The sustainability transition - Environmental and Human Security in the Arctic - page 84

find it natural to treat anthropogenic forces as exogenous and generally minor
perturbations and to construct models focusing on specific components of
ecosystems through a liberal use of ceteris paribus assumptions. A number of
observers have argued that this analytic strategy had serious drawbacks from
the start. Whatever our view of this history, however, it is clear now that such
a strategy cannot provide the knowledge needed to make progress towards the
sustainability transition and that we require new tools to achieve sustainable
ecosystems.
Ecosystems
Whereas members of earlier generations of scientists were satisfied to focus on
subsystems and typically to concentrate on efforts to understand the popula-
tion dynamics of individual species, recent decades have witnessed a sharp
turn towards holistic studies that rest on the premise that the interdependen-
cies among the elements or components of ecosystems are too great to ignore
or to abstract away through the introduction of assumptions. Certainly, there
are those who cling to the development of reductionist models in the interests
of preserving the logical power of these constructs; they take the view that the
analytic price of moving towards integrated models will exceed any benefits
likely to accrue from a more holistic mode of thought. Even so, it is clear that
the introduction of whole ecosystem perspectives is a major development that
is not likely to go away during the foreseeable future (Golley 1993).
Current thinking about ecosystems also features a heightened aware-
ness of dynamics, including non-linear and chaotic processes, rapid change
events, cascades and regime shifts (Ludwig et al . 1993). Even in the absence of
human interventions, ecosystems are prone to more or less dramatic changes,
and there is no basis for assuming that these systems will tend to return to
some prior equilibrium in the wake of significant disturbances. Far-reaching
changes, often described as regime shifts, are by no means uncommon; less
dramatic but still significant changes occur as a matter of course. Under the
circumstances, arguments based on the premise that biophysical systems
exhibit strong equilibrating tendencies are doomed to failure.
What is the significance of these trends for the development of tools
needed to support the sustainability transition? Many familiar models that
are widely used in efforts to manage ecosystems of interest to humans are
of limited value; their application may actually prove counterproductive in
some domains. A prominent example involves the widespread reliance on
maximum sustainable yield (MSY) models in fisheries management (Larkin
1977). Because MSY models focus on single (or at most a few) species and do
not address the dynamics of the larger ecosystems to which targeted species
belong, these models can and often do produce results that are misleading as a
basis for establishing allowable harvest levels. Beyond this lies the challenge of
modelling complex systems without an undue loss of analytic rigour. Partly,