pjr = pir<9ij) + nj
Pir = (Pi + TRir) TXir
Where: Pjr is the price of secondary fuel j in region r;
P£r is the price of primary fuel i in region r;
gij is the efficiency of refining i into j; hj is
the non-energy cost of refining; P^ is the world
market price of fuel i; TRir is the cost of
transporting fuel i to region r, and TXir is the tax
on fuel i in region r.
The price of electric power is estimated as a weighted sum of
the prices of the alternative electricity-generating fuels, and
the cost of energy conversion. Likewise, the price of synthetic
oil and gas from coal and biomass are functions of the price of
coal (biomass) and the cost of liquification or gasification.
-------
B-4
Prices calculated in this general manner serve as key inputs
to the demand estimation process. Total regional demand for
secondary energy services is calculated as a function of aggregate
energy price, income level, and population (or level of economic
activity -- GNP) in each region; price and income elasticities
modulate the effect of the price and income values, respectively.
Demand is then allocated among secondary fuels using (1) historic
market shares and (2) the relative cost of providing energy services
from each fuel within, as noted above, a logit share formulation.
For fuels which are not traded internationally (i.e., nuclear-,
solar-, and hydro-electric), demands and supplies calculated this
way are, by identity, equal. For the other fuels, however, a
market-clearing mechanism is simulated in which prices for gas,
liquids, and solids are altered in order to balance supplies and
demands. This is described in the Energy Balance section.
ENERGY SUPPLY
Three generic types of energy supply categories are distin-
guished: resource-constrained conventional energy, resource-
constrained renewable energy, and unconstrained energy resources.
There are eight different supply modes across these categories as
shown in Chapter 3. Production of conventional gas and oil are
represented by a logistics curve which reflects historic supply
levels and estimates of remaining deposits:
F(fc) = exp(a + bt)
l-F(t)
-------
B-5
Where: F(t) is the cumulative fraction of the total resource
exported by time t, and a and b are empirical parameters.
Production rates of these fuels are thus insensitive to price
levels.
Production levels of unconventional oil and gas, nuclear,
solar, and solids (coal and biomass) are modeled as "backstop
technologies". That is, a base level of production is assumed
over time if real prices remain constant. Shorter term supply
schedules are then super-imposed on these long-term trends to
reflect the increase or decrease in production due to price rises
or declines. If the price falls below a breakthrough price level,
then production ceases. These relationships are encompassed in
the following general expression:
P = a [exp(g/b)c]
Where: P is the price of the backstop fuel; a is the break-
through price; b is a parameter which determines the
"normal" backstop price; c is a price elasticity con-
trol parameter; g is the ratio of output in year t to
the base level output associated with the backstop price.
Production schedules of synthetic oil and gas are determined
by the price (supply schedules) of solids, the cost of producing
the synthetic fuel, and associated non-energy costs. The share
of coal or biomass allocated to the production of synfuels is
specified by a logit share equation, with the relative cost of
synfuels versus other sources of gas and oil and the price elas-
ticity of production as key terms.
-------
B-6
Resource-constrained renewable fuels are considered constant-
flow sources. That is, the rates of energy production are limited
by the availability of the resource.
ENERGY BALANCE
The supply and demand modules each generate energy supply
and demand estimates based on exogenous input assumptions and
energy prices. If energy supply and demand match when summed
across all trading regions in each group for each fuel, then the
global energy system balances. Such a result is unlikely at any
arbitrary set of initial energy prices. The energy balance com-
ponent of the model is a set of rules for choosing energy prices
which, on successive attempts, brings supply and demand nearer a
system-wide balance. Successive energy price vectors are chosen
until energy markets balance within a pre-specified bound.
CO? RELEASE
Given the solution from the energy balance component of the
model, the calculation of CC>2 emissions rates is conceptually
straightforward. The problem merely requires the application of
appropriate carbon coefficients (carbon release per unit of
energy) at the points in the energy flow where carbon is released.
