Environmental  Protection Technology  Series




                           Alden McLellan IV

                     Institute for Environmental Studies
                     University of Wisconsin - Madison
                         1225 West Dayton Street
                        Madison, Wisconsin  53706


                         M. W. Kellogg Company
                      1300 Three  Greenway Plaza East
                         Houston, Texas 77046
                     Contract No. 68-02-1308 (Task 29)
                          ROAP No. 21ADE-010
                       Program Element No. 1AB012
                    EPA Project Officer:  Irvin A .  Jefcoat

                       Control Systems Laboratory
                   National Environmental Research Center
                 Research Triangle Park, North Carolina  27711
                             Prepared for

                        WASHINGTON, D.C.  20460

                             October 1974

This report has been reviewed by the Environmental Protection Agency
and approved for publication.  Approval does not signify that the
contents necessarily reflect the views and policies of the Agency,
nor does mention of trade names or commercial products constitute
endorsement or recommendation for use.


                           Alden  McLellan IV
                             IES  REPORT  31
                       Center for Climatic Research
                    Institute for Environmental Studies
                     University of Wisconsin - Madison
                             15 October 1974
This study was made possible by a grant to the  Institute for Environmental Studies
from the M. W. Kellogg Company as subcontractors under the United States Environmental
Protection Agency, Contract Number 68-02-1308.

                               TABLE OF CONTENTS



       A.   SOLAR RADIATION   	  5
            1.  Distribution of Solar Radiation 	  5
            2.  Solar Radiation Over Large Time Scales 	  6

       B.   CARBON DIOXIDE  	  6
            1.  Past and Future C02 Concentration Increase 	  6
            2.  The Effect of C02 on the Global Heat Budget	  7

       C.   HEAT	  9
            1.  Ocean-Atmosphere Heat Exchange	^	%	v	  9

       D.   PARTICULATE MATTER  	 10
            1.  Global Emission of Particulates 	 11
            2.  Natural Particulates - Volcanic Activity 	12
            3.  Man-Related Particulates  	•	13
            4.  Jet Aircraft Particulate Emissions 	13
            5.  Lead - A Man-Made Pollutant Indicator 	 15
            6.  Atmospheric Residence Time for Lead   	15
            7.  An Erroneous Estimation for the Residence Time	16
            8.  Analogy to Atmospheric Particulates 	 16
            9.  Worldwide Distribution of Locally Emitted Particulates 	16
           10.  Evidence for Global Movement of Local Particulate Matter ....16
           11.  Dynamical Means of Worldwide Particulate Loading  	17





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In the past few years, many of the populated areas of the earth have experienced
disastrous weather.  India's harvests have been decreasing.  The monsoon rains
in India and Africa have been late.  The Sahara has expanded relentlessly south-
ward.  Russian wheat crops have failed.  In Central America, crops failed,
cattle starved and the intensity and frequency of hurricanes have increased.
Floods and frost in the Midwest and drought in the Southwest have curtailed
U.S. grain production.  Best & Co. has reported that due to weather disaster
the property/liability index of U.S. fire and casualty companies has dropped
over 50% in the first eight months of 1974 (Barrens, 1974).  The earth's
climate is changing.

The main force driving the climate of the earth-atmosphere system is radiation.
The incoming solar energy absorbed by this system is in approximate balance
with the outgoing infrared radiant energy.  However, variation in the earth's
rotation, the radiation of the earth's surface, and the composition of the
atmosphere are very important factors, for they govern the nature and magni-
tude of changes in the heat balance.  This balance may be expressed mathe-
matically as follows:

               S(l-a ) = 40T4         + m* _8T
                            effective      8t

where          S = the incoming solar radiation,

              a  = outside albedo at the top of the earth's atmosphere,

               a = Stefan-Boltzman constant,
       effective = effective outside radiative temperature of the earth-
                   atmosphere system,
              M* = effective mass of the earth-atmosphere system,

              T  = mean atmospheric temperature.

The term on the left-hand side of the equation represents the incoming energy,
and the first term on the right-hand side represents the outgoing energy.  The
second term on the right-hand side represents the heat storage of the atmosphere-
ocean system which is quite sensitive and is indicative of climatic changes.

We have  considered the various components of the earth's energy budget,  their
magnitudes and relative importance, the  influence of man's activities on the
processes governing  climatic  change and  the prospects concerning the future.

In this paper we have endeavored to estimate the effect of small changes of inde-
pendent climatic variables on the global energy budget.   In providing a discussion
of these changes, we have approached the problem from an historical perspective.
We have also investigated the components of these changing variables as to whether
or not their change is due to natural causes or to man-related activities.  At the
end of our paper we arrive at conclusions as to the importance of climatic change
and what man can do to better define the problems related to the variables that
affect the energy budget.

The energy input necessary to drive the atmosphere's circulation comes from
the intensity of sunlight at the top of the earth's atmosphere.  From long-
range historical evidence, we conclude that variation in this extrinsic para-
meter performs a minor role in decadal to millennial energy budget changes.

Carbon dioxide, another extrinsic climatic variable, is important in determining
the temperature of the earth, since it absorbs and emits infrared radiation.  If
the increase in C02 were the only change in the energy budget, the earth's surface
temperature should have been steadily rising at an increasing rate over the last
century.  However, observations have shown this has not been the case.

Estimates of emission and retention of particulate matter in the atmosphere lead
us to conclude that this extrinsic parameter could indeed account for the mean
annual change in temperature during the past century.  By using lead as an indi-
cator of man-related activities in atmospheric particulate emission, we esti-
mate that 40%-50% of suspended solid matter in the earth's atmosphere is due to
man.  We have found that particulates from jet aircraft alone presently contri-
bute approximately one-half the amount of stratospheric particulates as presently
injected by natural volcanic activity.  Locally emitted particulates from industrial
activities, from agricultural processes, such as slash-and-burn clearings, and
from windswept areas due to the overgrazing of land, can be distributed over the
hemisphere in a relatively short time.

