144 The impactsof climate change
will aid the growth of some types of plants leading to increased crop
yields.Sensitivity, adaptive capacity and vulnerability: some
definitions^2
Sensitivityis the degree to which a system is affected, either adversely
or beneficially, by climate-related stimuli. These encompass all the ele-
ments of climate change, including mean climate characteristics, climate
variability, and the frequency and magnitude of extremes. This may be
direct (e.g. a change in crop yield in response to a change in the mean,
range or variability of temperature) or indirect (e.g. damage caused by
an increase in the frequency of coastal flooding due to sea level rise).
Adaptive capacityis the ability of a system to adjust to climate
change (includingclimate variability and extremes), to moderate po-
tential damage, to take advantage of opportunities or to cope with the
consequences.
Vulnerabilityis the degree to which a system is susceptible to, or
unable to cope with, adverse effects of climate change, including climate
variability and extremes. Vulnerability is a function of the character,
magnitude and rate of climate change and also the extent to which a
system is exposed, its sensitivity and its adaptive capacity.
Both the magnitude and the rate of climate change are important in
determining the sensitivity, adaptability and vulnerability of a system.However, because, over centuries, human communities have adapted
their lives and activities to the present climate, most changes in climate
will tend to produce an adverse impact. If the changes occur rapidly, quick
and possibly costly adaptation to a new climate will be required by the
affected community. An alternative might be for the affected community
to migrate to a region where less adaptation would be needed – a solution
which has become increasingly difficult or, in some cases, impossible in
the modern crowded world.
As we consider the questions posed at the start of this chapter, it will
become clear that the answers are far from simple. It is relatively easy
to consider the effects of a particular change (in say, sea level or water
resources) supposing nothing else changes. But other factors will change.
Some adaptation, for both ecosystems and human communities, may be
relatively easy to achieve; in other cases, adaptation may be difficult, very
costly or even impossible. In assessing the effects of global warming
and how serious they are, allowance must be made for response and
adaptation. The likely costs of adaptation also need to be put alongside
the costs of the losses or impacts connected with global warming.