Carbon release is associated with the consumption of oil, gas,
and coal. Large amounts of CC>2 are released from the production
of shale oil from carbonate rock and from the production of
synthetic fuels from coal. A zero carbon release coefficient
-------
B-7
is assigned to bioraass, nuclear, hydro, and solar. The specific
coefficients used in the modelling analysis and listed in Chapter
3 were compiled by IEA from various sources, and conform to the
IEA fuel accounting conventions as shown in Figure B-l.
-------
B-8
FIGURE B-l
APPLICATION OF CO2 EMISSION COEFFICIENTS
IN THE IEA MODEL
Primary
Energy
Secondary
Energy
Repressing Flarin8
Coal
"'S
-*.
-------
APPENDIX C
THE ORNL CARBON CYCLE MODEL
The Oak Ridge National Laboratory carbon cycle model repre-
sents flows and stocks of carbon on a global scale. Terrestrial
carbon is modeled in considerable detail while ocean carbon is
represented by a simple box-diffusion concept. A general over-
view of the model is presented here.*
Figure C-l depicts the overall structure of the model.
Carbon in living material is divided between ground vegetation
and trees, and, within trees, between "woody" and "nonwoody"
parts. Dead organic matter is divided between detritus/decomposer
and active soil carbon. Finally, carbon in the ocean is subdivided
into surface (260m) and deep layers.
For each of the carbon reservoirs, equations specify maximum
stocks of carbon and rates of flow into and out of the reservoirs.
In general, terrestrial flows are modeled as linearly dependent
on carbon content of the ith donor reservoir (F^j = a^j C^) or as
a more complicated logistics function.
The logistic functions for trees includes a term for carbon
release to the atmosphere from forest clearing. Permanent forest
clearing is reflected by reductions in the parameters governing
storage capacity. Where clearing is temporary, reestablishment
of forests occurs in a delayed exponential fashion. (The forest
clearing option was not activated for this study).
* For a more detailed discussion see Emanuel, et al. (1981).
-------
C-2
FIGURE C-l
STRUCTURE OF THE ORNL GLOBAL CARBON CYCLE MODEL
ATMOSPHERE
I
GROUND
VEGETATION
NONWOODY PARTS
TREES
WOODY PARTS
TREES
DETRITUS/
DECOMPOSERS
ACTIVE SOIL
CARBON
SURFACE OCEAN
I
DEEP OCEAN
THIS FIGURE IS TAKEN FROM AN UPDATED MANUSCRIPT BY W.R.
EMANUEL AND OTHER AT OAK RIDGE NATIONAL LABORATORY.
-------
C-3
Net uptake of carbon by the ocean is limited by the avail-
ability of carbonate ion. The rate at which gaseous CC>2 is dis-
solved in seawater depends on the rate of reaction with CO3,
which is the first step of a process by which CC>2 is incorporated
into various seawater carbonate compounds.
Most,flux equations are temperature-sensitive. Sensitivity
to temperature is significant as a rise in temperature is the
most direct consequence of an increase in atmospheric C02» The
original version of the ORNL represented this temperature-CC>2
relationship by a simple exponential equation rather than through
a series of heat-flux equations. This aspect of model was ignored
in favor of the relatively sophisticated heat flux relationships
in the GISS model. These relationships were utilized by coupling
the two models (see the Appendix E).
The model inputs are estimates of fossil fuel carbon emis-
sions on a yearly or longer time period basis from 1980 until
some future year. (The IEA model outputs are on a 25-year basis.
Estimates were provided on a 5-year basis by interpolating between
the 25-year estimates). Outputs are atmospheric CC>2 for 5-year
time intervals.
The model simulates historical patterns of carbon cycling
from 1740 to 1980 on an annual basis. The resulting time trend
in CO2 was modified slightly so that the concentration in 1980
was 339 ppm. This corresponds to the level estimated by the GISS
model in 1980 given estimates of fossil fuel carbon emissions in
-------
C-4
1975 (the starting point of the IEA model) used in this study,
and matches observed CC>2 levels for 1980. The model was then
run to produce estimates of atmospheric CC>2 from 1980 to 2100.
