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Evaluating Ecological Impacts:
A Conceptual Framework
MILTON RUSSELL
University of Tennessee
and
Oak Ridge National Laboratory
Editors' Note: This chapter differs from most of the others in this boom It is,
in essence, a personal essay prepared at our request by He author: It presents
a particular perspective on the evaluation of ecological impacts. We found it
very stimulating and hope our readers will fad it equal) so.
A central thesis of ecology is that everything is connected to everything
else; thus, any perturbation of an ecological system willican have effects
that alter conditions for life of all other components of the system, and also
redound upon the perturbing event itself. Some of these linkages may be
strong; others weaL Some may attenuate quickly over space and time, as
do ripples in a pool; others may amplify and spread, as does the triggering
event for an avalanche.
Human actions are among those perturbing events, and one of the
reasons for the great interest in ecology is that it can provide useful
insights into the fuller implications of human actions. Then, armed with
greater understanding of these effects, decision makers can adjust behavior
accordingly. They can seek to ameliorate or mitigate harmful effects or
augment desirable ones. Note, however, that any influence on decisions
of further insights on prospective outcomes depends not only on their size
and nature. Outcomes will be serious or trivial, beneficial or harmful, or
may just "be," depending on the values brought to the judgment, and on
who is doing the judging.
The purpose of this essay is to explore a basis on which these judgments
might be made. The range of potential views is large—in Chapter 4, Marek
and Kassenberg provide a formulation vely different from that presented
below. The literature is also enormous, composed as it is of much of
what has been written on the place of man in nature. This essay surveys
31
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ECOLOGICAL RISKS
neither that range of views nor that literature, but instead seeks to provide
a sketch of an approach to valuing ecological change from a perspective
that places humans at the center. Many may disagree with this formulation
or find it too narrow or, at best, incomplete. However, this view deserves
consideration if only because the humans who by action or inaction may
alter the course of future events are the persons living now, and because
the presumption that they seek to improve their welfare (defined broadly)
rather than harm it seems reasonable.
In the human-centered view explored in this essay, the ecological
system and its natural components are treated as factors of production and
elements in consumption, and are not presumed to possess value in and
of themselves. Of course, humans may value natural systems for their own
sake witness the affection for wilderness in the United Sates- and that fits
well into the human-centered view. This essay knowingly avoids the more
profound discussion of mankind as endogenous to natural systems and
adopts an admittedly artificial division. Changes in the ecological system
are judged by whether or not they add to or detract from the quality of life
for the human population affected. Saying this, however, does not make
decision processes much more straightforward. Key questions in valuing
remain, some of which are identified below.
A TYPOLOGY OF CONSEQUENCES OF CHANGE
The discussion that follows starts by postulating an existing ecological
situation, and then examines the major consequences to consider in deciding
whether or not to change it. Such change could be of different sorts. For
example, it could be to relieve existing stress on an ecological system by
decreasing the amount of pollution that is affecting negatively some of its
components. It could be to change relative species abundance through, for
example, cultivating grasslands or logging forests. It could be to change the
extent of human impact by enhancing access to a secluded area with a new
road or, alternatively, by restricting it. It could be to dam a free-flowing
river, or to drain and fill a swamp, or to convert wetlands to dry. Whatever
the change, it will affect the ecological system and, in turn, those effects
will impact humans in various ways.
The first way in which humans will be affected is through changes in
the magnitude of economic contribution from the ecological system. That
economic contribution can take many forms. One form is the yield of
materials desired by humans; these materials are counted as part of the
Gross National Product (GNP). Forests provide timber and habitat for
animals and plants of direct use to humans. Rivers, lakes, and oceans
provide fish and birds that are important to diets. Grasslands provide
grazing and hay for domestic animals and habitat for useful wild ones.
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ENVIRONMENTAL MANAGEMENT CONCEPTS
33
Cultivated acreage is also part of the ecological system. Shifts in its
condition that affect output for example, due to pollution or to a change
in population of beneficial insects flow immediately to the GNP.
