Geoscience Reference
In-Depth Information
when conditions and processes clearly differed from
those of today. We can think of these features as
relics
of the past, but it is important to recognize that they
are not just fossils; they influence the present-day processes
to a considerable degree. Second, the valley is a complex
system or
ecosystem
, with many dynamic linkages
between the different elements. Changes in any one factor
or process work through to affect other parts. These
changes can be amplified through positive feedback or
damped down by negative feedback. Predicting what type
of feedback will occur, and the consequent changes in the
whole system, is no easy matter. For example, a major
present-day concern is the attempt to predict the effects
of global climatic change on environmental systems, at all
scales and in all parts of the globe. Will the new climatic
impulses lead to changes which will then stabilize by
homeostasis, or will new and as yet unpredictable systems
be born?
Global climatic change is just one major part of
physical geography where human activities are involved
in two-way interactions with physical environments.
Human activities clearly have the power to cause major
alterations of the physical environment, and equally are
themselves affected by the limitations and opportunities
which the physical environment presents. These inter-
actions make up what is termed the field of
environmental
management
. All too easily people trigger changes in
environmental systems more far-reaching and destructive
than was intended. Mostly this is not due to malice,
but because people simply do not understand all the
ramifications of their actions. We shall study many
examples in the rest of the topic. In almost every case
the lesson will be the same. If ever we are to manage the
physical environment without damaging it, we need to
understand the physical, chemical and biological processes
working in different physical environments, how environ-
mental systems function as a whole, how they change and
how they respond to external conditions. In this sense the
overall aim of this topic is to improve our understanding
of such difficult matters, and in so doing bring benefits
to human society. As Trudgill (2001) has emphasized,
foolproof predictions of environmental futures may be an
unattainable goal, but by a better understanding of the
science underlying environmental processes and systems
we shall be better prepared to manage the physical
environment sympathetically and to respond to foreseen
and unforeseen environmental change.
KEY POINTS
1
Environmental processes are the means by which the physical landscape is being shaped. The processes
involve physical, chemical and biological reactions taking place above, at and underneath the surface of
Earth. Present-day processes are governed by present-day factors, and also by factors which have been
inherited from the history of the landscape being studied.
2
Such is the complexity of physical environments that a systems approach helps us to understand
them. The use of morphological systems, cascade systems and process-response systems is well
established in physical geography, and leads to studies of equilibrium, positive feedback and negative
feedback which have proved so useful in helping us to understand how human beings interact with their
environment.
3
Physical geography has advanced its knowledge, understanding and status by adopting rigorous scientific
approaches, in the field, the physical and chemical laboratory, and the computer laboratory. Paradigm shifts
in the history of the discipline have come through the visions of key workers in the subdisciplines of
geomorphology and Earth history, climatology, biogeography and conservation.
4
Not all environmental systems behave in an equilibrium manner. Chaotic and non-equilibrium conditions
exist which are completely unpredictable. However, by understanding how environmental processes and
environmental systems operate, we shall be better placed to manage our unpredictable future.
5
Physical geography is an applied science. In countless ways, each branch of the subject has contributed
to the betterment of human societies.
