Science, and transportation united states senate

the next largest quantity. The exchange between living matter and soil through

uptake and decomposition dominates all other exchanges by at least an order of

magnitude. . . . The silver concentration and content in lakes and rivers are

determined mainly by depositional and erosional exchanges with the soil and by

runoff to the sea. . . . The atmospheric domain receives silver in the form of wind-

blown dust, some of which returns to the soil . . . and some of which is swept up

by particles of precipitation. . . . The silver content of the atmospheric compart-

ment at any moment is small in comparison with the annual transport through it. 31

Table 1 shows the annual total losses of silver to the environment

from various sources, as compiled by Carson and Smith. 32 It should be

noted, in comparison with other sources of silver, that cloud seeding

contributes about 0.1 million troy ounces of silver annuallv, about 1

percent of the silver received by the atmosphere and one-tenth of 1 per-

cent of that entering the total environment.

Cooper and Tolly. "Ecological Effects of Weather Modification.'" pp. R4-65 (note 11.

Cooner nnd Jolly. "Ecological Effects of Silver Iodide and Other Weather Modification

Agents" : a review, p. SO (note 15).

- s Cooper and Jolly, "Ecological Effects of Weather Modification," pp. GG-70 (note 1).

20 Ibid., p. 70.

WD. A. Klein and E. M. Molise. Ecological ramifications of silver iodide nucleating acrent

accumulation in soil and aquatic environments. Proc, Eonrth conference on weather rnoiii-

of the American Meteorological Society, Nov. 18-21, 1974, Fort Lauderdale, Fla.,

P. 534-.

•'Howell. "Environmental Impacts of Precipitation Management": results and infer-

ence f;-oni Project Skywater. pp. 400 407 (note 17).

C irsoil and Smith, "An Appraisal of Environmental Exposure," pp. 403-406 (note 25).

495

TABLE 1.— ANNUAL LOSSES OF SILVER TO THE ENVIRONMENT FROM VARIOUS SOURCES

[In millions of troy ounces]

Loss category

Air

Water land

Land

Total

Cyanidation

Michigan Cu ore tailings

Other Cu ore tailings

Mo. Pb ore tailings

Mine drainage

Leaching of tailings

Blowing of tailings

Primary smelting and refining, total

Of copper

Of lead

Of zinc...

Of silver

Secondary smelting and refining, total

Of precious metal scrap.

Of copper scrap

Of lead scrap.

Fabrication, total..

Of sterling silver

Of medicinals and dental materials..

Of electroplate..

Of other coatings

Of silver compounds

Of photographic products

Brazing

Use and disposal, total...

Photography.

Brazing alloys.

Cloud seeding

Other uses

Urban refuse

Inadvertent sources, total

Iron production:

Sintering

Blast furnaces (5 percent scrap).

Steelmaking:

Open hearth furnaces (44 per-

cent scrap)

Basic oxygen furnaces (29 per-

cent scrap)

Electric arc furnaces (97 per-

cent scrap)

Iron foundries (—88 percent scrap).

Cement manufacture

Fossil fuels:

Petroleum (fuel oil plus gaso-

line)

Coal

0.042

1.2-1.3?

. 35-. 48

.07?

.7?

.0002

.0002

. 00025

. 00025

. 00015

.07

.1

.68

.03?

36-1.8?.

015? .

.40?

3.1?

1.24

.024

.47

.78

4. 2-4. 35

. 22-. 35

1.5

3. 2-7. 2

"\~65-.~16"

03

4.0

3 12.0

( ? )

20. 8?

5.7

.70

2.56

(?)

15-. 26

>26. 8-28.2?

9. 1-10. 6

69. 6-73. 6

78. 7-84. 2

failings ponds.

2 Residues probably held in inventory.

3 Sewage sludge: lagooned, 3.2; landfilled, 6.3; landspreading, 2,500,000 troy ounces.

♦Dry surface piles: 7,800,000 troy ounces.

Of the ultimate potential for environmental impact from silver in.

cloud seeding, Howell concluded :

Cloud seeding, if it became widespread, would result in local, temporary concen-

trations [of silver] in precipitation of the same order of magnitude as the natural

concentration in surface waters [streams, lakes, rivers, etc.]. However, the rates

of exchange [of silver in surface waters] would remain more than one order of

magnitude smaller than the principal exchange [rates] affecting the aquatic de-

partment, and they would be many orders of magnitude smaller than those affect-

ing plants and soil, even in localized areas of precipitation management. Wide-

spread and prolonged precipitation management, using silver iodide as the cloud-

seeding agent and assuming that all the silver dispersed in the course of a century

accumulated in the top two centimeters of soil, would not cause the silver con-

centration th ere to exceed the normal background [levels]. 33

33 Howell. "Environmental Impacts of Precipitation Management" : Results and inferences

from Project Sky water, p. 497 (note 17).

