United States
Environmental Protection
Agency
Office of Policy
(2111)
EPA 236-F-98-007g
September 1998
Climate Change And Indiana
The earth's climate is predicted to change because human
activities are altering the chemical composition of the atmosphere
through the buildup of greenhouse gases — primarily carbon
dioxide, methane, nitrous oxide, and chlorofluorocarbons. The
heat-trapping property of these greenhouse gases is undisputed.
Although there is uncertainty about exactly how and when the
earth's climate will respond to enhanced concentrations of
greenhouse gases, observations indicate that detectable changes
are underway. There most likely will be increases in temperature
and changes in precipitation, soil moisture, and sea level, which
could have adverse effects on many ecological systems, as well
as on human health and the economy.
The Climate System
Energy from the sun drives the earth's weather and climate.
Atmospheric greenhouse gases (water vapor, carbon dioxide,
and other gases) trap some of the energy from the sun, creating
a natural "greenhouse effect." Without this effect, temperatures
would be much lower than they are now, and life as known today
would not be possible. Instead, thanks to greenhouse gases, the
earth's average temperature is a more hospitable 60°F. However,
problems arise when the greenhouse effect is enhancedby
human-generated emissions of greenhouse gases.
Global warming would do more than add a few degrees to today's
average temperatures. Cold spells still would occur in winter, but
heat waves would be more common. Some places would be drier,
others wetter. Perhaps more important, more precipitation may
come in short, intense bursts (e.g., more than 2 inches of rain
in a day), which could lead to more flooding. Sea levels would
be higher than they would have been without global warming,
although the actual changes may vary from place to place
because coastal lands are themselves sinking or rising.
The Greenhouse Effect
Solar
radiation
passes
through
the clear
atmosphere
Some solar radiation
is reflected by the
earth and the
atmosphere
Some of the infrared radiation passes
through the atmosphere, and some is
absorbed and re-emitted in all directions
by greenhouse gas molecules. The effect
of this is to warm the earth's surface and
the lower atmosphere.
Source: U.S. Department of State (1992)
Emissions Of Greenhouse Gases
Since the beginning of the industrial revolution, human activities
have been adding measurably to natural background levels of
greenhouse gases. The burning of fossil fuels — coal, oil, and
natural gas — for energy is the primary source of emissions.
Energy burned to run cars and trucks, heat homes and busi-
nesses, and power factories is responsible for about 80% of
global carbon dioxide emissions, about 25% of U. S. methane
emissions, and about 20% of global nitrous oxide emissions.
Increased agriculture and deforestation, landfills, and industrial
production and mining also contribute a significant share of
emissions. In 1994, the United States emitted about one-fifth of
total global greenhouse gases.
Concentrations Of Greenhouse Gases
Since the pre-industrial era, atmospheric concentrations of carbon
dioxide have increased nearly 30%, methane concentrations have
more than doubled, and nitrous oxide concentrations have risen
by about 15%. These increases have enhanced the heat-trapping
capability of the earth's atmosphere. Sulfate aerosols, a common
air pollutant, cool the atmosphere by reflecting incoming solar
radiation. However, sulfates are short-lived and vary regionally,
so they do not offset greenhouse gas warming.
Although many greenhouse gases already are present in the
atmosphere, oceans, and vegetation, their concentrations in the
future will depend in part on present and future emissions.
Estimating future emissions is difficult, because they will
depend on demographic, economic, technological, policy, and
institutional developments. Several emissions scenarios have
been developed based on differing projections of these under-
lying factors. For example, by 2100, in the absence of emissions
control policies, carbon dioxide concentrations are projected
to be 30-150% higher than today's levels.
Current Climatic Changes
Global mean surface temperatures have increased 0.6-1.2°F
between 1890 and 1996. The 9 warmestyears in this century all
have occurred in the last 14 years. Of these, 1995 was the warmest
year on record, suggesting the atmosphere has rebounded from
the temporary cooling caused by the eruption of Mt. Pinatubo in
the Philippines.
Several pieces of additional evidence consistent with warming,
such as a decrease in Northern Hemisphere snow cover, a
decrease in Arctic Sea ice, and continued melting of alpine
glaciers, have been corroborated. Globally, sea levels have risen
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Global Temperature Changes (1861-1996)
Year
Source: IPCC (1995), updated
4-10 inches over the past century, and precipitation over land has
increased slightly. The frequency of extreme rainfall events also
has increased throughout much of the United States.
