Science, and transportation united states senate

Not. 17-22, 1975 ; Ottawa, Science Council of Canada, 1976, p. 88.

71 Hobbs, P. V., H. Harrison, and E. Robinson, "Atmospheric Effects of Pollutants," pp.

910, 911.

72 The atmosphere is principally heated by terrestrial reradiation, thus the reflected

incoming light, escaping back into space instead of being transformed into heat, represents

a deficit in the Earth's energy balance.

180

in October 1972 as in October 1968 and correlated that situation with

a drop in global air temperatures. They warned that the potential

for fast changes of climate evidently does exist and should be kepfe

in mind. 73

There's yet another contributor to the planet's albedo : airborne par-

ticles, particularly the extremely fine dust particles that have been

carried too high in the atmosphere to be scavenged and washed out

by precipitation processes. Many of these particles remain aloft for

months or years. Dust of various kinds may initiate short-term cool-

ing trends with characteristic time spans of decades or centuries. This

depends on the optical properties of the particles, which in turn de-

pend on particle composition and size distribution. Furthermore, par-

ticles radiate in the infrared, and therefore can alter the outgoing

long-wave radiation.

Densely populated regions tend to have higher albedos than do

forests or cultivated soils. The deserts of the world have a highei

albedo than, for example, grass-covered fields. Urbanization, agricul-

ture, transportation networks — all act to alter the surface albedo.

While local changes in albedo have been determined, however, the

overall integrated global variation is still unknown. Even local net

effects of surface changes may not be fully understood, since changes

in the nature of a surface are generally accompanied by change in

surface roughness. Surface roughness alterations can affect the man-

ner and rate of heat and momentum exchanges with the atmosphere

through modification of small-scale turbulent processes. 74

A factor such as roughness of the ocean should not be overlooked

in ocean/atmosphere exchange mechanisms. Ocean surface pollution

may also figure in the alteration of the albedo as well as the sea surface

characteristics: an oil slick forming a surface film on the sea. for

example.

LARGE-SCALE IRRIGATION"

Beginning in the 1940's, large areas of the Texas Panhandle, western

Oklahoma, Kansas, and Nebraska came under widespread irrigation.

This large-scale irrigation adds more moisture to the air through

evaporation; has made large land surfaces greener (which changes

the albedo) ; and may act to decrease dust in the air. Since the situation

is somewhat analogous to a large-area rain modification project, a

number of studies have been conducted to ascertain if greater rainfall

could occur in the vicinity or downwind of irrigated areas.

Schickedanz (1976) provided strong evidence of irrigation-related

anomalies; specifically, increased rainfall during months when irri-

gation took place in and/or surrounding large irrigated areas of the

Groat Plains.

The percent rain increase associated with the irrigation effect was

found to vary from 14 percent to 26 percent in June, 57 percent to

91 percent in July, 15 percent to 26 percent in August, and 19 percent

73 Kukla, George .T., and Helena J. Kukla, "Increased Surface Albedo in the Northern

Hemisphere," Science, vol. 183, Feb. 22, 1974, pp. 709, 713, 714.

A growing fraction of current evidence seems to suggest, however, that this has not been

the in North America. Analysis of satellite data for the last decade has led scientists

with the National Environmental Satellite Service to conclude that North American anow

cover showed no significant change during the entire period of record. Rather, the North

American total winter snow cover appears to be remarkably similar year to year. Eurasion

snow cover on the other hand was reported to be much more variable.

w National Research Council, Committee on Atmospheric Sciences, "Weather and

Climate Modification : Problems and Progress," p. 156.

181

the irrigated areas in the States of Kansas, Nebraska, Oklahoma, and

Texas.

Acting similarly to the manner in which urban industrial centers

to be a focal point for both rain initiation and rain enhancement or

redistribution, under conditions when rain is likely. 75 ' 76

Stick! (1975) also found evidence of irrigation-related rainfall

, anomalies in the Columbia Basin of Washington. Explaining that the

increase in rainfall is real, he offered the following explanation :

The moisture added by irrigation is evaporated and must eventually return

I to the Earth's surface as precipitation. The question is where and when? The

[Columbia] basin is nearly surrounded by mountains. The surface layer of air

in the basin will eventually be carried over the mountains [at the eastern margin

of the basin], and if additional moisture has been added to the air * * * air, we

would expect additional precipitation in the foothills. This appears to be what

happens during the two months [of July and August] when additional evapora-

tion is greatest. 77

RECAPITULATION*

In review, tables 2, 3, and 4 summarize much of the pertinent infor-

mation presented in the preceding sections. They are, respectively,

"Inadvertent Effects on Ten Weather Phenomena," "Chronic Low-

Level Pollutants : Mankind's Leverage Points on Climate," and "Pos-

sible Causal Factors in Future Climatic Change to the Year 2000 A.D."