496

Finally, a workshop of 18 scientists which met in 1976 to assess po-

modification efforts concluded their review :

In summary, the members of the workshop felt that the points of major public

concern regarding nucleating agents (effects on plant growth, game animals and

fish, as points of special public interest) represented negligible environmental

hazards. The more subtle potential effects 'of silver-based nucleating agents, such

as a possible ability to potentiate the movement or effects of other materials of

environmental concern (other metals, pesticides, etc.) or their ability to influence

the activity of microorganisms in soils and aquatic environments,' particularly

after localized bioconcentration by plants, warrant continued research and moni-

toring activities, although any effects, if they might occur, are not expected to

involve unacceptable risks. The long term use of silver iodide, together with the

confidence which the weather modification profession has in delivery systems and

the efficacy of this material, make it unlikely that other agents will be used on

a large-scale basis in the future, unless improvements in delivery systems and

major changes in the economics of silver availability might occur.* 4

Deliberate Weather Modification

Several forms of deliberate weather modification appear worthy of

serious consideration over the next few years to a decade or so. They in-

clude precipitation enhancement (or reduction), hurricane or other

severe storm abatement or other modification, fog dispersal, hail sup-

pression, and control of lightning. The following sections attempt to

encapsulate the best, current judgment about the ecological impacts or

other etl'ects of applied weather modification technology in each of

these categories.

PRECIPITATION ENHANCEMENT

In general efforts to alter (usually enhance) precipitation patterns

can 1 >e categorized as either attempts to increase rainfall or to augment

snowpack. In the former instance the modification primarily seeks to

benefit a local economy, usually by aiding crop production: in the lat-

ter case, modification is undertaken in one area in order to benefit resi-

dent of another, usually by augmenting the snowpack in watersheds to

increase water streamflows to the advantage of downstream users. 35

/ nereased rainfall

Cooper and Jolly. Bureau of Reclamation, and Howell all provide

more complete discussions of the kinds of ecological effects which can be

expected. 1 [owell's treatment is excerpted here as follow- :

With respect to the vegetational characteristics of the environment, increasing

snmnier-convective precipitation is accompanied by a gradual transition from

desert shrnbland to short-grass prairie, to tall-grass prairie, to a sabana of mixed

grass and deciduous forest, and finally to forest * * *. Precipitation management

would tend ro shift the very diffuse boundaries of these grand divisions somewhat

westward * * *.

** Kle in. "Ecological Impacts of Nucleating Agents Used in Weather Modification Pro-'

grams" : an Interdisciplinary assessment, p. £T5 mote 154.

35 Cooper. "Ecological Implications of Weather Modification." p. 2 (note 9).

36 Cooper and Jolly. "Ecological Effects of Weather Modification : a Problem Analysis,"

p. 1 t note 1 i .

Bureau <>f Reclamation, Environmental statement for Project Skywater C note 14). How-

ell. "Environmental Impacts of Precipitation Management: Results and Inferences From

Proi«-r-t Skywater. ' p. 4sf> (note 17).

37 Howell. "Environmental Impacts of Precipitation Management : Results and Inference

Prom Project Skywater." p. 401 (note 17).

497

extreme droughts, will cause the natural vegetation of each locality gradually

to resemble that of regions now slightly moister and may moderate the secular

changes in species composition that take place in response to normal climatic

fluctuations.

The effect of precipitation management on animal populations is likely to he

mainly indirect, through its influence on habitat, rather than directly on the

! organisms. Particularly in the case of birds and small mammals, populations

depend more on the presence of suitable cover, nest sites, and food supplies than

on the weather. Though severe storms at critical times may occasionally decimate

some species, there is little expectation that precipitation management would af-

fect the frequency of such occurrences.

The best expectation presently available of the impact of summer-convective

precipitation management is that each present environmental compartment would

gradually come to resemble neighboring compartments on the moister side of the

precipitation gradient, with no apparent risk of severe disturbances' accompany-

ing this transition.

Snow pack augmentaion

As part of the Bureau of Reclamation's Colorado River Basin pilot

project (to determine the effectiveness of seeding winter orographic

9y stems for increased snowpaek and spring runoff) , a 6-year, $1 million

research project was conducted to study the ecological impacts of snow-

pack augmentation in the San Juan Mountains of Colorado. The study

aimed to assess ecological effects of a theoretical increase in snowpaek

of 16 percent a year of average snowfall and to study the range of in-

crease up to 30 percent. The report, edited by Steinlioff and Ives, in-

cludes the results of a team of 33 scientists. 38 The basic environmental

changes assessed were the addition of more snow and more silver.

