Science, and transportation united states senate

effects of applied weather modification technology could be of serious

importance and were yet but largely a matter of speculation. In that

year, the ad hoc weather working group of the ecological study commit-

tee of the Ecological Society of America published its report on bio-

logical aspects of weather modification which it had submitted to the

National Science Foundation's Special Commission for Weather Modi-

fication. 3 The report of the NSF Special Commission, also published

in 19G6, noted that "from the present crude state of the field, one can

roughly predict that the biological outcomes of weather modification

are apt to be a mixed bag of economically good and bad effects in man's

artificial ecosystems. It is difficult to visualize any desirable effect on

the small preserves of natural communities. 4 The Commission advised:

It is the position of the Commission that there should be a strong effort to bring

the field of biological forecasting up to a higher level of usefulness. This is inan-

2 Edward J. Kormondy, Concepts of Ecology, 2d ed., Englewood Cliffs, N.J. : Prentice-

Hall. 1976. pp. 1-2.

3 D. A. Livingstone, biological aspects of weather modification, a report from the Ecolo-

gical Society of America's ad hoc w eather working ^roup of the ecological study committee

to the Special Commission for Weather -Modification of the National Science Foundation

Bull. Ecol. Soc. Amer. 47 (196G) : 39-78.

4 National Science Foundation, weather and climate modification, report of the Special

Commission on Weather Modification, Washington, D.C., National Science Foundation. 19G6,

p. 19.

datory in planning weather and climate modification over areas involving more

than a few hundred square miles. 5

This and other related recommendations of the NSF Special Com-

mission directly or indirectly led to a number of ecological studies

which have been specifically concerned with identifying and predicting

ecological effects of weather modification.

One of the first sponsored studies was the problem analysis conducted

by Cooper and Jolly 6 for the Bureau of Reclamation, as that agency

began to better balance operational weather modification research with

studies aimed at understanding ecological, legal, economic, and other

social effects of weather modification activity. The report included

"sections on anticipated kinds of weather modification ; effects in semi-

arid climates and in humid climates ; pests and diseases ; direct effects

of seeding agents; biology of lakes and streams: fog, hail, lightning,

and hurricane modification ; environmental monitoring programs ; in-

ferences from ecological theory; recommended research; and recom-

mended premodification field surveys." 7

An extensive bibliography of relevant literature was also included.

Cooper, whose 1967 paper on the effects of weather modification on

plant and animal communities represented one of the earliest attempts

to anticipate ecological ramifications of the seriously developing

weather modification technology, 8 has continued to publish on the

subject. 9

Other major studies of note include work on the impacts of snow en-

hancement supported by the National Science Foundation, 10 and the

Bureau of Reclamation, 11 and on impacts and issues associated with

efforts to suppress hail. 12 Also of importance and interest, of course,

are the proceedings of the several conferences on weather modification

which have been sponsored biennially since 1968 by the American

Meteorological Society. Papers on environmental considerations and

impacts associated with weather modification efforts and technologies

5 Ibid., p. 20.

6 Cooper anrl Jolly, ecological effects of weather modification, 160 pp. (Note 1.)

7 Ibid., p. 160.

s C[harlesl F. Cooper, effects of weather modification on plant and animal communities.

Taper presented at Symposium on Weather Modification, AAAS Committee on Arid Lands,

New York. Dec. HO. 1067 (mimeo).

6 Charles F. Cooper, ecological impacts of local and global weather modification, paper

prepared for Hist annual meeting, American Meteorological Society, San Francisco, Jan. 14,

1971. 16 pp. (mimeo).

Charles F. Cooper, ecological implications of weather modification, paper prepared for

the Weather Modification Advisory Board, U.S. Department of Commerce, 1977, 19 pp.

(mimeo).

Charles F. Cooper, what might man-induced climate change mean? Foreign Afrairs 56(3)

(1978) : 500-520.

Charles F. Cooper, Georsre W. Cox. and Warren A. Johnson, investisations recommended

for assessing the environmental impact of snow augmentation in the Sierra Nevada. Calif.,

prepared for tbe Bureau of Reclamation and the California Department of Water Resources,

San Diego : San Diego State University. Center for Regional Environmental Studies, 1974,

84 pp.

10 Leo W. Weisbecker fcorap.). The impacts of snow enhancement, contract report pre-

624 pn.

tation in the San Juan Mountains. Colorado. Final report of the San Juan ecological project

to the Bureau of Reclamation. 25 papers. 1976. 489 pp.