TABLE 2. — INADVERTENT EFFECTS ON 10 WEATHER PHENOMENA 1

Importance/signifi-

Certainty of inad- Scale of inadvertent cance of inadvert-

Phenomenon vertent effect effect ent effect

1. Visibility and haze

Certain.

Meso

Major.

Macro

2. Solar radiation and sunshine

Certain

Meso

3. Cloudiness

....do

Urban

Probable

Meso

Do.

Certain

Major.

Meso or macro

Moderate.

Precipitation (quality)..

Certain

Urban

do

Unknown.

Possible

Macro

5. Thunderstorms (hail/heavy rain)

Certain.

Urban

Possible

Meso

Do.

Unknown

Unknown.

7. Temperature

Certain...

Urban

Moderate.

Populated meso

Minor.

8. Wind/circulation.

Moderate.

Unlikely

Meso

9. Fog

Major.

Moderate.

do

Meso

i From "Final Report to the National Science Foundation on the Third Inadvertent Weather Modification Workshop,'!

Hartford, Conn., May 23-27, 1977. Hartford. The Center for Environment and Man, Inc., 1977.

Note.— Micro: less than or equal to 1 km; urban: less than or equal to 30 km; meso: 30 to 150 km; macro: greater than

150 km.

75 Schickedanz, Paul T.. The Effect of Irrigation on Precipitation In the Great Plains.

Final report on an investigation of potential alterations in summer rainfall associated

with widespread irrigation in the Great Plains, Urbana, 111., Illinois State Water Survey,

1976. 105 pp.

76 Schickendanz, Paul T., "Extra-Area Effects from Inadvertent Weather Modification."

In preprints of Sixth Conference on Planned and Inadvertent Weather Modification,

Champaign-Urbana, 111., Oct. 10-13, 1977. Boston, American Meteorological Society,

1977, pp. 134-137.

"Stidd, Charles K., "Irrigation Increases Rainfall?" Science, vol. 188, Apr. 18, 1975,

pp. 279-281. In Effect of Large-Scale Irrigation on Climate in the Columbia Basin,

Science, vol. 184, Apr. 12, 1974, pp. 121-127. Fowler and Helvey argue that small scale

site changes may occur, but the widespread climatic effects of irrigation may well be

minimal. Furthermore, they contend that the available precipitation records for the

basin do not verify Stidd's conclusion that precipitation increased because of irrigation.

182

184

climatic barriers to long-term energy growth

Revelle and Suess (1957) stated:

Human beings are now carrying out a large scale geophysical experiment of

a kind that could not have happened in the past nor be repeated in the future.

Within a few centuries we are returning to the atmosphere and ocean the con-

centrated organic carbon stored in the sedimentary rocks over hundreds of mil-

lions of years. This experiment may yield a far-reaching insight into the processes

of determining weather and climate. 78

Thus stated is the case for diligent observation of the consequences

of the man-generated flux of carbon dioxide to the atmosphere. Left

unstated is perhaps the greater need to anticipate the consequences

well enough to keep them within acceptable limits.

Even though carbon dioxide makes up a small fraction (less than

one one-thousandth of the total atmospheric mass) of the gases that

comprise the atmosphere, it is crucial in determining the Earth's

temperature because it traps some of the Earth's heat to produce the

so-called greenhouse effect.

Worldwide industrial civilization may face a major decision over

the next few decades — whether to continue reliance on fossil fuels as

principal sources of energy or to invest the research and engineering

effort, and the capital, that will make it possible to substitute other

energy sources for fossil fuels within the next 50 years. The second

alternative presents many difficulties, but the possible climatic con-

sequences of reliance on fossil fuels for another one or two centuries

may be critical enough as to leave no other choice.

The climatic questions center around the increase in atmospheric

carbon dioxide that might result from continuing and increasing use

of fossil fuels. In 110 years since about 1860 a 12-percen.t increase in

the concentration of carbon dioxide had taken place, but because of

the exponential nature of the consumption of energy and the burning

of fossil fuels the next 10-12 percent increase would take only about

20 years and the next 10-12 percent increase beyond that only about

10 years. By this time the climatic impact of the carbon dioxide should

(according to model calculations) cause a climatic warming of about

1°C (1.8°F). Four questions are crucial :

1. What concentrations of carbon dioxide can be expected in the

atmosphere at different times in the future, for given rates of combus-

tion of fossil fuels ?