Since population, agricultural mechanization and industrialization are still
expanding throughout the world, there is little that any one nation alone can do
to reverse the trend of particulate emissions on a global scale.  In order to
obtain better data, we can search for other meaningful trace atmospheric con-
stituents that parallel particulate emission and distributions.  In particular,
we should explore those trace constituents that are indicative of man's activities,
such as DDT, as well as those that are indicative of natural causes.  Also, the
modeling of pollutant dispersion and behavior over large distance and time scales
should be more intensively investigated.


There is abundant evidence that the earth's climate is subject to a wide variety
of fluctuations, with periods ranging from decades to millenia, and that it is
now changing.  The atmosphere is a relatively stable system.  The energy input,
in the form of solar radiation, is absorbed by the earth and it is almost exactly
balanced by the emitted terrestrial infrared radiation, otherwise the mean temp-
erature would change much more rapidly than it does.  This nearly perfect balance
is the key to the heat budget changes that have occurred in the past, are occurring
now, and will occur in the future.

Variations in parameters both extrinsic and intrinsic to atmospheric processes
serve to modify the climate.  For a discussion of extrinsic and intrinsic climatic
variables, see Bryson (1974).  We shall be concerned here with parameters ex-
trinsic to the internal feedback mechanisms of the atmosphere itself.  The important
leverage points of the extrinsic control variables of climatic change concern
the radiation balance of the atmosphere, and they control it by fundamentally
changing the composition of the atmosphere.  For example, the heat balance can be
changed significantly by altering the delicate radiation balance described above
by changing solar radiation, content of C02 and particulate matter concentration.
In discussing the various important atmospheric components below, we will estimate
the present order of magnitude of change in these components.


The annual average total radiation per  unit  time incoming at the top of the
earth's atmosphere on a unit surface  perpendicular to the sun's rays (defini-
tion of the solar constant) is  1.95 cal cm"2 min -1 (136.0 mW/cm2) (Drummond,

New active cavity radiometers have been developed for the absolute measurement
of optical radiant flux.  Using these new radiometers the solar constant was
measured at an altitude of  25 km.  It was determined to be 137.0 mW/cm  with
an absolute uncertainty of  less than  ±  2% (Willson, 1971).  Changes of the
solar constant, even of the order of  1  percent,  have not been firmly established
even though there have been many suggestions of  variations (Kondratiev and
Mikolsky, 1970) including variation in  sun spot  activity and solar flares.

1.   Distribution of Solar  Radiation

The fundamental regimes that  govern the distribution of solar energy act con-
tinuously (or quasi-continuously) within the earth's atmosphere or at its
boundaries.  The numerical  rates in the schematic Figure 1 are given relative
to the  incoming solar energy  available  at the top of the atmosphere.  Radiative
regime  I describes  the effect  of primarily atmospheric carbon dioxide as it
affects the long wavelength portion of  the radiation budget.  Radiative regime II
describes for the most part the effect  of atmospheric particulates on the short
wavelength portion, and regime III  contains the effects of the lower boundary
and clouds.
                                  [ 500
                                                         Constant  |
     27      177     21
&8fi V\	7>	XX	
IMOSfKttf               I
,-201  121   120
            lAITH'S .
                        -177 4fN

                        545     |
                   -28 3
       72  -112
            Figure 1.   The distribution of solar radiation within the earth's
                       atmosphere and at its boundaries.  The numerical rates of
                       radiative energy transfer are relative to the solar energy
                       constant.  (Budyko and Kondratiev, 1961; Lettau, 1973.)

On an annual average, twice the solar radiation available at the poles is avail-
able at the equator, because the incoming solar radiation on a unit horizontal
surface is more direct in equatorial than in polar regions.  Outgoing radiation
depends strongly on the effective temperature of the atmosphere, but this tempera-
ture does not vary much from equator to pole.  Thus, there is only a small change
of emitted radiation with latitude (Viebrock and Flowers, 1965, 1968).  Hence,
there is an excess of incoming solar radiation over emitted infrared radiation
in equatorial regions and a deficit in the polar regions.  Large-scale atmospheric
circulation forced by the unequal geographic heating and cooling is made quite
complicated due to the earth's rotation and topography.  However, these atmospheric
motions, together with radiative processes, help produce the two fundamentally
distinct layers within the atmosphere; the troposphere and stratosphere.  The
qualitative difference in lapse rate between these two layers and the tropospheric
scavenging processes lead to an important difference in the residence times of
various atmospheric constituents in these two regions.  A knowledge of the growth
rates and lifetimes of these constituents can give an estimate of future climatic
changes.  This will be considered later in more detail.

2.   Solar Radiation Over Large Time Scales

The total incoming solar radiation also depends on the earth-sun distance and on
the solar elevation angle.  These depend on the earth's orbital characteristics,
such as the orbit's eccentricity, the obliquity of the ecliptic, and the longi-
tude of the perihelion with respect to the spring equinox.  As calculated from
celestial mechanics, these orbital elements show very slow variations with periods
on the order of 105 years for the eccentricity, 4x10  years for the obliquity,
and about 2.1xl04 years for the precession period.  The variations of solar radia-
tion input with respect to these orbital parameters were also studied extensively
by Milankovich (1930), Broecker (1968), and Kutzbach, et al.  (1968).  Surface
temperature fluctuations during the past AxlO5 years may have been influenced by
changes in these orbital elements (Emiliani, 1966), but the time scales of these
cycles are on the order of 104 to 105 years.  Thus we conclude that this varia-
tion in sunlight intensity at the top of the atmosphere plays a minor role in
decadal to millennial energy budget changes.


Carbon dioxide is a trace gas within the atmosphere with a concentration of about
320 ppm (0.03% by volume).  It is increasing about 1 ppm annually  (Machta, 1972).
Even though it is only a trace gas, it has an important role  in determining the
temperature of the earth by being an efficient absorber and emitter of  infrared
radiation.  By absorbing the infrared radiation that is emitted by the  earth's
surface and reradiating it back toward the earth, the rate of surface cooling is
decreased.  It is just this effect that can cause atmospheric temperature varia-
tions from changes in C02 concentration.