-------
APPENDIX D
THE GISS ATMOSPHERIC TEMPERATURE MODEL
The GISS model used in this study is based on a one-dimensional
(1-D) radiative-convective (RC) model for estimating temperature
increases associated with atmospheric C02 rises.* The 1-D, RC
model computes vertical temperature profiles over time from net
radiative and convective energy fluxes. Radiative fluxes, in
turn, depend on changes in atmospheric gases, especially C02- The
GISS model is an empirical representation of the 1-D, RC model, as
modified by Hansen and co-workers to include terms for greenhouse
gases other than C02.
HEAT FLUX COMPUTATIONS
The heat flux into the earth's surface is estimated by an
equation which contains all key temperature-related terms:
F(t) = 2.6x10-5(AC02) _ - 5.88x10-3 (AT) + 3.68.5x10-4 (AT) 2
[1 + .0022( C02)]°-6 ~T^V
- 4.172x10-7 (AC02) (AT) + 1.197xlQ-3 (ACH4)0-5
-Te—
+ 5.88x10-3 (AN20)0-6 + 3.15x10-4 (ACC3) + 3.78x10-4 (ACC2)
- 1.197x10-4 (ACH4)(AN20) + 2.40xlO'2 (AV) + 2.10x10-3 (AV)2
- 1.17X10-3 (AT)(AV) + 3.184x10-1 (AS)
* See Hansen, et al. (1981 ).
-------
D-2
Where: F(t) is the heat flux as a function of time in cal/min-cm2,
AC02 is the change in atmospheric C02 from the 1880 value
(293 ppm) in ppm.
AT is the change in atmospheric temperature (surface level)
from the 1880 value in °C
ACH4 is the change in atmospheric CH4 from the 1880 value
(1.6 ppm) i n ppm.
AN20 is the change in atmospheric N20 from the 1880 value
(0.300 ppm) in ppm.
ACC3 is the change in CClaF from the 1880 value (0 ppb)
in ppb.
ACC2 is the change in CC12F2 from the 1880 value (0 ppb)
in ppb.
AV is the change in atmospheric optical depth from a base-
line level due to volcanic activity in dimensionless units.
AS is the change in solar luminosity from a baseline
level in fractional units.
Te is the equilibrium temperature—the assumed temperature
rise when C02 doubles from the 1880 level (from 293 to
586 ppm).
The heat flux is estimated from time periods ranging from
each month to each year (a semi-monthly time step was used in this
study). The appropri ate AT value for calculating F(t) in each
time period (t=n) is the value estimated for the previous period
(t=n-l). For a simple one-layer ocean model, T is obtained by
solving the following differential equation:
dAT = F(t.)
~~dT ~t^~
Where: C0 is the heat capacity of the mixed layer of the ocean
per unit area (cal/cm2).
Estimates of heat flux from the empirical equation described
above were compared by Lacis with the RC model calculations. The
two estimates agreed to within one percent for C02 values of 0 -
1220 ppm, and to within 5 percent for C02 values of 1220-1700 ppm
(Lacis, et al., 1981).
-------
D-3
Values for the parameters in the empirical heat flux equation
were summarized in Table 3-4 and are detailed below:
AC02: value obtained from the IEA and ORNL models
ACH4: 1.6 ppm through 1980, increased by 2%
per year thereafter (Recent measurements
of methane suggest a worldwide average
of roughly 1.6 ppm. Concentrations are
believed to have increased from between
0.5% and 3.0% over the last decade; levels
are assumed constant before 1980 as a
simpli fi cation).
AN20: 0.300 ppm through 1980, increased at 0.2%
per year thereafter (This is the best
estimate for 1980, with levels believed
to have changed only slightly over time.)
ACC2 and ACC3: 0 before 1980, increased as shown thereafter:
Year ACC2 ACC3
1980
1990
2000
201 0
2020
2030
2040
2050
2060
2070
2080
2090
2100
0.306 ppb
0.469
0.616
0.749
0.870
0.979
1.080
1.166
1.247
1.320
1.386
1.446
1.500
0.176 ppb
0. 269
0. 345
0.407
0.458
0.500
0.534
0.562
0. 585
0.604
0.619
0.632
0.642
-------
D-4
(Levels of chlorofluorocarbons began to increase from
zero in the 1940s, with a rapid rise in the 1970s.
The 1980 estimates are based on recent measurements.