Indirect economic effects are also the consequence of changes affecting
the ecological system. Change in cultivation patterns or amount or type of
forest cover affect water flows with possible consequences of flooding, for
example. These changed hydrologic patterns may require expenditures to
onset an undesired effect, or they may have direct economic consequences
through destruction of property. Wetlands have been shown to be efficient
sinks for pollutants of various kinds, and their diminution may lead to de-
clines in productivity of water bodies or to the need for capital expenditures
to treat effluents or to prevent non-point pollution. Such indirect economic
effects may or may not flow through the GNP, but in principle they are
quantifiable and definable as factors in the overall output of the economy.
Other factors are not as easily evaluated in the same way. These are
the indirect amenity values of the environment which add or detract from
human satisfaction. An obvious example is the value of the recreational
opportunities presented by forests, streams, and oceans. Still less direct,
but no less real, are the benefits received by people in viewing a pleasing
natural vista, in seeing or listening to wild birds, or in viewing animals in
the wild.
Another effect felt by humans which must be considered here is the
"existence value" which components of natural systems may have to those
who never experience them directly. For example, many people would feel
a deep sense of loss to hear that the giant panda of China or the elephant
of Africa had been rendered extinct in the wild, even if they had never
seen these animals there, nor expected to. Similarly, the non-fisherman
may mourn the loss of a species from a river, or rejoice when salmon
return to streams where they had been absent for a long time. This sense
of responsibility and stewardship goes deep. It is not bounded by direct
benefits or measured by an accountant's economic rationality. These values
are difficult to measure as compared to, say, changes in the output of a
fishery, but they have substantial importance where humans can express
their interests in ecological outcomes.
Ecological change caused by human activities characteristically leads
to less diversity in systems, and hence to greater vulnerability in the pres-
ence of shocks. Thus, monoculture increases the possibility of disastrous
results from aberrant weather. Water control systems designed for 100-year
floods can be overcome by 1,000-year episodes, with catastrophic results.
Narrowed gene pools can leave important plant or animal populations
susceptible to new disease. These risks are components of the human
interest in ecological change which present misgivings, even when they are
sufficiently vague as to defy explicit consideration.
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ECOLOGICAL RISKS
Another risk factor is uncertainty, which comes in Ho forms. The first
is lack of knowledge of what the second and higher order effects of a change
will be, and how they will affect the human condition. The ecological havoc
wrought by introduced plant and animal species are well known: rabbits
in Australia; deer in New Zealand; the African bee in Latin America; the
gypsy moth, English sparrow, and kudzu in the United States, to name a
few. The harmful downstream effects of the Aswan Dam have been widely
reported; some desertification in Africa and elsewhere has been traced to
initially beneficial changes in agriculture practices. We have a tendency to
remember the bad surprises and to ignore those which turned out well; for
example, one can scarcely imagine agriculture without the massive exchange
of plants and animals which has taken place. However, the point is that by
definition there will be unforeseen effects, since those which are understood
can be factored into a decision. Therefore, there will be an unquantifiable
residuum of impacts for good or ill from any perturbation of an ecological
system, and that fact alone offers reason for caution.
The second form of uncertainty is in how affected factors will be valued
in the future and under changed conditions. The point is obvious when it
comes to plant and animal species rendered extinct; their potential uses will
never be realized. This form of uncertainty also works the other way. Some
dams built to produce electric power and to foster navigation in the United
States now have lake recreation as their most important contribution to
human welfare. Such unexpected results are not due to the failure to
comprehend how the ecological system would respond to perturbation, but
also due to changes in how much humans care about what happens.
ISSUES IN EVALUATING CHANGES
Consequences of ecosystem changes must be considered by decision
makers when making social choices. How might the effect on "the quality
of life for the affected human population" be determined, since it is often
the presumed basis for the decision?
Three issues come immediately to mind. The first is in the dimension
of space what is the scope of the human community whose well being is to
be considered? The second is in the dimension of time what consideration
is to be given to those who will live in the future? The third is in whose
wishes count how will different wishes be considered in reaching a social
judgment?
Take first the dimension of space. Ecological, economic, and social
effects of a change may all attenuate rather quickly from the point of
impact. When they do, the community affected is readily circumscribed
and ejects upon it relatively easy to discover and describe. For example, a
single, small river may be affected by acid mine drainage. Decisions may
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ENVIRONMENTAL MANAGEMENT CONCEPTS
35
still be controversial because their distributional effects are important, but
the problem is at least not unmanageable due to failure of political and
. .
economic institutions to encompass all players.