22 Stanley A. Changnon, et al.. Hail suppression, impacts and issues. Final report, tech-

nology assessment of the suppression of hail. Office of Exploratorv Research and Problem

Assessment. RANK program, National Science Foundation. Urbana, 111. : State Water Sur-

rey, 1977, 432 pp.

490

Environmental Statement for Project Sky water, published in 1977 by

the Bureau of Eeclamation, consists of a three- volume statement cover-

ing the post- 1964 research program of the Bureau relating to the ef-

fects that cloud seeding for increasing growing season precipitation

and mountain snowpacks might have if the technology were applied

over long periods of time. 14 One of the appendix reports attached to the

statement reviews research relating to environmental effects of seeding

agents, particularly silver iodide. The question of the effects of silver

iodide on the environment, particularly over time, has also been ad-

dressed and reported on in other publications. 15 The definitive review

to date of the subject of environmental effects of nucleating agents,

based on a 1976 workshop, has recently been prepared by Klein ia

under National Science Foundation sponsorship.

Thus in the 12 years since the National Science Foundation's Spe-

cial Commission on Weather Modification issued its report, a sig-

nificant volume of research aimed at determining and evaluating

possible ecological effects of weather modification has been under-

taken. In summarizing the results and inferences from Project Sky-

water which relate to environmental impacts, Howell tabulates 11

individual contracts for environmental research sponsored by Project

Sky water. 17 They cover the 1964-76 period and total nearly $3

million.

Some of the more specific findings and conclusions of the research

efforts cited above are extracted and summarized under the various

topical headings which follow.

Important Variables

As Cooper has noted, "Weather modification is by definition a

change in the natural climatic environment.*' 18 He continues : "It is

impossible to predict 'the ecological effects of weather modification.*

A specific expected alteration in the natural weather pattern must first

be defined. Usually this can be done only within probability limits.

Unless the expected change in climatic input to the ecosystem is known,

no reasonable predictions can be made. Seldom has sufficient infornia-

13 See : Proe., First National Conference on Weather Modification of the American Mete-

orological Society, April 28-May 1, 1968, State University of New York at Albany : 173-

ISO. Boston : Amor. Meteor. Soc. ;

Proc, Second National Conference on Weather Modification of the American Meteorolog-

ical Society, April 6-9, 1970, Santa Barbara, Calif. : 411-414. Boston : Amer. Meteor. Soc. ;

Proc, Third Conference on Weather Modification of the American Meteorological Society,

June 26-20, 1972. Rapid City, S. Dak. : 226-231. Boston : Amer. Meteor. Soc. ;

Proc, Fourth Conference on Weather Modification of American Meteorological Society,

Nov. 18-21, 1974. Fort Lauderdale, Fla. : 502-334. Boston : Amer. Meteor. Soc.

14 Bureau of Reclamation, Final environmental statement for Project Skywater. Denver:

Bureau of Reclamation Engineering and Research Division, 1977, 340 pp. (vol. 1) plus

appendices (vols, 2, 3).

15 Charles F. Cooper and William C Jolly. Ecological effects of silver Iodide and other

weather modification agents: a review. Water Resources Research 6 (1) (1970) : 88-98i

D. A. Klein. Ecological impacts of nucleating agents used in weather modification prosrrams :

an interdisciplinary assessment, J. Weather Mod. 9(4) (1977) : 51-56; Ivan C Smith and

Ronnie L. Carson. Trace Metals In the Environment: Vol. 2. Silver, Ann Arbor, Mich. : Ann

Arbor Science Publishers. 1977, 490 pp.

19 D. A. Klein fed.), Environmental impacts of nucleating agents used In weather modi-

fication. StrOudsberg, Pa. : Dowden, Hutchison and Ross. 1978.

"Wallace E. Howell, Environmental Impacts of precipitation management: results and.

Inferences from Project Skywater. Bull. Amer. Meteor. Soc. 58(6) (1977) : 489.

18 Cooper, Ecological implications of weather modification, p. 1 (Note 9).

491

would make ecological assessments." 19 It may be useful to mention

a number of the variables which must be considered before one can

attempt to predict the ecological impact of a given weather modifica-

tion. These variables are treated more completely by, inter alia, Cooper

and Jolly, 20 and by Cooper. 21

TEMPORAL CONSIDERATIONS

Season of modification effort

Within a given ecosystem reactions of vegetation and associated

animal communities to an expected 5-percent to 10-percent increase

in mean precipitation during years of normal or subnormal precipita-

tion will vary, for example, depending on whether that increase falls

during a dormant or a growing season, or whether the increase comes

in the form of rain or snow. Whether there are impacts such as im-

pedance to physical movement (as with deep snow and deer), or

threats to nesting and newborn survival (as with heavy, cold rains

which can affect incubating ducks or newly hatched pheasant chicks),

may also be of importance. Similarly, if a plant community were sub-

ject to moisture stress and precipitation enhancement measures pro-

duced timely relief, the impact would be different than if the plants

had reached a point of no return in their response to moisture depriva-

tion. Thus, the season at which a given effect is achieved may be of

prime importance.