Primary effects inpacting an ecosystem components were : "(1) lower

soil temperature in the spring, (2) more moisture in the spring, (3)

deeper snowpaek, and (4) more silver." 39 The following excerpts are

taken from the editors' "Summary of Key Conclusions" : 40

Initiation of shoot elongation was delayed for plants both in the tundra and

forests as a result of lower soil temperature associated with deeper snowpaek for

the species studied. These included Englemann Spruce (Picca engelmannii) ,

quaking aspen (Popirius tremuloides) , Thurber fescue (Fcstuca Thurbrrh, and

, numerous herbaceous species in both the tundra and forest meadows.

Only the lower soil temperature and greater snow depth, which might be ex-

pected to follow an increase in snowfall, have been found influential on animal

activity. A noticeable decline in forest populations of small mammals occurred fol-

lowing winters of heavy snowfall. This was most evident in the numbers of deer

mice (Peromyscus maniculatns) , but it was also found in chipmunks (Eutamias

minimus) and in Microtus spp. The basic reason for the population decline

derives from the delayed growth of essential spring foods and results primarily

from a delay in breeding so that fewer litters are produced. The delayed growth

of plants was a function of lower soil temperature and the longer snow cover.

As snow depth increased, elk (Cervus canadensis) moved to areas where snow

was shallower than 40 cm. They avoided regions with more than 70 cm of pene-

trable snow depth. A 15-percent increase in snowpaek may decrease available elk

winter range by 8 percent.

No significant increase in silver concentrations were found in the target area,

except in small areas near generator sites, after four winters of seeding. No*

deleterious effects of silver iodide additions have been noted to concentrations

which could be expected due to cloud seeding.

38 Steinhoff and Ives (eds.), "Ecological Impacts of Snowpaek Augmentation in the San

Juan Mountains, Colorado (note 11).

89 Ibid., p. 1.

40 Ibid.

498

Additional treatment of effects of snowpaek augmentation may be

the paper of Howell. 42 The latters "bottom line" conclusion, quoting

from Steinhoff and Ives ? work, is :

There should he no immediate, large-scale impacts on the terrestrial ecosystems

of these [San Juan] mountains following an addition of up to 30 percent of the

normal snowpack, but with no addition to maximum snowpacks. Further, much

of the work reported here suggests that compensating mechanisms within the

studied ecosystems are such that any impacts would be buffered, at least for short

periods of time, and of lesser magnitude than the changes in snow conditions

required to produce them.

Our work has shown three ecosystem components to be most susceptible to

increased snowfall : (1) snowbank situations at elevations above treeline ; (2) elk

herds (in other mountain ranges other big game species may be similarly

affected) : and (3) some small mammal populations, especially the deer mouse.

Xot all of these impacts are necessarily deleterious; an increase in the area of

snowbank edge habitats in alpine areas may, for example, increase the niches

available for rare plant species.

Finally, even in the small areas where we predict greatest impacts from

increased snowfall, the changes involved are unlikely to approach the magnitude

of other man-made impacts on mountain ecosystems.

However, it should be remembered that they may act in phase with other

man-made impacts and with natural climatic changes, in which case the total

effect could be much greater than our studies suggest.

SEVERE STOR^r ABATEMENT

Essentially synonymous with hurricane control, this technology

offers some promise of mitigating the onshore impacts of such major

storms by reducing their intensity and/or altering their paths, both

through judicious seeding of the storm while still well out at sea. The

"state of the art" is such that few answers of the long-term ecological

( fleets of applying such a technology are available. Cooper and Jolly 43

sketched a number of possible implications and speculated about some

of the effects. More recently. Cooper identified a number of specific

questions lie felt should be addressed before hurricane modification

research is carried out on an extensive scale : 44

1. What is the importance of hurricanes in bringing precipitation to con-

tinental areas such as eastern U.S.? Will this delivery be affected by hurricane

modification? What fraction of hurricane precipitation is actually useful and

effective, and what fraction is primarily flood-producing? Will this ratio be

affected?

2. What is the role of hurricanes in the biology of coral reefs and in the pro-

ductivity of tropical marine fisheries? There is evidence that hurricanes improve

fishing in the Caribbean ( Florida) and in the Pacific. How would control affect

the livelihood of subsistence fishermen in the Pacific?

3. How important are hurricanes as determinants of forest structure an(

growth? Influences are known from St. Vincent, New England, and tbe Solomoi

Islands, among others.