2. What climatic changes might result from increased atmospheric

carbon dioxide?

3. What would be the consequences of such climatic changes for

human societies and for the natural environment ?

4. "What, if any, countervailing human actions could diminish the

climatic changes or mitigate their consequences ? 79

Whether such a warming would influence the extent of ice and snow

at the polar caps or influence the level of the world ocean cannot be

■« Rpvelle R. and H. E. Suess, "Carbon Dioxide Exchange Between the Atmosphere

and Ocean,'' and the "Question of an Increase in Atmospheric Carbon Dioxide During

the Past Decades," Tellus. vol. 9, No. 1, 1957, p. 18. . „

n National Research Council, Geophysics Research Board, "Energy and Climare, p. 1.

185

would push the grain belts of the world poleward by several hundred

kilometers thereby disrupting the present patterns of agriculture.

These are possibilities, but climatic theory is yet too crude to be certain.

The only certain proof that the carbon dioxide-greenhouse theory is

correct will come when the atmosphere itself ''performs the experi-

ment" of proving present estimates too high, or too low. An important

point remains, though, and that is : The uncertainty in present scien-

tific estimates of potential climatic consequences of increased energy

use is not biased toward optimism. 80

Carbon dioxide is not the only byproduct of the burning of fossil

fuels. Another form of atmospheric pollution results from the intro-

duction of dust and smoke particles, which, when suspended in air. are

called atmospheric aerosols. The word "aerosols" is a term used to

describe the suspension of any kind of particle in a gas. These particles

can be solid like dust, sand. ice. and soot. Or they can be droplets like

the water particles in clouds and fog or the liquid chemicals that are

dispensed as droplets from aerosol spray cans. The air contains tril-

lions upon trillions of aerosol particles, which, like carbon dioxide,

comprise only a minute fraction of the total atmospheric mass.

Despite their relatively small volume, aerosols can affect the climate,

primarily by absorbing and scattering back to space some of the sun-

light that could have otherwise reached the Eartlrs surface. Industry

is not the only human activity that causes aerosols. They are also pro-

duced in great quantities by a variety of agricultural activities and

practices, and a significant fraction of the particle loading of the

atmosphere is of natural origin.

A consensus among scientists today would not be forthcoming as to

whether an increase in aerosols would result in a cooling of the climat < 3

or a warming of the climate, because aerosols will cool the climate if

they are relatively whiter than the surface over which they lie, or,

alternatively, they will warm the Earth if they are relatively darker

than the surface over which they are suspended. The dust that exists in

the atmosphere today is highly nonuniform in both geographic distri-

bution and relative brightness as compared to the underlying surface.

Therefore, one cannot be absolutely certain whether dust contributes

to climatic warming or can be implicated in climatic cooling. sl

THOUGHTS AND REFLECTIONS CAN WE CONTEMPLATE A

FOSSIL-FUEL-FREE WORLD?

Putting together the different parts of the story of climate and

energy, what picture emerges? How seriously do we respond to the

possibility that the present rate of increase of fossil fuel burning is

likely to have noticeable consequences for climate by the end of this

century, but not become a serious problem until well into the next

century? On the longer time scale, the picture that emerges is rather

startling in the words of Dr. Wallace Broecker of the Lamont-Doherty

Geological Observatory, who explains, "Consumption of the bulk of

the world's known fossil fuel reserves would plunge our planet into a

80 Schneider, Stephen H., "Climate Change and the World Predicament." Climatic

Change, vol. 1, No. 1, March 1977, pp. 31-33.

61 Ibid., pp. 34, 35.

186

the last million years." 82

Admittedly, we are talking here of possibilities, not certainties. The

climatic consequences of massive fossil fuel consumption may be less

severe than assessments project, but they might be more severe. Man-

kind eventually may discover a new energy source that will obviate the

need to use fossil reserves so extensively for that purpose, and yet a

fossil-fuel-free world in the relatively near future is so bizarre an idea

it is hard even to talk about it seriously. Or perhaps technology could

develop a cosmetic, such as the introduction of an artificial dust layer

surrounding the Earth to screen some of the incoming sunlight. This

could tend to offset the warming effect of the added carbon dioxide.

