WMOD00470

• Project Name: Project Skywater
• Title: Environmental Impacts of Precipitation Management: Results and Inferences from Project Skywater
• Date: 6/6/1977
• Weather Modification - Doc Type: Report

500

highest potential for effect from weather modification
has indicated no clearly adverse effects, emphasis on
hurry-up studies to ward off imagined catastrophes, such
as species extinctions, no longer appears justified. Sec-
ond, assessment of long-term effects of weather modifica-
tion on the environment as a whole is assuming rela-
tively greater importance, and means for such
assessment are under review.
For this assessment, the process approach encounters
severe difficulties. How the fragmentary and mostly
tentative results of impacts on specific environmental
components should be formed into an overview of ef-
fects on the environment as a whole depends on assump-
tions about the strength and direction of intercomponent
effects. Not enough is know about these effects for more
than a speculative exploration. As Cooper (1973, p. 102)
noted,

. . . ecosystems do not necessarily respond in ways that
would be predicted from a knowledge of the properties
of their individual components. . . . The complexity and
variability, in both space and time, of real ecosystems is
such that it is probably impossible to devise a generally
agreed upon quantitative description against which fu-
ture states of the system can be judged.

d. Holistic approach

An alternative approach is the holistic, integrative ex-
amination of the general properties of environments as
a whole after they have developed under the influence
of weather differences similar to those expected to re-
sult from weather modification. The Special Commission
on Weather Modification of the National Science Foun-
dation (1966, p. 20) pointed out that among the avenues
open to improved forecasting of biological effects is
"examination of areas biologically and climatically
analogous to the changed and unchanged situations." .
Howell (1976) has shown that short-term and middle-
term effects (up to 10 years or so) may be analyzed by
observation of environmental system responses to na-
tural trends in the weather elements subject to modifi-
cation, since natural variations over time spans of 2-10
years exceeding those attainable by weather modifi-
cation are frequent. A few such studies have been made,
especially respecting the recovery of vegetation from the
strain of severe drought, but the opportunity appears
great for more systematic and widespread application
of the method.

e. Comparison ot environmental communities
For longer-term effects, especially those spanning the
natural successional changes leading to a climax vege-
tational community, the preferred approach is by com-
parison of environmental communities that differ
in the properties expected to be affected by weather
modification but that are otherwise as similar as pos-
sible. A well-known example is the vegetational gradient
of the Great Plains. Another example, currently under
study in the Uinta National Forest, is comparison
of vegetation in the interior of a forest stand with
that a few tens of meters inside the stand border, where
snow blown from a nearby meadow accumulates in late-
lying drifts while soil, aspect, temperature, and other

Vol. 58, No.6, June 1977

conditions are substantially identical. The same general
approach characterizes the phytosociological studies of
the San Juan Ecology Project (Dix et al., 1973), which
established gradients across many stands under different
conditions of climate, elevation, and aspect, wherein the
principal component of the variations was found to be
strongly related to snow duration. This, in turn, was
found strongly related to slope aspect. By studying
nearly adjacent plant communities under natural condi-
tions that simulate the changes expected from precipita-
tion management, potential impacts may be assessed.

f. Study ot natuml and acculturated components
Consideration of the wide variety of landscapes that may
be subjected to precipitation management suggests that
they exemplify "wild" and "cultivated" components that
are combined in dramatically varying proportions and
modes. In every wilderness area, there is some degree
of acculturation, game management being an example.
Even in the city, there are some wild pockets. Changes
within the wild compartments are for the most part
genetically controlled. They include the entire repertory
of responsive strategies that have accounted for the
evolution and persistence of species and, by and large,
render the prevailing ecosystems extremely robust, resil-
ient, and durable under a wide range of stresses and
insults, natural and man made.
The acculturated components, on the other hand, are
governed by human actions. These actions are only
partly rational and predictable, and many of them are
responsive to stimuli quite dissociated from the environ-
mental situation. Whether a field is plowed, left fallow,
or planted with one crop or another may be governed
by land-bank politics, foreign markets, or the latest de-
velopments in crossbreeding. In this situation, the major
manipulations of the ecosystem, responsive to a rela-
tively small number of decision-making inputs, cause
changes so drastic that they overwhelm the smaller and
more indirect consequences not only of other decisions
(e.g., which fertilizer or insecticide to use) but also of
all but the strongest environmental variables.
In landscapes having a high level of domesticity, it
becomes more and more certain that the environmental
consequences of precipitation management (which in
wild landscapes follow natural laws at least potentially
knowable) will be less and less subject to natural law
and more and more subject to unpredictable human be-
havior quite unrelated to weather modification.

g. Summary
As the result of painstaking research, weather modifica-
tion impacts are no longer seen as the horrendous threat
they were depicted to be a decade ago (Sargent, 1967),
and familiarity has not bred contempt. Rather, it might
be said that the environmental problems posed by
weather modification are being brought into perspective
and that that perspective is giving them the appearance
of a familiar landscape, in both the physical and institu-
tional senses. The task now is not that of arming against
a suspected enemy but of understanding a potential
friend.