A new international scientific assessment by the Intergovern-
mental Panel on Climate Change recently concluded that "the
balance of evidence suggests a discernible human influence
on global climate."
Future Climatic Changes
For a given concentration of greenhouse gases, the resulting
increase in the atmosphere's heat-trapping ability can be pre-
dicted with precision, but the resulting impact on climate is more
uncertain. The climate system is complex and dynamic, with
constant interaction between the atmosphere, land, ice, and
oceans. Further, humans have never experienced such a rapid rise
in greenhouse gases. In effect, a large and uncontrolled planet-
wide experiment is being conducted.
General circulation models are complex computer simulations that
describe the circulation of air and ocean currents and how energy
is transported within the climate system. While uncertainties
remain, these models are a powerful tool for studying climate. As
a result of continuous model improvements over the last few
decades, scientists are reasonably confident about the link
between global greenhouse gas concentrations and temperature
and about the ability of models to characterize future climate at
continental scales.
Recent model calculations suggest that the global surface temper-
ature could increase an average of 1.6-6.3°F by 2100, with signif-
icant regional variation. These temperature changes would be far
greater than recent natural fluctuations, and they would occur
significantly faster than any known changes in the last 10,000
years. The United States is projected to warm more than the
global average, especially as fewer sulfate aerosols are produced.
The models suggest that the rate of evaporation will increase as
the climate warms, which will increase average global precipita-
tion. They also suggest increased frequency of intense rainfall as
well as a marked decrease in soil moisture over some mid-
continental regions during the summer. Sea level is projected to
increase by 6-38 inches by 2100.
Calculations of regional climate change are much less reliable
than global ones, and it is unclear whether regional climate will
become more variable. The frequency and intensity of some
extreme weather of critical importance to ecological systems
(droughts, floods, frosts, cloudiness, the frequency of hot or cold
spells, and the intensity of associated fire and pest outbreaks)
could increase.
Local Climate Changes
Over the last century, the average temperature in Bloomington.
Indiana, has increased 1.8°F, and precipitation has increased by
up to 10% in many parts of the state. These past trends may or
may not continue into the future.
Over the next century, climate in Indiana may change even more.
For example, based on projections made by the Intergovernmental
Panel on Climate Change and results from the United Kingdom
Hadley Centre's climate model (HadCM2), a model that accounts
for both greenhouse gases and aerosols, by 2100 temperatures in
Indiana could increase by 2°F in summer (with a range of 1-4°F).
3 °F in winter and spring (with a range of 1 -6°F), and 4°F (with a
range of 2-7°F) in fall. Precipitation is estimated to increase by
10% in winter and spring (with a range of 5-20%), 20% in fall (with
a range of 10-40%), and 30% (with a range of 10-50%) in summer.
Other climate models may show different results, especially
regarding estimated changes in precipitation. The impacts
described in the sections that follow take into account estimates
from different models. The frequency of extreme hot days in
summer is expected to increase along with the general warming
trend. It is not clear how the severity of storms might be affected.
although an increase in the frequency and intensity of summer
thunderstorms is possible.
Precipitation Trends From 1900 To Present
Trends/100 years
+20%
+10%
+5%
-5% O
-10% O
-20%
Source: Karl et al. (1996)
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Human Health
Higher temperatures and increased frequency of heat waves may
increase the number of heat-related deaths and the incidence of
heat-related illnesses. Indiana, with its irregular, intense heat
waves, could be susceptible.
One study projects that heat-related deaths in Indianapolis could
increase by about 90% with a warming of 4°F, from about 3 5 to
about 65 (although increased air conditioning use may not have
been fully accounted for). This study also shows that winter-related
deaths in Indianapolis could double with a warming of 2-3°F.
However, the exact reasons for this increase are unknown. The
elderly, especially those living alone, are at greatest risk.