1.   Past and Future C02 Concentration Increase

Measurements of the carbon dioxide concentration have only been made on a systematic
basis since 1958.  These observations, from Swedish aircraft  (Bolin and Bischof,
1969), at Point Barrow (Kelley, 1968), in the Antarctic  (Brown and Keeling, 1965),
and at Mauna Loa, Hawaii (Pales and Keeling, 1965) distinctly show the  increase
in concentration of C02 over the past decade (see Figure 2).

       •" 316
       "5 314
            Year  1958

            OSwediih flighti
Q Mauna loa
 1968      1970
0 Barrow, Alaska
          Figure  2.  Annual  mean values of CC>2 atmospheric concentration.

Both carbon dioxide  and water vapor play important roles in modifying the verti-
cal temperature distributions of the atmosphere by controlling the energy input
and output via absorption and emission of infrared radiation.  Whereas, water
vapor concentration  is an atmospheric intrinsic variable, in that it responds
directly t-o the climate,  carbon dioxide is an extrinsic variable, in that it is
regarded as not responding to climate but rather to the consumption of fossil
fuels (Machta, 1972).

Estimating future atmospheric C02 concentration depends on estimating the growth
rate of man's use of fossil  fuels and on the partitionings of C02 sinks among
the atmosphere, oceans, and  biospheric reservoirs.   Estimates of this partitioning
are uncertain at  the present.   However, if we assume a 4% annual growth in fossil
fuel combustion and a continuation of the partitioning found during the 1958-
1968 period, an increase  in  atmospheric C02 over the present levels of almost
20% by the year 2000 (from 320 to 379 ppm)  can be expected.

2.   The Effect of C02 on the Global Heat Budget

The question to ask at this  time is  what effect would this man-made increase of
C02 have upon the earth's  climate,  all else being equal.   Manabe and Wetherald
(1967) have developed a model for calculating the effect  of  C02 concentration
changes on the surface temperature  of the earth.   This model, which puts the entire
atmosphere in radiative-convective  equilibrium,  allows for the overlapping of the
15y band of C02 and the rotation band of water vapor.   The model's atmosphere had
a fixed relative humidity, a  specified distribution of 03 and included clouds.   For

an increase in C02 concentration  from  300  to  600 ppm,  their model raises the
earth's surface temperature by  2.36°C.
The relationship between
From Figure 3 we obtain
                             concentration  and  surface temperature is non-linear.

                         AVERAGE CLOUDINESS
                           290     295      300     305
                                Temperature (°K)
           Figure 3.  Equilibrium temperature of the earth's surface and the
                      carbon  dioxide  concentration of the atmosphere.  Note
                      the  exponential relationship.   The data are from Manabe
                      and  Wetherald  (1967).

                    T = k  log (C02),

where k is a constant.

For small changes, we obtain
Since the temperature increases by  2.36°C for a doubling of C02 concentration, we

                    k =  2.36°C.

A change of C02 concentration  of  20% over present levels, represented by a change of

                    A(C02) = 60 ppm by the year 2000,

results in an increase in global average annual temperature of approximately
0.47°C.  This is about 2/3 of that predicted in the report "GLOBAL ENERGY
BALANCE" by InterTechnology Corporation (1973).

If this increase in carbon dioxide were the only cause of changes in the energy
budget, then the mean global surface temperature should have risen steadily and
smoothly at an increasing rate over the last century by about 0.25°C (Bryson,
1974).  However, observations of mean global surface temperature have, in fact,
shown a decrease since 19AO.  Thus, there are clearly other extrinsic parameters
of greater importance that are influencing climatic change as far as surface
temperature is concerned.


Heat emitted into the atmosphere from man's activities of energy generation and
consumption is a direct addition to the earth's energy budget.  It is well-
known that a concentration of heat sources in an urban area can indeed modify
the local climate (Peterson, 1969).  On the global scale, however, man-generated
heat is not a significant factor in the heat budget because it adds much less
than 1% to the net radiation average.  From the 1969 United Nation's report,
World Energy Supplies (SCEP, 1970), the thermal power of the world is estimated
to be 5.5xlOb megawatts (MW).  Greenfield (1970) assumed a world growth rate of
5.7% annually, and arrived at 31.8xl06 MW by the year 2000, a six-fold increase.
If we average the present day heat power over the entire globe (5xl08 km2), we
have a heat density of l.lxlO"12 MW/cm2 or l.lxlO"6 W/cm2, which can be compared
with either the solar constant, 1.36xlQ~1 W/cm2, which is the solar radiation
incoming at the top of the earth's atmosphere, or the continental net radiation
average of 6.7x10"^ W/cm2 (SMIC, 1971).

In order to put man as a heat-generating source into perspective with other
natural sources, Table 1 lists various heat inputs into the earth's atmosphere.
It is to be noted that the annual rate of fossil-fuel burning by man is of the
same order of magnitude as the infrared radiation energy received from a full moon.

Heat from man's activities over the past three decades is a small fraction of the
global energy budget.  However, there are local conditions and indirect feedback
situations where a large amount of geographically concentrated heat can modify the
water vapor content and cloudiness (albedo), which are intrinsic climatic para-
meters that can modify the heat budget over fairly large geographic areas.

1.   Ocean-Atmosphere Heat Exchange

An example of an intrinsic climatic factor is the sea surface, whose optical and
thermal properties are variable and depend strongly on long-term average condi-
tions in the atmosphere.  The ocean mass is hundreds of times that of the atmosphere,
but its properties cannot be rapidly changed in depth.  However, the surface
layers can change annually.