Assuming an immediate increase from zero to current
levels in 1980 introduces some error in temperature
estimates between 1950 and 1980, but does not influence
future estimates.)
AV: constant 0.007 each year from 1880 - 2100
AS: 0 from 1880 - 2100
Te: 1.5°C, 3.0°C, and 4.5°C
DIFFUSION OF HEAT IN THE OCEAN
The ocean model consists of a mixed layer of depth Hm = 100m
and a thermocline with 63 layers and a total depth H = 900m. The
mixed layer temperature is assumed to be independent of depth,
while the thermocline temperature is defined by a diffusion equa-
tion with constant thermal diffusivity. The layering is diff-
erent from that used in the ORNL model, but the difference is not
important.
The temperature in the mixed layer (ATm) is a solution of
the equation:
= F(t) + FD(t)
where C is the heat capacity of water, F(t) is the heat flux from
the atmosphere into the ocean and
'"<*>• -^H1 z = Hm;
is the heat flux from the thermocline into the mixed layer.
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D-5
Note that the z-axis is directed toward the bottom of the ocean.
Also, since all values are in units of g, cm, sec, and cal; heat
conductivity x is numerically equal to heat diffusivity K. The
value for diffusivity was set at 1.18 cm2/sec.
The temperature change in the thermocline (AT) is determined
by the diffusion equation:
2
C 9 AT(z,t) = K 8AT(z,t)
8 t 8 zz
The boundary conditions for AT are:
AT - ATm at z = Hm
and zero heat flux at the bottom of the thermocline:
K 8 AT = 0 at z = H .
9 Z
Thus it is assumed that no energy escapes through the lower
boundary of the thermocline. Note that ATm and AT are temperature
changes of the mixed layer and the thermocline between the initial
time (1880) and time t. It is assumed that in the year 1880 ATm
= AT = 0, and thus that the ocean temperture was in a state of
equilibrium with the atmosphere at that time.
Required input data are atmospheric C02 levels on a yearly
or longer time period basis. Five-year estimates were obtained
from the ORNL, or alternatively, were obtained by multiplying a
specified retention ratio times the interpolated 5-year estimates
of carbon emissions from the IEA model. GISS outputs are estimates
of atmospheric temperature increases on a 5-year basis.
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APPENDIX E
COUPLING THE ORNL AND GISS MODELS TO ESTIMATE
THE RETENTION RATIO
As noted in Chapter 3, the ORNL and GISS models were coupled
in order to estimate that fraction of CO2 emitted which remains
airborne (the retention ratio). Recall that the rationale for
coupling the models is based on (1) the temperature-sensitive
representation of carbon flows in the ORNL model, and (2) the
superior treatment of atmospheric C02~temperature relationships
in the GISS model. The coupling procedures are diagrammed in
Figure E-l, and are described in this appendix.
CALCULATING INITIAL TEMPERATURE VS. TIME CURVES
The starting point is the estimation of a family of tempera-
ture-time curves using the GISS model. These curves are employed
in the ORNL model to describe a range of future increases in
atmosperic temperature (in response to rising atmospheric CO2)
which, in turn, will affect the rate of C02 exchange among sources
and sinks. In essence, the time trends in temperature, generated
through a more sophisticated (though still simplified) treatment
of heat flux in the GISS model, replace very simple CO2~tempera-
ture relationships in the ORNL model.
To generate the GISS temperature-time curves, it is first
necessary to estimate an atmospheric CO2~time curve which serves
as the main driving function for the GISS model. The most
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E-2
FIGURE E-l
KEY FEATURES OF THE ORNL-GISS COUPLING METHODOLOGY
Assumed
Retention Ratios
Fossil Fuel
Carbon Emissions
vs. Time
Giss Atmospheric
Temperature Model
V
Atmospheric
Temperature
vs. Time
V V V
ORNL Carbon
Cycle Model
Retention Ratio
vs. Time
Atmospheric
CO? vs. Time
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E-3
straightforward approach is to apply a series of assumed retention
ratios to the time trend of C02 emissions generated by the IEA
model. Values from about 0.6 in 1980 to about 0.8 in 2100 were
used to generate the preliminary atmospheric COg-time curves.