Climate change could increase concentrations of ground-level
ozone. For example, high temperatures, strong sunlight, and
stable air masses tend to increase urban ozone levels. A 2°F
warming in the Midwest, with no other change in weather or
emissions, could increase concentrations of ozone, a major
component of smog, by as much as 8%. Perhaps more important.
however, is that the area exceeding national health standards for
ozone could increase. Currently, Gary is classified as a "severe"
nonattainment area for ozone, and increased temperatures could
increase ozone concentrations further. Ground-level ozone is
associated with respiratory illnesses such as asthma, reduced
lung function, and respiratory inflammation.
Infected individuals can bring malaria to places where it does
not occur naturally. Also, some mosquitoes in Indiana can carry
malaria, and others can carry St. Louis and eastern equine
encephalitis, which can be lethal or cause neurological damage.
If conditions become warmer and wetter, mosquito populations
could increase, thus increasing the risk of transmission if these
diseases are introduced into the area. Increased runoff from
heavy rainfall could increase water-borne diseases such as
giardia, cryptosporidia, and viral and bacterial gastroenteritides.
Developed countries such as the United States should be able to
minimize the impacts of these diseases through existing disease
prevention and control methods.
Water Resources
Runoff in the state is largely determined by rainfall and to a lesser
degree by spring snowmelt. Earlier snowmelt would result in
higher streamflows in winter and spring. Lower streamflows, lake
levels, and groundwater levels in the summer could reduce water
availability for municipal, industrial, and agricultural uses.
particularly in southern Indiana where streamflow is variable and
groundwater supplies are not dependable. In the northern part of
the state, groundwater withdrawals for crop irrigation have grown
significantly. Lower groundwater levels in the summer, when
water demand is highest, could increase competition between
urban and agricultural uses. Higher summer temperatures and
lower flows also could harm water quality by concentrating
pollutant levels. This could increase water quality concerns in, for
example, highly industrialized and urbanized areas, where
improperly treated waste discharges have resulted in low dis-
solved oxygen and high levels of fecal coliform bacteria, heavy
metals, and organic compounds such as polychlorinated
biphenyls (PCBs).
Wetter conditions would increase streamflows and recharge
aquifers, but could increase flooding. The Maumee River basin.
and especially Fort Wayne, is vulnerable to major urban flood
damage. During wet periods, the numerous lakes in northeastern
Indiana are susceptible to shoreline damage. Higher rainfall also
could increase levels of pesticides and fertilizers in runoff. About
70% of the land in Indiana is used for agriculture, and runoff
containing fertilizers and pesticides can be problematic. These
problems could be exacerbated by greater runoff and flooding.
The southern shore of Lake Michigan is heavily industrialized in
Indiana. In a warmer climate, increased temperature and higher
evaporation could reduce freshwater inflows into the Great Lakes
and lower lake levels (studies suggest a foot or more for a 4°F
warming). Shorelines could be more susceptible to erosion
damage from wind and rain, but flood damage could be reduced.
Harbors and channels could require more dredging. Although
shipping could be adversely affected by lower water levels in the
channels connecting the lakes, reduced ice cover would lengthen
the shipping season. Warmer water temperatures could alter lake
water quality.
Agriculture
The mix of crop and livestock production in a state is influenced
by climatic conditions and water availability. As climate warms.
production patterns could shift northward. Increases in climate
variability could make adaptation by farmers more difficult.
Warmer climates and less soil moisture due to increased evapora-
tion may increase the need for irrigation. However, these same
conditions could decrease water supplies, which also may be
needed by natural ecosystems, urban populations, industry.
and other users.
Understandably, most studies have not fully accounted for
changes in climate variability, water availability, crop pests.
changes in air pollution such as ozone, and adaptation by farmers
Changes In Agricultural Yield And Production
Dryland Yield Production
Corn Soybeans
• AT = 9°F; Aprecip. = 5%
Corn Soybeans
AT = 9°F; Aprecip. = 12%
Sources: Mendelsohn and Neumann (in press); McCarl
(personal communication)
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to changing climate. Including these factors could change
modeling results substantially. Analyses that assume changes
in average climate and effective adaptation by farmers suggest
that aggregate U.S. food production would not be harmed,
although there may be significant regional changes.
In Indiana, production agriculture is a $5 billion annual industry.
60% of which comes from crops. Very few of the farmed acres
are irrigated. The major crops in the state are corn and soybeans.
Corn yields could fall 4-42% as temperatures rise beyond the
tolerance levels of the crop. Depending on how climate changes.
soybean yields could fall by 46% or rise by 15%. Farmed acres
could remain fairly constant, or they could decrease by as
much as 15%.