The contribution of the ocean heat transport to the global heat budget has been
estimated for various latitudinal belts (using mostly Atlantic weather-ship data)
by Budyko (1971).  These data indicate that the heat transport produced by the
oceans serves to moderate atmospheric heat differentials.  Large scale oceanic
fluctuations can result in temperature perturbations of a degree or so within
latitudinal belts.  Meridional heat transport produced by oceans leads to readjust-
ments of the distribution of the atmospheric heat budget, but it cannot produce

                                   TABLE 1

                                                             (109 Watts)
     1/4 Solar Constant (extra-atmospheric irradiance)       178,000,000
     Insolaton Absorbed at Ground Level                       90,000,000
     Dissipated by Friction in Atmospheric Circulations        1,500,000
     Photosynthesis (production by living vegetation)             40,000
     Geothermal Heat (by conduction in crust)                     32,000
     1970-Rate of Fossil-Fuel-Burning by Man                       8,000
     Infrared Radiation From Full Moon                             5,000
     Dissipated by Friction in Ocean Currents and Tides            3,000
     Solar Radiation Received via Reflection from Full Moon        2,000
     Dissipated by Friction in Solar Tides of the Atmosphere       1,000
     1910-Rate of Fossil-Fuel-Burning by Man                       1,000
     Human Body Heat                                                 600
     Released by Volcanoes and Hot Springs (geo-convection)          300
     1960-Rate of Hydroelectric Power Production                     240
     Dissipated as Heat in Lightening Discharges                     100
     Radiation from Bright Aurora                                     25
     Received from Space by Cosmic Radiation                          15
     Dissipated Mechanical Energy of Meteorites                       10
     Total Radiation from all Stars                                    8
     Dissipated by Friction in Lunar Tides of the Atmosphere           5
     Solar Radiation Received as Zodiacal Light                        2

long-term global trends.  However, there is no doubt that the oceans affect the
world's climate in very important ways.  As an intrinsic parameter, it reduces
the latitudinal temperature gradients and reduces the atmospheric seasonal tempera-
ture variations.


Suspended particles are observed throughout the entire earth's atmosphere.  These
particles have an effect on the global energy budget by their modification of the
atmospheric radiation balance through the scattering and absorption of light
(McCormick and Ludwig, 1967).  The sizes of the particles that are suspended in
the atmosphere range from about 10~7 cm (10~3y) to about 10~2 cm  (102y).  In
general, these particles produce Mie scattering in which most of  the radiation is
scattered in the forward direction.  Some of the radiation is scattered into
space, some of it is absorbed, some reaches the surface of the earth and is
absorbed there.  Thus, these atmospheric particles can change the total sunlight
scattered by the earth into space.  In this way, the global albedo is modified.
However, these particles also radiate energy in the infrared spectrum modifying
the field of terrestrial radiation in a manner that depends on the optical proper-
ties of the particles and the temperature structure of the atmosphere (Peterson
and Bryson, 1968A, 1968B).

Atmospheric particulate matter can produce important changes in the global heat
budget, but the sizes, types, and concentrations of particles respond only in
*  These whole globe averages represent annual gigawatts (109W) of power
   totaled over the earth's surface (Lettau, 1973).


part to the climate.  If for some reason surface winds increase, more particu-
lates are blown up into the atmosphere, which will tend to cool the earth, which
in turn may modify the wind patterns.  There is a feedback process.  But parti-
culate matter is a variable that for the most part is extrinsic to the heat
budget, in that the quantity and quality of particles depends on the entry into
the atmosphere of soil, rock and chemical debris through natural and man-made
processes (Peterson and Junge, 1971).  In fact, an evaluation of man's contri-
bution relative to those of natural processes is particularly desirable since
it is quite substantial and is amenable to control.

1.   Global Emission of Particulates

Estimates of the magnitude of emission or formation of particles less than about
20p radius in the lower part of the atmosphere are given in Table 2 with the
range of values that can be found in the literature.  From the wide range in
many of these estimates, it can easily be seen that there is very little precise
data on global particulate emissions and a wide disparity in assumptions made to
arrive at these estimates.

                                   TABLE 2 *


     Atmospheric Particulates
     from Natural Sources

     1.  Soil and rock debris (natural)                      50-250 (105 metric
     2.  Forest fires (natural)                                1-50
     3.  Sea salt                                             (300)
     4.  Volcanic debris                                     25-150
     5.  Particles formed from gaseous emissions:
         H2S, NH3, NO , and hydrocarbons                   345-1100


     Atmospheric Particulates from Man-Made
     and Man-Accentuated Sources	

     1.  Soil and rock debris (agricultural)                 50-250
     2.  Forest fires and slash-burning agric.                2-100
     3.  Particles  (direct emission)                          10-90
     4.  Particles from gaseous emissions:
         S02, NO , and hydrocarbons                         175-325


The estimates used in Table 2 can be found in Goldberg, 1971; Robinson and Robbins,
1971; Peterson and Junge, 1971; Hidy and Brock, 1970; Mitchell, 1970; Went, 1970;
Shannon, et al., 1970; and NAPCA, 1970.
*  Original data taken from SMIC Report, 1971.


In some cases It is quite difficult to assign the origin of these particulates
to direct human activities, to historic or even prehistoric misuse of the land
(such as overgrazing), or to natural phenomena.  Lacking any other information,
we divided the soil and rock debris estimate into two equal categories; one
from man-made and man-accentuated sources; the other from natural sources.
Forest fires and slash-burning agriculture were also equally divided.  Slash-
burning agriculture is wholly due to man, but many forest fires are also man-caused.

From Table 2, we see that particulate matter arising from man's activities ac-
counts for 40% to 50% of all particulates in the earth's atmosphere.  The rela^
tive variability of the "natural" and "man-made" portions of the atmospheric
particulate load is as important as the relative magnitude; however, it has not
yet been adequately explored.

2.   Natural Particulates - Volcanic Activity

Volcanic activity has probably been the most important variable source of atmospheric
particulates throughout history.  Its variability matches that of climatic changes.
Hamilton and Seliga (1972) have convincingly shown that the temperature over the
Greenland and Antarctic ice sheets decreases as the volcanic dust falling on those
ice sheets increases (and vice versa) over the past hundred millenia.  Bryson
(1971) and Reitan (1971) have shown that in the last hundred years a major con-
trol of the global mean temperature in the Northern Hemisphere has been volcanic
dust augmented by man's contribution.