Clearly there may l>e significant ecological ramifications on severa

scales if severe storm abatement technology is applied. Yet, good re

sea rcli answers are seemingly still a ways off.

*' Welsbecker, "The Impact of Snow Enhancement," p. xil. 20f* -352 (note 101.

48 Howell, "Environmental Impacts of Precipitation Management : Results and Infer

encee From Project Skywater,*' p. 4!>4 (note 17).

1 Cooper ana Jolly, Ecological effects of weather modification: a problem analysis, Dp

85 88 i Note 1).

** Cooper. Ecological Implications of weather modification (Note 9).

499

Cold fog dispersal is now rather easily effected locally, principally

over airports, although warm fog dispersal remains more difficult and

expensive. Cooper and Jolly foresaw no significant ecological effect

, from the expected kinds of fog dispersal in the 1969 report 45 and that

conclusion was more recently restated by Cooper. 46

HAIL SUPPRESSION

An interdisciplinary assessment of hail suppression in the past, pres-

ent, and future has been recently reported. 47 The authors concluded

the technology is currently scientifically uncertain but potentially

beneficial, and one which would be widely adopted in the Great

Plains with benefits to agriculture and the American consumer. 48 As

recently as 1977, Cooper concluded that hail suppression technology

offers no likely ecological implications beyond those associated with

the effects on precipitation which would presumably attend its appli-

cations. 49

ALTERATION OR ARREST OF LIGHTNING DISCHARGES

As is the case with hail suppression technology, there does not seem

to be reason to anticipate any significant ecological effects from ap-

plying lightning alteration efforts beyond those to be associated with

precipitation affects. Again, Cooper and Jolly largely dismissed any

grounds for significant ecological concern with respect to lightning

modification in 1969 50 and Cooper in 1977 reiterated that posi-

tion. 01

Inadvertent Weather Modification

Inadvertent weather modification can be defined to include both un-

intended effects on nontarget areas of deliberate modifications aimed

at target areas, and of totally unintended modifications as a result of

man's activities not related to planned weather influences or opera-

tions. Regardless of the category, however, there are ecological rami-

fications involved.

EXTRA-AREA EFFECTS

Concern with extra area, usually downwind, effects is almost as old

as weather modification efforts themselves. The most common public

concern has been of the "rob Peter to pay Paul" variety wherein it is

alleged or at least feared that increased moisture for A's benefit

through cloud seeding must come from a B, at some point. Howell has

written the following summary conclusions about effects of cloud seed-

ing on precipitation in nearby areas ; "the assumption that augmenta-

tion of precipitation in one place must result in its diminution some-

43 Cooper and Jolly, "Ecological Effects of Weather Modification : A Problem Analysis,"

p. 83 (Note 1).

46 Cooper. "Ecological Implications of Weather Modification." p. 15 (Note 9).

47 Changnon. et al., "Hail Suppression : Impacts and Issues" (Note 12) ; Stanley Chang-

non. Barbara C. Farhar, and Earl R. Swanson, "Hail Suppression and Society." Science 200

(4840) (28 April 1978) : p. 387.

4S Changnon. Farhar, and Swanson, "Hail Suppression and Society," p. 387 (Note 47).

49 Cooper, "Ecological Implications of Weather Modification," p. 14 (Note 9).

50 Cooper and Jolly, "Ecological Effects of Weather Modification : A Problem Analysis"

(Note 1).

51 Cooper, "Ecological Implications of Weather Modification," p. 14 (Note 9).

500

in failure to appreciate (1) the role of natural atmospheric disturb-

ances in causing the convergence and ascent of moist air as the domi-

nant mechanism that makes moisture available for cloud formation

and (2) the potential of cloud seeding both for increasing the dynamic

energy of such disturbances and for increasing the efficiency with

which the storm clouds are converted to precipitation. * * * Model

studies of convective rain clouds are not far enough advanced to pre-

dict the outcomes with high confidence, but at least they offer no encour-

agement to the notion that cloud seeding robs Peter to pay Paul." 52

Howell adds: "Studies of rainfall downwind from actual summer-

convective cloud seeding operations have been inconclusive, with the

evidence tending to favor some increase out to distances of 400 kilo-

meters or so. However, the types of operations involved have been so

disparate that no general conclusions are possible. Studies of precipi-

tation downwind of winter-orographic cloud-seeding operations con-

firm the presence of increases at distances of approximately 250 kilo-

meters. The evidence, therefore, does not support the notion that

stimulation of precipitation in one area deprives another area but sug-

gests that seeding may strengthen existing precipitation systems." 53

A fuller treatment of extra area effects is provided in chapter 3 of

this CRS weather modification report.