Duration of effort : Short-term versus long-term

Biological communities evolve and exist under terms of natural

variability in weather and climate. The kinds of reactions of such

communities to weather modifications of limited duration will be quite

different from those when a given modification recurs with some regu-

larity over time. Pest or disease outbreaks may be triggered by a par-

ticular change of critical timing in a moisture regime, for example,

but changes in species composition in ecosystems will normally require

at the very least more than one season of change in precipitation

pattern, and often several seasons are necessary.

Regularity of modification effort

Just as the duration of effected changes in weather pattern, both in

terms of days or weeks in a given season and of weeks, months, or sea-

sons of a given year, is significant, so is the regularity with which a

given change is produced. Biological communities will react one way if

a 10-percent increase in mean precipitation is realized on an annual

basis but the timing and distribution of that increase is rather variable

over the year and from year to year. The response may well be dif-

ferent if the increase occurs with some fidelity at a given season (or

seasons), from one year to the next — especially if the time of such

change is coincident with a particularly critical time in the life cycle

of an organism or a community.

19 Ibid., p. 3.

» Cooper and Jolly, Ecological effects of weather modification (Note 6).

n Cooper, Ecological implications of weather modification (Note 9).

492

ECOSYSTEM TYPE

modification program will also differ depending on the class of ecosys-

tem being affected. A few dichotomies will illustrate the point.

Aquatic versus terrestrial systems

Organisms in aquatic systems are affected by such variables as tur-

bidity, temperature, stream velocities, periods and durations of low

flows, and the chemical quality of the water, including relative levels

of dissolved oxygen. Terrestrial organisms are affected by the timing,

amount, and continued availability of both soil and surface moisture,

and by the form (water, snow, ice) which such moisture may take.

The same level of enhanced (or reduced) precipitation in a given area,

therefore, will have different significance and meaning for terrestrial

than it will for aquatic components. It is necessary to distinguish be-

tween systems being affected at this gross level as well as at finer levels

of detail, too.

Cultivated versus natural systems

Howell has observed that :

Over most of the civilized world, the natural environment is profoundly accul-

turated and bears few traits of wilderness. In considering the natural environ-

ment, one must, therefore, regard the environment as it is exemplified by the real

landscape. Except for a few pockets of wilderness, the environment is the prod-

uct of an ongoing symbiosis between the land and humankind [attributed by

Howell to Dubos]. It is, nevertheless, useful to make the distinction between the

direct, intentional impact of precipitation management on a cultural element

such as agriculture and the complex of indirect effects that may impinge on other

elements of the landscape and biosphere, be these "natural" or cultivated*

Cooper, in treating these two classes of ecosystems, says :

As a rule of thumb, the more intensively managed a tract of landscape, and the

farther it is from its natural ecological condition, the less its species structure is

dependent upon the detail of the local environment and the less sensitive it will

be to minor climatic alteration. 23

Because species composition, population structure, growth rate, and

behavior of plants and animals in noncultivated ecosystems are sig-

nificantly different from those attributes of cultivated systems, the

effects of any given modification of weather are likely to be signifi-

cantly different as well.

Arid versus liumid systems

As one would expect, a given relative change in mean precipitation

in more arid systems would be more likely to result, over time, in not

only changes in relative species composition, but possibly changes in

vegetative forms (e.g., shrub to grass) than would changes in humid

ecosystems. The signal to noise ratio is likely to be stronger in the more

arid situation and the response would be ecologically less subtle.

CUMULATIVE AXD SYNERGISTIC EFFECTS

Finally, the obvious must be stated, as Cooper and Jolly did earlier : 24

Ecological effects of weather modification will be the result of moderate shifts in

rates of reproduction, growth, and mortality of weather-sensitive species of plants

- Howell. Environmental Impacts of precipitation management: results and inferences

from Project Sky water, p. 493 (Note 17).

::t Cooper. Ecological implications of weather modification, pp. 6-7 (Note 9).

24 Cooper and Jolly, Ecological effects of weather modification : a problem analysis, p. 2

(Note 1).