Budyko (1969) has shown from direct measurements of the solar radiation normally
incident at the ground under cloudless skies that the atmospheric transmittance
varied during the past century such that the highest values occurred in the
warm period of the 1920's and 1930's, when volcanic activity was at a minimum.
All of the above facts imply that, throughout history, as volcanic activity in-
creased, atmospheric particulate loading increased, more solar radiation energy
was reflected back into space and the mean global temperature of the earth de-
creased (and vice versa).  However, in the past thirty years something new has
occurred.  Volcanic activity was at a relatively low ebb until the fifties when
it began to increase.  One would expect that a global cooling would follow this
increase in activity, but both the mean temperatures as well as the measured
radiation intensity in the Northern Hemisphere began to decrease well before the
1950's.  This suggests another source of atmospheric particulate loading which
became significant by 1940 (Bryson, 1974; Flowers, McCormick and Kurtis, 1969).

Mitchell (SCEP, 1970) has calculated that the average stratospheric loading of
very fine particulate matter (0.1 - l.Op) due to volcanic activity over the past
century was about 4.2 million metric tons.  He assumed that only 1 percent of the
ejected matter from the major eruptions reached the stratosphere, and he assumed
a residence time of 14 months.  If we assume a steady state situation, this
implies that an average of 3.6 million metric tons of volcanic particulates was
injected into the stratosphere in an average year over the past century.  Lamb
(1970) has compiled a "Dust Veil Index" (D.V.I.) that is an indicator of atmospheric
particulate loading due to worldwide volcanic activity.  Lamb (1970) obtained an
average D.V.I, of 300 over the past century, but, due to the decrease in volcanic
activity after 1915 or so, he obtained an average of less than 10 for the Dust
Veil Index over the past three decades.  If Mitchell's estimation of 3.6 million
metric tons/year for an average over the past century  corresponds to a D.V.I.
of 300, we arrive at the annual average of 120,000 metric tons/year of volcanic
particulates injected into the stratosphere over the past three decades cor-
responding to a D.V.I, of 10.  Presently, commercial jet aircraft alone emit
particulates into the stratosphere at one-half of this rate, as discussed below.

 3.   Man-Related Particulates

 If  the  increase in man's activities  is  the  source  of  this  increased  particulate
 material,  then there  should have been a nearly  exponential increase  in  the
 atmospheric  loading from man's by-products  in the  middle third  of  this  century.
 A number of  observations indicate  that  this has indeed  been the case (Peterson,  1969),

 In  the  drier monsoon  region the explosive population  growth has led  to  overuse of
 the land and extreme  dust  loading  of the atmosphere  (Carlson and Prospero,  1974),
 and in  the wetter tropical regions,  an  increase in agricultural slash-and-burn
 rotation rates has led to  increased  production  of  smoke.

 A rapid increase of dust fall on the Caucasian  and Altai (Davitaya,  1974) snow-
 fields  began about 1930 to 1940, indicating at  least  a  rapid increase in  soil
 deflation  in eastern  Europe or the Near East.

 A similar  increase in the  lead fall  on  the  Greenland  ice cap shows the  same
 pattern (Murozumi, et al., 1969).  Figure 4 shows  the variation of anthropogenic
 lead dust  fall at Camp Century, Greenland, from  about  1880  to 1960  showing the
 rapid increase in man-made particulates since 1930.
          Figure 4.  Variations of man-made lead dust fall at Camp Century,
                     Greenland, from about 1880 to 1960.  Note the rapid
                     increase in atmospheric lead since 1930.  The concen-
                     tration is measured in parts per billion (ppb).   (After
                     Murozumi, 1969).

4.   Jet Aircraft Particulate Emissions

Downie (1974) made a study of transcontinental commercial jet aircraft flights
over the United States and the North Atlantic.  He found that during the winter
months these aircraft were cruising above the tropopause almost 90% of the time.
At these higher latitudes, the tropopause is generally low during the cold season.


The following data on particulate emissions of commercial jet engines was given
by Forney  (1974).  Low smoke engines are those that power the 747, DC10 and
the L1011.  The cruise altitude for these planes is on the order of 30,000 to
35,000 feet at a speed of MACH 0.85.  At 35,000 feet at maximum thrust the fuel
flow per engine is 2900 kg/hr.  At 80% of maximum thrust the flow is 2250
kg/hr.  At 30,000 feet at maximum thrust the fuel flow is 3300 kg/hr, and at
80% of maximum thrust the flow is 2700 kg/hr.

On the average, the emission index (E.I.) for carbon particulates under the above
cruise conditions is 0.02 gm/kg of fuel.  For the Boeing 707 engines under similar
conditions, the carbon particulate E.I. is 0.1 gm/kg.  For an E.I. of 0.1 gm/kg,
the size distribution is as follows:

     35% of the carbon particles are less than O.Oly
     60% "   "    "       "       "    "    "  O.OSy
     75% "   "    "       "       "    "    "  O.lOy
  99.85% "   "    "       "       "    "    "  0.50y

Not only are carbon particulates emitted, but also sulfur particulates (aerosols)
are emitted.  If we assume a sulfur component in the fuel of 0.05% by weight,
the emission index for sulfur dioxide is 1.0 gm/kg of fuel.  (Also, if we assume
an hydrogen-carbon ratio of 2 for the fuel, the E.I. for water is 1300 gm/kg.)

The world  fleet of operational commercial jet aircraft totals about 5,100 (Irons,
1974).  The annual average worldwide utilized flight time per day per jet air-
craft is on the order of 7-1/2 hours (Irons, 1974).  In order to estimate the
carbon particulates emitted into the stratosphere due to jet aircraft, let us

     1.  A mixture of types of engines, 2700 kg/hr of fuel flow/engine;
     2.  An average of three engines per aircraft;
     3.  An annual average of 7-1/2 hours flight time per day for 5,100 jet
         commercial aircraft;
     4.  An average emission index (E.I.) for carbon of 0.05 gm/kg; and
     5.  Neglect all military aircraft operations  (military operations are
         approximately 10% of commercial operations).

Let us also assume that for 90% of the time during one-third of the year, these
aircraft cruise above the tropopause.  Then from these data, we arrive at 1696
metric tons of carbon particulates from commercial jets emitted into the strato-
sphere each year.