The GISS model is then run with high and low temperature -
CC>2 sensitivity (Te) values, with and without other greenhouse
gases, to produce a family of atmospheric temperature versus time
curves. These curves are represented by a quadratic equation of
temperature versus time with parameters a and b. The parameter
a is the temperature difference between 2100 and 1980, and b is
the temperature difference between 2040 and 1980 divided by a.
These parameters are then used to calculate coefficients for the
quadratic equation T = ct + dt2 + 293, where T is the temperature
rise after 1980 (°K) and t is the number of years after 1980.
Four new curves reflecting the extreme values observed
for a and b are then specified:
a
Highest
Lowest
Highest
Case 1
Case 3
Lowest
Case 2
Case 4
These curves bound all possible changes in temperature given the
time trend in atmospheric CC>2 specified previously. The four
combinations of values for a and b are then transmitted to the
ORNL model.
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E-4
CALCULATING CO? VS. TIME CURVES WITH THE ORNL MODEL
The ORNL model is next employed to estimate future increases
in atmospheric CO2, using the fossil fuel CO2 emission scenarios
from the IEA model and the four sea surface temperature-time
trends from the GISS model. Since four separate temperature -
time curves are employed, four separate C02~time curves are
generated as output. Each C02 curve is represented by estimates
of atmospheric CO2 concentrations in 10-year intervals from 1980
to 2100. Thus, a 4 by 13 matrix of values (corresponding to the
4 time vs. temperature curves and the 13 inclusive decades between
1980 and 2100) is generated as output.
ESTIMATING FINAL TEMPERATURE VS. TIME CURVES
The four "refined" time projections of CO2 are returned to
the GISS model to obtain a consensus temperature versus time
curve. This is accomplished by selecting one of the CO2 curves
as a starting point. (Tests demonstrated that starting from any
one of the four curves will yield the same result.) The GISS
model is then run to obtain a corresponding temperature curve
from 1980 to 2100. This temperature curve is compared with the
four temperature curves originally generated by the GISS model
and transmitted to the ORNL model. The new temperature curve is
composed by interpolating among the four previous curves, and a
new CO2 curve is estimated corresponding to the interpolated
temperature curve. (In essence, this is a two-way interpolation
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E-5
for each 10-year interval). The whole process is repeated until
two successive temperature curves closely approximate each other.
Usually, this takes no more than two iterations.
To check the "accuracy" of such an iterative approach, the
final temperature-time curve from GISS was used as input to the
ORNL model for a small sample of runs. The resulting C02~time
curve from ORNL was compared to the final CO2-time curve in GISS.
In all cases, the two agreed within 2 ppm for each 10-year
interval.
COMPUTING RETENTION RATIOS
Once the final atmospheric CO2 vs. time curve is obtained
from the ORNL, it is divided by the C02 emissions vs. time curve
to obtain a time-trend in retention ratios. In practice, 10-year
average values were computed. These were then used with estimates
of 10-year average CO2 emissions (from the IEA model) to compute
10-year average atmospheric levels of C02. These were used as
input to the GISS model for final estimates of atmospheric
temperature trends.
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GLOSSARY OF ENERGY UNITS
Definitions
Btu: British Thermal Units (Btus) are the basic energy
units in the English System. One Btu is the energy
needed to raise one pound of water one degree
farenheit.
Joule: Joules (J) are the basic energy units in the metric
system. One joule = 0.0009 Btus.
Abbreviations
Watt-hour: Wh*
Watt-year: Wy
Quad: 1015 Btus
Barrel of Oil Equivalent: boe
Metric Tons of Coal Equivalent: mtce
Cubic Feet of Gas: ft-* gas
Prefixes
Kilo(k): 103 Mega(M): 106 Giga(G): 109
Terra(T): 1012 Deta(D): 1015 Exa(E): 1018
Conversions
1.0 GJ
1.0 EJ
1.0 kWy
1.0 TWy
1.0 mtce
1.0 boe
1.0 ft3 gas
0.995 x 106 Btus
0.995 Quads
31.5 GJ
31.5 EJ
29.9 GJ
6.12 GJ
1.06 x 10~3GJ
Wh(e) means watt-hours of electrical energy
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