What would happen if society elected to ignore the problem of

carbon dioxide until it manifested itself (perhaps in another 20 years)

in the form of a clear signal that a global warming trend had begun

that was unmistakably attributable to the further accumulation of

carbon dioxide in the atmosphere? Delaying until then a mandated

action to phase over the principal energy sources from fossil fuels to

other alternative kinds of fuels and taking into account another

several decades for the transition to be completed would put us half-

way into the next century before the problem could be shut off at its

source. But perhaps the most disturbing aspect of the carbon dioxide

problem is that the effects of carbon dioxide would endure for hundreds

of years, even after the abandonment of the fossil fuel economy, because

of the long recovery time associated with the processes that would rid

the atmosphere of excess carbon dioxide and establish an equilibrium

condition.

This carbon dioxide Sword of Damocles, if indeed it exists, implies

development of solar (including wind, ocean, biomass, etc.) fisson,

fusion, and geothermal at a somewhat more rapid pace than is gen-

erally recognized. 83

Asserts J. Murray Mitchell, Jr. :

The alternative is clear. Ours is the generation that must come to grips with

the carbon dixoide problem and mount a vigorous research effort to allow us to

understand all of its ramifications for the future. Ours is the generation that may

have to act, and act courageously, to phase out our accustomed reliance on fossil

fuels before we have all the knowledge that we would like to have to feel that

such action is absolutely necessary. * * * We can scarcely afford to leave the

carbon dioxide problem to the next generation. 84

RESEARCH NEEDS AND DEFICIENCIES

Despite everything that science has learned about the broad charac-

teristics of climate and climatic history, relatively little is known of

the major processes of climatic change. Lack of knowledge still is a

82 Mitchell, J. Murray^ Jr., "Carbon Dioxide and Future Climate," p. 9.

83 Rotty, R. M. and A. M. Weinherg, "How Long Is Coal's Future," pp. o5-57.

M Mitchell, J. Murray, Jr., "Carbon Dioxide and Future Climate," p. 9.

187

major barrier to accurate forecasting and understanding of potential

the ocean make up such a complex and rapidly changing system that

even short-range forecasts may often be incorrect. Gathering sufficient

information about global climate is of importance if atmospheric

scientists are to construct the detailed computerized models capable of

rapidly analyzing enormous amounts of data concerning each com-

ponent of the climatic system, which includes not only the atmosphere

but the world ocean, the ice masses, and the exposed land surface.

Observations are essential to the development of an understanding

of climatic change. Without them, theories will remain theories and

models would be of limited usefulness. Observational records need to

be extended in both time and space to facilitate adequate documenta-

tion of the climatic events that have occurred in the past and monitor-

ing of the climatically important physical processes occurring now.

Knowledge of the mechanisms of climatic change may be at least as

fragmentary as the state of the data. Not only are the basic scientific

questions largely unanswered, but in many cases not even enough is

known to pose the key questions. What are the most important causes

of natural climatic variation, and which are the most important or

most sensitive of the many processes involved in the interaction of the

air, sea, ice, and land components of the climatic system ? There is no

doubt that the Earth's climates have changed in the past and will likely

change in the future. But will it be possible to recognize the first phases

of a truly significant climatic change when it does occur ?

In a 1975 report, "Understanding Climate Change : A Program for

Action/' the U.S. Committee for the Global Atmospheric Research

Program of the Xational Research Council enumerated the principal

approaches to these problems emphasizing the interdependence of the

major components of a climatic research program and posing a number

of key questions. The components included :

Climatic data analysis : What has happened in the past?

Empirical studies : How does the system work?

Monitoring : What is going on now ?

Numerical models: What is shown by climatic simulations?

Theoretical studies : How much do we really understand ?

Climatic impacts : What does it all mean to man ?

Future climates : How and when is the climate going to change ?

The various components of the climatic research program are to a

great extent interdependent : Data are needed to check general circula-

tion models and to calibrate the simpler models ; the models are needed

to test hypotheses and to project future climates : monitoring is needed

to check the projections ; and all are needed to assess the consequences. 85

85 National Research Council, U.S. Committee for the Global Atmospheric Research

Program. "Understanding Climatic Change : A Program for Action," Washington, National

Acadmy of Sciences, 1975, pp. 5, 6.

188

Effort Frequency

variable or index Method Coverage required • required 2

Atmospheric indices:

Solar constant Satellite Global N W

Absorbed radiation, albedo do do P W

Latent heating... ...do do. N W

Surface latent heat flux do World ocean N W

Surface sensible heat flux do Regional N W

Cloudiness do Global P W

Surface wind over ocean Radar scattering World ocean N W