Geoscience Reference
In-Depth Information
11
WILDLIFE AND SPECIES LOSS
Finally, climate change has dangerous impacts on wildlife and, more
generally, species and ecosystems around the world. Ecosystems have
two interesting features. To begin with, they are largely unmanaged or
unmanageable systems, and, second, they are economically far removed
from the marketplace.
The nonmarket aspect raises new questions for impacts analysis:
How can we measure the “value” of ecosystems or of endangered spe-
cies? How can we put losses in this area in a metric that can be compared
to those in market sectors such as agriculture and the costs of abate-
ment? This chapter begins with a review of the potential impact of cli-
mate change on species extinctions and ecosystems and then turns to
the thorny issues of valuing those impacts.
THE SIXTH MASS EXTINCTION?
According to biologists, there have been fi ve mass extinctions on
earth in the last half-billion years. Conservation biologists warn us that
the combination of climate change and other human infl uences will
cause a sixth mass extinction over the next century.
1
The history of life has witnessed several distinct surges and extinc-
tions of life on earth. Figure 20 shows an estimate of the extinction rate
for marine organisms, for which records are more complete than is ter-
the spikes, and scientists attribute them to events such as asteroid colli-
sions, volcanic eruptions, glaciations, and sea-level rise. The Permian-