Engine residue also consists of sulfur dioxide and sulfur trioxide particulates
which are oxidized in the lower stratosphere through photochemical reactions.
Sulfur trioxide immediately hydrolizes to form sulfuric acid,  l^SO^,
and samples show that these I^SO^ droplets are usually on the order of tenths
of a micron in size (Cadle, et al., 1970).  Since  the E.I. of sulfur dioxide is
twenty times that of the carbon particulates, and  the t^SO^ weight equivalent of
sulfur dioxide is 98/64 times the sulfur dioxide,  this increases the loading
of particulates in the stratosphere to 33,900 metric tons/year due to sulfur
dioxide alone; or about 52,000 metric tons/year of l^SOi^ particulates.  Thus,
commercial jet aircraft emit over 50,000 metric tons of particulates a year into
the stratosphere.  This is to be compared with volcanic activity, which injects
particulates into the stratosphere at approximately twice this rate  (120,000
metric tons/year, see above).

5.   Lead - A Man-Made Pollutant Indicator

Lead is one trace substance in the atmosphere that is due wholly to man's
activities.  Natural sources contribute only insignificantly to present con-
centrations of atmospheric lead (LEAD, 1972).  An accurate estimation of con-
temporary natural lead background is difficult since man has mined lead for
many centuries.  Natural concentrations have been estimated to be about
0.0005 ng/m3 (Patterson, 1965) from airborne dust containing on the average
10-15 ppm of lead (Chow and Patterson, 1962) and from gases diffusing from the
earth's crust  (Blanchard, 1966).  This amount is insignificantly small.  Data
from the National Inventory of Air Pollutant Emission and Controls of the
Environmental Protection Agency in Research Triangle Park, North Carolina, show
that the inorganic emission from the combustion of leaded gasoline constitutes
approximately 98% of the total emission (184,000 tons/year) of lead into the
atmosphere directly from man's automotive activities within the United States.
Thus, there is geographically, a logarithmic increase in atmospheric lead con-
centration from mid-ocean to the seashore, to suburban and urban environments.
There is far less lead in mid-ocean than near urban environments, so that if one
is to attempt to get a handle on the concentration build-up and atmospheric
scavenging time of particulates due to man's activities by using an analogy with
the lead data, one must proceed with caution.

From Table 2, we see that the yearly global aerosol production is on the order
of 109 tons of which about 50% are anthropogenic.  The amount of particulates
that is retained from this aerosol generation can be estimated from the known
values of lead production and lead content.  From above, the yearly release of
lead into the atmosphere in the United States is on the order of 2xl05 tons/year
and that almost all of this is due to man  (mostly from the use of leaded gaso-
line) .  Goldberg and Gross (1971) have estimated the global yearly release of
lead into the atmosphere to be 610,000 tons.  The National Academy of Sciences
(1973) has misquoted the results of Goldberg and Gross (1971) by indicating that
one-third of the global emission of lead into the atmosphere is due to natural
sources.  In fact, only an insignificant portion of the total comes from natural
sources (LEAD, 1972).

Annual ice layers from the interior of northern Greenland show that lead concen-
trations increased from less than 0.0005 yig/kg of ice at 800 B.C. to more than
0.2 Pg/kg in 1965 (Murogami, 1969).  The sharpest rise occurred after 1940
(see Figure 3).  However, in the Southern Hemisphere the rise in lead concen-
tration after 1940 was not as sharp.  In the Antarctic continental ice sheet the
concentration rose only to 0.02 pg/kg after 1940.  This difference is ascribed to
barriers to north-south tropospheric mixing, which hinder the migration of aerosol
pollutants from the Northern Hemisphere, where most industrial emissions occur,
to the Antarctic.

In most cities, the average atmospheric concentrations of lead in 1953-1966 ranged
from 1 to 3 Pg/m3, but non-urban stations averaged 0.1 - 0.5 ^g/m3, and the con-
centrations at very rural stations were less than 0.05 Pg/m3 (U.S.H.E.W., 1962,
1966, 1968).  McMullen, et al., (1970) showed that in remote areas an average
concentration of 0;022 yg/m3 exists.  Let us assume an average worldwide concen-
tration of 0.02 yg/m3.  From this figure we will estimate the atmospheric retention
for lead particulates.

6.   Atmospheric Residence Time for Lead

The surface area of the earth is 5xl08 km2.  If we assume an equivalent atmospheric


depth of 2000 meters, the volume is 109 km3 or 1018 m3.  The total lead content
of the atmosphere is 2.0x10 ^ gm, assuming a concentration of 0.02 yg/m .  This
is equal to 20,000 metric tons.  As mentioned above, Goldberg and Gross (1971)
have estimated the global yearly release of lead into the atmosphere to be
610,000 tons.  Thus, the atmospheric retention factor is on the order of 3.3xlO~2.
From the retention factor, we have estimated the mean residence time of lead in
the atmosphere to be on the order of 12 days.  Other published results have shown
lead residence time to be 7-30 days (LEAD, 1972).  Other studies using various
radioactive tracers have given lifetimes of particulates in the lower troposphere
ranging from six days to two or more weeks (SMIC, 1970).

7.   An Erroneous Estimation for the Residence Time

However, measurements of atmospheric lead concentrations over the Indian Ocean and
northern Asia (Egorov, et al., 1970), where the concentrations are expected to be
smallest on a worldwide basis, were extrapolated to the entire atmosphere by the
Academy of Sciences (1973) to obtain 500 tons in the earth's atmosphere.  This
leads to a. retention factor of 10"3, or a mean residence time of only 8 hours!
If the residence time is, indeed, as short as eight hours then the distance of
travel of air parcels from the lead source is quite short.  Measurements made as
far away as many times this eight-hour travel distance cannot possibly be used
to estimate the mean global value.

8.   Analogy to Atmospheric Particulates

If the conservative retainment factor of 0.033 is applied to total global particu-
lates production, we have about 5xl07 tons of particulates in the atmosphere at
present.  Since 40% or more of this is due to man-related activities, 2xl07 tons
of atmospheric particulates may be controlled.  According to Barrett (1971), an
increase of 2xl06 metric tons of atmospheric particulates is capable of lowering
the mean annual global temperature of 0.4°C. Thus, man's activities are adequate
to account for the hemisphere's cooling since 1940.