In other cases, all of the meaningful effects of a change may reside
within the boundaries of a nation-state. The scope may be large and
the facts less clear, but in principle the institutions would be in place to
consider the interests of competing parties. In yet other circumstances,
however, significant effects cross national boundaries. The harmful effects
of acid rain are one example; the beneficial effects of actions to preserve
tropical forests or to protect symbolically important animals such as the
wild elephant are others.
When ecological boundaries cross political ones, the potential lack
of coincidence between the community with the ability to decide and the
community that bears a share of the impact is clear. The human-centered,
maximizing view would suggest that only those who share in both the ori-
gin and the impact of the change would have their wishes fully reflected,
although those wishes could include a measure of altruism. However, this
does not doom those outside to having no possible voice in the final out-
come. If the issue is important enough, they can either attempt to achieve
an agreement more to their liking through recourse to a superordinate
power, as with an international treaty (e.g., the Montreal Protocol on
Ozone Depletiony, or seek to negotiate side payments or to offer threats
that cause interests to coincide with effects (e.g., the proposed debt-for-
forest swaps between parties in developed and in developing countries).
In either case, interests are brought together albeit imperfectly because of
the expense and difficulty of making bargains across institutional divisions.
In doing so, evaluations of ecological effects by all those affected in the
present are elicited, and in some way are the basis for action.
EVALUATING FUTURE CONSEQUENCES
The ecological effects of a human perturbation run forward in time
as well as outward in space. They may attenuate readily: the fishery in
the James River of Virginia recovered in a few years when paper and
pulp pollution was controlled; and in just 50 years gross evidence of
human habitation has disappeared in the Great Smoky Mountains National
Park. On the other hand, effects may be as permanent as the extinction
of a species or as near-irreversible as the desertification of portions of
northwestern China, which occurred some 1,000 years ago. The evaluation
of ecological change requires a decision as to whether persons in the near
or distant future are to have their interests considered; if so, what those
interests are; and finally, how those interests are going to be accommodated.
Whether (and how) to account for the wishes of future generations
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ECOLOGICAL RISKS
of humans is one of the most difficult conceptual problems in making
decisions regarding environmental protection. At the limits the answer
is easy: human society does value contributions to the welfare of future
generations; but it does not care enough to embrace risk of its own suicide
to contribute to that welfare. Away from these limits, however, no simple
or absolute answers hold. And it is away from these limits that most
important environmental questions exist.
With regard to the second question of identifying the interests of
future generations, the human-centered view suggests that they will be
something like those of present generations, i.e., there will be concern
both for narrow economic output and for the broader values of natural
systems as described above. Consequently, one objective should be to
endow subsequent generations with a combination of the undifferentiated
ability to satisfy economic wants with actions taken to limit the diminution
of the diversity of ecological systems.
In achieving this, one approach is to assess future outcomes through
the use of some positive discount rate. There are several possible value
bases for applying this approach, but space permits discussion of only one.
That basis would purport to leave an endowment no less rich than the one
currently enjoyed. In that sense, future generations would be treated as if
their wants had equal standing with present generations.
One predicate of this approach is that resources not consumed in
the present will accumulate at a positive rate to be the basis for future
consumption, including environmental protection. From this it follows that
it is neither necessary nor wise to invest as much today in preventing
future harm as the projected cost of that harm to future generations. It is
not necessary in meeting the equal endowment goal because, assuming the
correct discount rate is chosen, future generations will be at least as rich
as those living today due to the return from investment taking place in the
present. They will be able to afford to take care of their problems as well
as we can. It is similarly not wise.
If investment in preventing future harm is not placed on the same
discounted basis, as is investment in producing other goods and services,
resources will be allocated inefficiently and total output will suffer. Future
generations as they judge it will be worse off than they need to be. This
is because by depleting resources to overcorrect problems now, we deny
future generations the resources that could do the job at less sacrifice to
them. This proposition has much to be said for it. In its most general
form, it undergirds consumption and investment decisions of all modern
economies. When it comes to ecological protection, however, caution
should be exercised in its application.