493

; and animals. Ecological changes from the kinds of weather modification now

ties change rather slowly in response to changed climate. The cumulative effect

of slow year-to-year changes in species abundance could be a rather extensive

[ alteration of original condition, but the alteration could take place almost un-

noticed by the general public.

The combined effect of such stresses as air pollution, pesticide application, and

other environmental changes may interact with weather modification in such a

way that the total effect will be substantially greater than the sum of the individ-

ual, perhaps relatively small, alterations.

Effects of Silver Iodide

Nearly all current weather modification efforts depend on the use of

seeding agents to alter the microphysical processes within clouds.

While silver iodide has been the principal nucleating agent to date, it is

not the only such agent. It could be replaced in the future because of the

relatively high cost of silver and demands that widespread application

of silver iodide might place on the silver market. The advantages of

silver iodide with respect to substitutes are its capability of inducing

ice crystal formation at relatively high temperatures, the ease with

which it can be finely divided and carried in updrafts to cloud bases,

and the relatively small amounts required to initiate nucleation. Ten

to 1,000 times the weight of other substances is required to produce the

same quantities of ice crystals. 25 Other seeding agents which have been

used or whose potential use has been investigated include dry ice, lead

iodide, common salt, liquid propane, water spray, and a number of

organic compounds. Some of these seeding agents are substitutes for

• silver iodide, while others are intended for increasing precipitation

from warm cloud systems or dispersal of warm fogs through the co-

alescence process, where silver iodide would not be effective. Since the

use of silver iodide in weather modification experiments and opera-

tions has been so widespread, the following discussion is limited to the

potential for environmental impacts from that compound.

Cooper and Jolly reported that available evidence shows little likeli-

hood of environmental effects from the iodine in silver iodide. They

cited a calculation made in an early report that :

A human consumer would have to drink 130 gallons of precipitation from a

storm seeded with silver iodide to obtain as much iodide as in eggs flavored with

iodized table salt and concluded that iodide is ubiquitous in organic and inor-

ganic environments. ... It seems reasonable, therefore, to dismiss iodine in

silver iodide at present levels of use as a source of ecological concern. 26

u Particular concern is. therefore, for the effects of concentrations of

silver in the soil and aquatic systems, and it should be recognized that

weather modification is only one avenue by which silver compounds

can enter these systems.

Silver is a paradoxical substance: it is potent as a microbial poison,

but relatively harmless to higher animals and to man. It forms many

different chemical compounds which differ in their biological activity,

23 Bonnie L. Carson and Ivan C. Smith. Silver : an appraisal of environmental exposure.

Technical Report No. 3, for National Institute of Environmental Health Sciences. Contmet

I No. N01-ES-2-2090. Midwest Research Institute, Kansas City. Mo.. July 16, 1975. p. 221.

, 23 Cooper and Jollv. Ecological effects of weather modification, p. 64 (Note 1).

Cooper and Jolly, Ecological effects of weather modification agents : a review, p. 89 (Note

15).

494

Silver is unique among metals in combining very low solubility of

most of its compounds with high toxicity of the soluble fraction, with

the result that it is substantially more harmful to microorganisms than

it is to higher animals and plants. 27 Silver, even in its highly soluble

form, is only moderately harmful to mammals, but is much more toxic

to fish than to terrestrial vertebrates, and silver levels required to

damage higher plants are many times greater than those which would

occur in precipitation from seeded storms. Because most land plants do

not actively take up silver, the likelihood of concentrating the metal

through terrestrial food chains is small, both immediately and over a

period of perhaps 20 years. 28 It was pointed out, however, that con-

tinuous reassessment during such a period of application should be

made with the accumulation of new information. 29

In 1974, Klein and Molise summarized results of their study of two

Colorado weather modification projects :

In summary, the silver levels found in soil, litter, and vegetation samples in two

Colorado weather modification projects appear to be at least one to two orders of

magnitude below where possible interactions between accumulated silver iodide

and changes in decomposer functions have been observed in our studies to date.

The trend toward silver concentration in the vicinity of plant roots suggests that

localized higher concentrations may occur which could be of distinct ecological

interest. 30

Recently, based on studies supported by Project Skywater, Howell

estimated the relative quantities of total silver in various environ-

mental compartments for the contiguous United States.

The soil compartment (including also mud and vegetable litter), calculated for

the top 20cm comprising the root zone, contains by far the largest quantity of

silver. . . . Living matter of all sorts from microbes and fungi to animals, which

has on the average a slight tendency to concentrate silver from the soil, contains