9.   Worldwide Distribution of Locally-Emitted Particulates

It has been shown that dust emitted from various geographic areas can easily be
distributed globally (Jackson, et al.,  1973).  Circumglobal transport of aerosolic
dust was traced through radioactive debris, biological material, filtration of
air, and oxygen isotope abundance measurements in quartz isolated from dust and
from soils sediments having dust origin.   A strong momentum source is supplied by
large-scale cyclonic storms, where descending air enters the mixed volume, pro-
ducing gusts of strong wind at the ground.  Vertical fluxes of soil material
during dust storms reach the order of 10 ygcm~2 sec"1.  The general circulation
moves the dusty air with great speed thfoughout the entire hemisphere (Carlson
and Prospero, 1974).

10.  Evidence for Global Movement of Local Particulate Matter

Much information has been accumulated in recent years that shows that particulate
matter emitted locally into the atmosphere can easily be distributed over global
distances.   Geosynchronous satellite images have shown that particulate matter
from slash-and-burn agriculture in Central America can be dispersed over thousands
of kilometers (McLellan, 1972, 1973).   Carlson and Prospero (1974) have documented
particulate matter over the Caribbean for the last five years.   The source of
this material is the African continent.   Hot desert winds blowing across the


grassland of the sub-Sahara have been picking up large quantities of soil and
distributing it across the Equatorial Atlantic.  As a result of increased de-
flation of soil material during the severe drought of the last seven years, skies
over Barbados and other Caribbean isles have become as hazy as the air over
urban areas of the United States.  Measurements of dust at Barbados rose from
6 pg/m3 in 1966, to 8 pg/m3 in 1968, to 15 yg/m3 in 1972, to 24 pg/m3 in 1973.
Their measurements suggest that the threefold increase in dustiness since the start
of the African drought has contributed to a 10-15% reduction in solar energy
reaching the sea surface in the tropical Atlantic.

11.   Dynamical Means of Worldwide Particulate Loading

The mechanism of transport of the Saharan dust is similar to the transport of dust
from other large arid regions.  The transport occurs in large-scale pulses which
take several days to move 3 to 4 thousand kilometers.  Before each pulse reaches
the coastline, the air is subjected to prolonged, intense heating, which causes
strong mixing in an air layer which may be 15,000 to 20,000 feet deep in summer.
As this hot, dusty air emerges from the continent's coast, it is undercut by
relatively cool, moist winds which confine the polluted air to altitudes above
4,000 to 6,000 feet.  Over the ocean, the warm, polluted air becomes sandwiched
between the low level moist air below and the 15,000 to 20,000 foot level, which
corresponds to the top of the mixing layer over the arid land.  In this manner
the dust travels over oceans above the moist layers in which cloud and shower
activities do effective scavenging.  In this manner, dust emitted into the
atmosphere from local sources can be distributed worldwide.


It is well known that the climate of the world is different now from what it was
during the Pleistocene "Ice Age."  A number of researchers have investiaged the
fluctuations of the energy budget during the post-glacial period.  During this
century there have been a number of papers which dealt with the climate change
that started in the nineteenth century, and a few reports dealing with the re-
versal of the trend since 1940 to 1950.  Some of these will be discussed here.

The fact of changes in the earth's energy budget in the past is well known, but
the magnitude and causes of the changes are less well documented and understood.
For the last century there are sufficient data to make some moderately reliable
estimates of the climate change and some cruder estimates of causal factors.


The past 2,000 years is not only a period for which we have a great deal of infor-
mation, but also it is one of the distinct climatic episodes within the Holocene.
However, over this long a period, the time resolution of the data is too coarse
for us to explore the question of climatic change on the decadal scale.  On the
other hand, Bergthorson  (1962) has reconstructed the decadal mean annual tempera-
ture for Iceland over the past 1000 years from the historic records of the
duration and extent of sea ice on the Icelandic shore.  He calibrated the ice
record against the observed climatic data for the past 150 years.  A regression
equation was derived that provides a decadal temperature plot for the past
millennium (see Figure 4).   It is sometimes thought that the climate during
the period from 1931 to 1960 was a "normal" climatic period; however, Figure 5
puts this recent period into historical perspective.  There has been nothing like
it in the past 1000 years.


+ 0.8
UJ *°'4
i- -0.8



























^ 1



                                     YEAR, A. D.

            Figure  5.   Mean annual  temperature in Iceland  over  the  past
                       millennium (after  Bergthorson,  1962).  The dashed
                       line indicates  the rate of temperature decline  in
                       the  period 1961 to 1971.


 Other historical work  has  been  done by Lysgaard (1949).   He presented overlapping
 thirty-year mean temperatures for  Copenhagen  for the  period of 1798 through
 1947.  Two trends  appear to have prevailed:   downward by  about 0.8°C  until the
 1860's,  then upward by about 1.1°C to  1947.   Other  local  records,  such as those
 at Vienna,  Winnipeg, Edinburgh,  and Central England,  in general, also show the
 warming  trend  from the late 1800's to  about the middle of the present century.
 In the last two or three decades,  however, the  trend  seems to have been reversed
 (Lamb, 1966).  This trend  reversal, this  current cooling  trend, is of concern

 Mitchell  (1961) summarized many  records  from  a worldwide array to  show that the
 mean  temperature of the earth rose until  1940,  then leveled off and started to
 decline.   It appears that  the decline  has continued to the present time.  Of
 course, not all individual records show  the decline, but a rapid cooling appears
 in the overall average, so  that  the mean  temperature approaches that  of a century
 ago.  Thus, from an historical standpoint the recent drop in the earth's mean
 atmospheric temperature at  the surface is quite  rapid and quite large, and there
 are no signs that  the  trend is abating.  The surface temperature of the North
Atlantic Ocean has also dropped  (Rodewald, 1973).



We have estimated that 40% or more of the earth's atmospheric particulate load-
ing is due directly or indirectly to man's activities.  Since population growth,
mechanization, and industrialization are still under way in large parts of the
world, and if we attribute a large portion of the recent increase in atmospheric
turbidity to human activities, it appears that there is little that any one
nation can do alone to reverse the trend globally.  Nevertheless, if the analysis
and order of magnitude estimations in this paper are correct, it indicates that
we should study the problem much more intensively than we have done to date.
Man, even in modern industrial cultures, is too vulnerable to environmental changes
to ignore even what may appear at first glance to be trivial problems.