One critical assumption inherent in this approach is that resources are
fungible, so that future wants can be satisfied by whatever set of resources
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ENY7RONME~^ ~AGEME~ CONCEPTS
37
exist then, as long as enough of them are available. This assumption is
brought into question when it comes to ecological protection because of
the irreversible nature of some changes. Extinct species cannot be brought
back, however rich in other assets a future society may be. Their loss may
be seen as an irremediable decrease in future welfare. On the other hand,
it might be deemed presumptuous for us, today, to determine the pattern of
consumption of those who live in the future. While they would thank us for
leaving them "better off" in the abstract, their values may be such that they
would not prefer what we prefer, given our life experiences. Some humility
may be in order, for example, before we decide to save some species at high
cost in future production ostensibly for the benefit of [mire generations.
The fact that those in the future are our wards (in that they have a vital
interest in decisions they can't affect) means that we bear an obligation to
them. But it is not obvious that fulfilling that obligation requires handing
on a specific endowment.
Another assumption is that capital will continue to accumulate, or else
that any future cataclysmic change would affect all capital equally. Human
history has already provided evidence of wars and other events which have
driven civilization backwards to greater reliance on natural systems, to
a point from which progress could start anew. It could happen again.
Perturbation of these systems to the detriment of their natural productivity
may be of little consequence when man-made capital and technology are
present to replace their output, but may be of an entirely different order
of effect if the continuity of society is disrupted. For example, aquaculture
may make natural fisheries unnecessary, but regrowth of a future civilization
may be seriously handicapped if natural fisheries have been destroyed by
pollution. Or, domestic hybrid animals and plants that are highly productive
with intensive care may be unable to survive altered circumstances, and if
native species are not available, there will be nothing on which people then
living can depend.
These elements are joined by the fact that the time scale for ecolog-
ical change is so long that decisions taken today affect not just the next
generation but potentially affect generations far into the future. With any
positive discount rate, the implication is that any actions today are of little
importance to the well-being of distant generations. While there may be
something to be said for this view in some circumstances, when stated
baldly it gives many people pause, especially when it comes to ecological
change.
A reasonable conclusion to be drawn from all this is that discounting
is useful when assessing future effects, but only as a starting point. It must
be used with caution and with full understanding of its assumptions and
implications when long-term ecological change is at issue.
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ECOLOGICAL RISKS
ECOLOGICAL VALUES AND OTHER VALUES
This essay thus far has treated ecological changes and their effects on
human welfare in isolation from the motivation that brings them about.
That motivation includes increased economic production and resulting
social change.
In some cases, ecological perturbation is the direct and intended effect
of actions to increase production. Dams are built to produce electric power
and to prevent floods, and in the process drown valleys and change the flow
of rivers. Swamps are drained and forests cleared to increase croplands.
Noxious insects and animals are controlled to prevent disease and to lessen
damage to economically valuable foodstuffs and materials. New species are
introduced to yield higher returns.
In other cases, ecological perturbation is the unintended consequence
of actions pursued to increase production. Acid water is pumped from coal
mines to free deeper seams for exploitation, but it changes the character
of streams. Effluents from factories producing goods desired by people
introduce chemicals into water bodies which can destroy living organisms
or change their relative abundance. Waste heat from power plants changes
the biota in the receiving water body, as does the effluent from domestic
sewage treatment plants. Air emissions from coal combustion changes
the pH of rain. Indeed, virtually all production and consumption has an
unintended effect on surrounding ecosystems, sometimes positive but often
negative.
To avoid such effects, the activity must be eliminated or modified, and
this has the first-order effect of decreasing the output of the economic goods
sought. If the good is not produced or consumed, the resources devoted to
it are available for transfer to an alternative use, but will produce output
which by definition has lesser value or it would have been chosen in the
first place. Alternately, the resources consumed in building and operating
pollution control devices are not available to produce other desired goods
and services.
In short, avoiding or fostering ecological change has costs. The ques-
tion in a human-centered value system is whether those costs are worth
bearing. The easy answer is that it depends it depends on whether the
total welfare is enhanced or reduced. This formulation gives the conse-
quences of ecological change exactly the same standing as the benefits
received from direct economic production. ~ade-offs among alternative
ways of meeting human wants can be made and indeed must be made.