Forests
Trees and forests are adapted to specific climate conditions.
and as climate warms, forests will change. These changes could
include changes in species composition, geographic range, and
health and productivity. If conditions also become drier, the
current range of forests could be reduced and replaced by
grasslands and pasture. Even a warmer and wetter climate could
lead to changes; trees that are better adapted to warmer condi-
tions, such as oaks and pines, would prevail. Under these
conditions, forests could become more dense. These changes
could occur during the lifetimes of today's children, particularly
if the change is accelerated by other stresses such as fire, pests.
and diseases. Some of these stresses would themselves be
worsened by a warmer and drier climate.
With changes in climate, the extent of forested areas in Indiana
could change little or decline by as much as 60-75%. However, the
types of trees dominating those forests and woodlands are likely
to change. Forested areas would be increasingly dominated by
pine and scrub oaks, replacing many of the eastern hardwoods
common throughout Indiana forests. In areas where richer soils
are prevalent, southern pines could increase their range and
density, and in areas with poorer soils, which are more common in
Indiana's forests, scrub oaks of little commercial value (e.g., post
Changes In Forest Cover
Current +10°F, +13% Precipitation
Conifer Forest
Broadleaf Forest
Savanna/Woodland
Grassland
Sources: VEMAP Participants (1995); Neilson (1995)
oak and blackjack oak) could increase their range. Decreases in
soil moisture and on water supplies for irrigation could adversely
affect urban and suburban forests, where the migration of species
better adapted to new climate conditions would be impaired by
fragmented forest landscapes.
Ecosystems
The Indiana Dunes National Lakeshore, along Lake Michigan's
shoreline, ranks third of all U.S. national parks in plant diversity.
even though its acreage is less than 3% of that of the top two
(Great Smoky Mountains and Grand Canyon). These dunes
support some of the most extensive oak savannas remaining in
the United States and are home to such rare animals as the plains
pocket gopher, the blue spotted salamander, and several species
of endangered butterflies, including one of the world's only
populations of the Karner blue butterfly. The bottomland and
flood plain forests, bald cypress swamps, and oak-dominated
flatwoods of southwestern Indiana are known for their ecological
richness. Fish Creek contains one of the most diverse assem-
blages of freshwater mussels and fish in the Great Lakes basin.
and is the only place in the world where the white cat's paw
pearly mussel and two other federally endangered mussels are
found. The Wabash-Ohio lowlands natural system is on the
Mississippi flyway. It is an especially productive breeding
ground and an important stopover point for waterfowl, including
wood ducks. Indiana is well-known for its extensive limestone
cave systems, which support species such as caves salamanders.
blind cavefish, blind crayfish, and the endangered Indiana bat.
Higher-than-normal winter temperatures could boost tempera-
tures inside cave bat roosting sites, which has been shown to
cause higher mortality due to increased winter body weight loss
in endangered Indiana bats (e.g., an increase of 9°F during winter
hibernation has been associated with a 42% increase in the rate of
body mass loss).
Changes in climate threaten remaining wetlands, particularly for
ecosystems that lie within the Great Lakes basin. Recent studies
have shown that the largest hydrological impacts from warming
temperatures will be in the southern portion of the basin. If runoff
is reduced, wetland habitats that depend on inundation of
freshwater from the lake could be adversely affected. An increase
in climatic variability suggests that frequency and severity of
wildfires could increase, which could affect already dry sites such
as sand dune and oak savannah habitats. The small area and
history of fire suppression in these ecosystems could increase
their vulnerability. Wetlands play a major role in river basin
hydrology and serve as important wildlife habitats. Changes in
water levels brought about by a changing climate could dramati-
cally alter the extent of these ecosystems and endanger resident
flora and fauna. For example, warmer air temperatures could lead
to reduced stream flow and warmer water temperatures, which
would significantly impair reproduction offish and other animals
and favor the spread of exotic species that exhibit a high
tolerance for extreme environmental conditions.
For further information about the potential impacts of climate
change, contact the Climate and Policy Assessment Division
(2174), U.S. EPA, 401 M Street SW, Washington, DC 20460, or
visit http://www. epa.gov/globalwarming/impacts.
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