Environmental Engineering Reference
In-Depth Information
is said to be in a steady state. Because of the
complexity of the earth/atmosphere system, the
great number of pathways available to the energy
and the variety of short and long-term storage
facilities that exist, it may never actually reach
that condition. Major excursions away from a
steady state in the past may be represented by
such events as the Ice Ages, but in most cases the
responses to change are less obvious. Changes in
one element in the system, tending to produce
instability, are countered by changes in other
elements which attempt to restore balance. This
tendency for the components of the environment
to achieve some degree of balance has long been
recognized by geographers, and referred to as
environmental equilibrium. The balance is never
complete, however. Rather, it is a dynamic
equilibrium which involves a continuing series
of mutual adjustments among the elements that
make up the environment. The rate, nature and
extent of the adjustments required will vary with
the amount of disequilibrium introduced into the
system, but in every environment there will be
periods when relative stability can be maintained
with only minor adjustments. This inherent
stability of the environment tends to dampen the
impact of changes even as they happen, and any
detrimental effects that they produce may go
unnoticed. At other times, the equilibrium is so
disturbed that stability is lost, and major
responses are required to restore the balance.
Many environmentalists view the present
environmental deterioration as the result of
human interference in the system at a level which
has pushed the stabilizing mechanisms to their
limits, and perhaps beyond.
Running contrary to this is the much less
pessimistic point of view expressed by James
Lovelock and his various collaborators in the
Gaia hypothesis (Lovelock 1972; Lovelock and
Margulis 1973). First developed in 1972, and
named after an ancient Greek earth-goddess, the
hypothesis views the earth as a single organism
in which the individual elements exist together
in a symbiotic relationship. Internal control
mechanisms maintain an appropriate level of
stability. Thus, it has much in common with the
concept of environmental equilibrium. It goes
further, however, in presenting the biocentric view
that the living components of the environment
are capable of working actively together to
provide and retain optimum conditions for their
own survival. Animals, for example, take up
oxygen during respiration and return carbon
dioxide to the atmosphere. The process is
reversed in plants, carbon dioxide being absorbed
and oxygen released. Thus, the waste product
from each group becomes a resource for the other.
Working together over hundreds of thousands
of years, these living organisms have combined
to maintain oxygen and carbon dioxide at levels
capable of supporting their particular forms of
life. This is one of the more controversial aspects
of Gaia, flying in the face of majority scientific
opinion—which, since at least the time of
Darwin, has seen life responding to
environmental conditions rather than initiating
them—and inviting some interesting and possibly
dangerous corollaries. It would seem to follow,
for example, that existing environmental
problems which threaten life—ozone depletion,
for example—are transitory, and will eventually
be brought under control again by the
environment itself. To accept that would be to
accept the efficacy of regulatory systems which
are as yet unproven, particularly in their ability
to deal with large scale human interference. Such
acceptance would be irresponsible, and has been
referred to by Schneider (1986) as 'environmental
brinksmanship'.
Lovelock himself has allowed that Gaia's
regulatory mechanisms may well have been
weakened by human activity (Lovelock and
Epton 1975; Lovelock 1986). Systems cope with
change most effectively when they have a number
of options by which they can take appropriate
action, and this was considered one of the main
strengths of Gaia. It is possible, however, that
the earth's growing population has created so
much stress in the environment, that the options
are much reduced, and the regulatory
mechanisms may no longer be able to nullify the
threats to balance in the system. This reduction
in the variety of responses available to Gaia may