Several cases may be distinguished when avoiding or fostering eco-
logical change is contemplated. In some cases, the overall magnitude of
economic output, even narrowly conceived, is increased. For example, the
cost of reducing an effluent may be less than the added return from an
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ENVIRONMENTAL MANAGEMENT CONCEPTS
39
enhanced fishery. Different persons gain and lose, but the total economic
product is increased. In other cases, the losses in output are more than
made up by ecological contributions to health or welfare of the sorts de-
saibed above as indirect economic impacts. In still other cases, the loss of
direct output is more than offset when existence value, uncertainty, or fu-
ture effects are considered. There is, of course, also the class of cases where
the cost of reducing an environmental insult is greater than the benefits
derived, even when the broadest definition of benefits is used. In this class
of cases, no control action is justified when tested against human-centered
criteria.
Such a formulation of the structure of decisions gives rise to two
problems. The first is identification of the boundaries within which the
well-being of inhabitants are to be considered, a matter already discussed.
Does this group only consist of persons within some political boundary and
their heirs, or are the wishes of affected others to be considered? On the
output side, the issue is similar.
The second problem has to do with the distribution of gains and losses.
Only rarely will these distributions be coincident; therefore, either action or
inaction will leave some better off and others worse off, notwithstanding the
question of whether the change in overall outcome is positive or negative.
The fact that compensation of the losers by the winners may be possible
does not, in the view of some, alter the case as long as all individuals
themselves do not judge the outcome as satisfactory.
How are these diverse views to be taken into account? And who
decides? This intriguing and daunting question illuminates the complexity
a social system faces in determining how to evaluate ecological impacts,
and then in choosing what to do.
This discussion has proceeded along only two dimensions—ecological
impacts and the sum of direct and indirect economic benefits, including
such matters as existence values. However, the total decision matrix is
far richer and other elements, including but not limited to distributional
concerns, must be factored into any decision.
FROM CONCEPT TO PRACTICE
This essay has sought to describe a conceptual framework for how
the products of ecological science might be used in making decisions that
affect natural systems. The value system used on this essay puts human
preferences at the center.
This essay does not consider the difficulty of obtaining data necessary
to make wise decisions. These data are almost always expensive to acquire,
will remain incomplete, and will be subject to change. Hence, any decision
will have an unknown and unknowable outcome. This fact suggests that a
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ECOLOGICAL RISKS
premium should be placed on a decision that is robust in the presence of
error, so that the possibility of irreversible damage is lessened.
The framework presented has also leaped over the problem of iden-
tifying human preferences, i.e., that set of outcomes which would indeed
make people better off. The viewpoint is that of naive utilitarianism, with
a benevolent entity seeking to maximize the sum of human welfare within
a political boundary. That entity takes account of such matters as the
distribution of benefits and costs. It takes an altruistic attitude towards
those separated by space and time, but from the viewpoint of an outsider,
not a participant.
Actually, the difficulty in doing this through any sort of political process
is great enough when a circumscribed population is considered. It becomes
greater still when small effects on large numbers of far-distant persons
are considered. Thus, when concern for the values of future generations
are taken into account, the matter becomes, strictly speaking, unknowable.
Even when objective outcomes are assumed to be known, how they are
valued by people, much less how to aggregate those values, remains a
serious problem.
The point is that the results of ecological understanding can inform
decisions, but such understanding alone cannot dictate them. Ultimately,
those decisions rest on the values of the persons making them. Ecology's
job is to make sure that the full consequences of alternative decisions are
illuminated. Some of the ways in which such knowledge could be used, and
in fact is essential, have been outlined here. It is the premise of this essay
that the task of malting ecological insights available to decision makers is
of service whatever the value system used for final decisions.
RELATED READINGS
Brundtland, G.H. 1987. Our common future. Report of the World Commission on Environ-
ment and Development. Oxford: Oxford University Press.
Dubos, Rene. 1980. The wooing of earth. New York: Charles Scribner's Sons.
Hardin, G., and J. Baden, eds. 1977. Managing the commons. San Francisco: W.H. Freeman
and Co.
MacLean, D., ed. 1986. Values at risk. Totowa, New Jersey: Rowman and Allenheld.
Partridge, E., ed. 1981. Responsibilities to future generations: Environmental ethics. Buffalo,
New York: Prometheus Books.
Sagoff, M. 1988. Ike economy of the earth: Philosophy, law, and the environment.
Cambridge: Cambridge University Press.
Stokey, E., and R.Z Larsen. 1978. A primer for policy analysis. New York: W.W. Norton.
Representative terms from entire chapter:
future generations
