Geoscience Reference
In-Depth Information
This does not mean we should simply throw up our hands and walk
away from the problem. At the least, we need a better way to sort out
ecosystems and species in urgent need of preservation from those of
lower priority. Some biologists suggest that simply estimating the num-
ber of species at risk is an inappropriate measure of biological impor-
tance.
Other metrics would emphasize such characteristics as functional
or behavioral diversity and the ability to rebound after an environmen-
tal shock. These aspects were analyzed by biologists Sean Nee and
Robert May. They studied how much of the genetic diversity or infor-
mation coded in DNA—the tree of life, in Charles Darwin's phrase—
was lost in past extinctions. The idea is that all species are not equally
important. For example, the extinction of the dodo bird, with no gene-
tically close relatives, would lead to a greater loss in diversity than the
loss of one of the 3,000 mosquito species. Their surprising fi nding was
that approximately 80 percent of the underlying tree of life survived
even when 95 percent of species were lost.
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Other scholars such as Harvard economist Martin Weitzman have
an important task. Modern biology will need to develop better metrics
of importance for species and ecosystems to guide our conservation de-
cisions in the context of global climate change.
And we should encourage ecologists and economists to work to-
gether to develop more comprehensive estimates of the value of lost
species and ecosystems even though this is a daunting task.
The short summary on the valuation of impacts on species and eco-
systems is that estimating these impacts is one of the most diffi cult
tasks of all. We have insuffi cient understanding of the risks, and indeed
we do not even know how many species exist in the world today. We
cannot today value ecosystems in a reliable way, nor can we rank them
in terms of their importance.
Moreover, many people feel that strong ethical issues are involved
in extinguishing life. Many feel that humans have a fundamental re-
sponsibility as stewards of planet earth. To allow the sixth mass extinc-