The world community is presently short of resources for the production of energy.
If nations find it in their interest to invest heavily in expanding large-scale
strip mining operations for coal, phosphate, oil shale or other resources in
semi-arid regions, it is quite important that thorough investigations be carried
out of the effects of these operations on the future trend of atmospheric parti-
culate loading.  Any analysis of the magnitude of the rock handling operations
of these large operations, such as the western U.S., oil shale will produce many
cubic miles of finely pulverized material.  Even a small fraction of this material
entering the atmosphere as fugitive dust cannot be ignored.

Changes in mean temperatures, in temperature extremes, in precipitation, in the
length of the growing season, or in intensity of sunlight reaching the earth's
surface, can lead to widespread modifications in the distributions and survival-
patterns of plants and animals.  If these changes occur over large or heavily-
populated areas, as appears to be happening in Northern Africa, their effects
can be enormous, as they affect the global patterns of the non-human biota and
the food supply of man.


There are a number of areas where further investigation can yield results toward
obtaining better estimates of particulate components.  A search for other meaning-
ful atmospheric trace constituents that parallel particulate emissions and concen-
trations should be begun.  Known trace constituents should be explored that are
indicative of man's activities, such as DDT, and those that are indicative of
natural causes in certain geographic areas of the world.  It is known that there
is DDT concentration of the order of 10-100 ppb within the African dust over
Barbados (Risebrough, et al., 1968; Risebrough, 1974).  It is known that there is
60 ppm of DDT concentration in the dust from India as it moves out over the
Indian Ocean  (Goldberg, 1974).  An investigation into the use of DDT in these two
regions, and the extent of agriculture, may provide one with a handle on the
relationship of man-induced and naturally-induced partlculates.

Plume and dispersion models for the larger urban regions should be developed to
account for the trajectories that cover thousands of kilometers.  It is well
known that the classical gaussian plume models fail when extrapolated over very
large distances, yet these models are still used for description of global dis-
persions.  These models can be enhanced by the use of synoptic weather maps, satel-
lite images and data from various ground based sampling stations.  Intense local
pollution over urban areas and industrial regions often travels over hundreds and
thousands of kilometers downstream without large horizontal dispersion and apparently
is carried along isotropic surfaces into the stratosphere.  The modeling of large-
scale dispersions of plumes into the stratosphere should be carried out.

 It is not yet  known how often  or  how  quickly  the  long distance transport of
 polluted air masses leads  to rainy  areas.  How long does it take for these air
 masses to reach remote  areas,  such  as Mauna Loa,  Hawaii, or Point Barrow, Alaska?

 Lettau and Lettau (1964) devised  a  general expression for the intensity of parti-
 culate fallout in the absence  of  rain based on time variations of beta-activity
 in surface air, due to  worldwide  tropospheric distribution of debris from nuclear
 testings.  They estimated  that the  average residence time of debris in the
 troposphere to be 65 days  if the  only cleansing process were dry-fallout.  Work
 along these lines using other  trace constituents  should be investigated.

 It is also critical that the significant  injections of stratospheric particu-
 late material  by jet aircraft  selectively over the U.S.-Atlantic-European
 Sector be explored with General Circulation Models.


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                                 TECHNICAL REPORT DATA
                          (Please read /asiructions on the reverse before completing)
                                                       3. RECIPIENT'S ACCESSION-NO.
 Changes in the Global Energy Balance
                                 5. REPORT DATE
                                  October 1974
                                                       6. PERFORMING ORGANIZATION CODE
                McLellanj TV } Tjniv of Wisconsin
 1125 West Dayton St. , Madison,  Wisconsin  53706
                                                       8. PERFORMING ORGANIZATION REPORT NO
The M.W. Kellogg Co.
1300 Three Greenway Plaza East
Houston, Texas  77046
                                 10. PROGRAM ELEMENT NO.
                                 1AB012; ROAP 21ADE-010
                                 11. CONTRACT/GRANT NO.

                                 68-02-1308 (Task 29)

 EPA,  Office of Research and Development
 NERC-RTP, Control Systems Laboratory
 Research Triangle Park, NC 27711
                                 13. TYPE OF REPORT AND PERIOD COVERED
                                 Final: 6/15-10/15/74	
                                 14. SPONSORING AGENCY CODE
          The report gives results of a study to determine the effect of aerosols on
 the earth's climate. There is much evidence that the earth's climate has undergone
 a wide variety of fluctuations. Over the past hundred millenia,  as the earth's surface
 temperature has decreased, volcanic dust in the atmosphere has increased (and vice
 versa). The report estimates that at least 40% of today's atmospheric particulate
 loading is due to man-made or man-accentuated sources. For the past 30 years,
 although the earth's annual mean temperature has been decreasing, volcanic activity
 has not been increasing.  Carbon dioxide and waste heat production have been incr-
 easing, but these processes tend to increase the global temperature rather than to
 reduce it. Man's production of particulates in the past 30 years has been increasing
 at a rapid rate. It is estimated that the loading rate of particulates  from commercial
 jet aircraft into the stratosphere, where the residence time is much longer than in
 the troposphere, is almost half  of that due to volcanic activity.  The study recom-
 mends that studies should be carried  out to obtain better data for more meaningful
 estimates for the sources and sinks of atmospheric particulates.
                             KEY WORDS AND DOCUMENT ANALYSIS
                                          b.lDENTIFIERS/OPEN ENDED TERMS
                                             c. COSATI Field/Group
 Air Pollution
 Earth Atmosphere
 Volcanic Ejecta
 Carbon Dioxide
Heat Transfer
Jet Aircraft
Air Pollution Control
Global Energy Balance
13B, 20M
07D, QIC
                                           19. SECURITY CLASS (ThisReport)
                                             21. NO. OF PAGES

                                                  27 '
                     20. SECURITY CLASS (Thispage)
                                                                   22. PRICE
EPA Form 2220-1 (9-73)