provided by Nature
f we had to pay for the services that nature provides,
how much would it cost?
A paper appearing in the May 15th issue of
the journal Nature, coauthored by 13 ecologists, geographers and
economists, estimates this value at between $16 and $54 trillion per year.
The natural and social scientists who produced
the estimate are affiliated with universities across the United States,
the Netherlands, Sweden and Argentina. The group was organized by Robert
Costanza of the University of Maryland's Institute of Ecological Economics
in College Park. The research was sponsored by the National Science Foundation
(NSF) Center for Ecological Analysis and Synthesis at the University of
California at Santa Barbara.
"Traditionally, ecological concerns have
been considered to be a financial burden on economic development,"
says Scott Collins, director of NSF's long-term ecological research program,
which funds the NSF center. "The study by Costanza and colleagues demonstrates,
however, that ecosystem functions do not compete with economic values. Rather,
they are intimately linked with, and are positive influences on, the global
economy."
The authors of the Nature paper assembled
information from a wide range of studies on the value of a broad range of
ecosystem services. These include not only such familiar items as food production,
raw materials, recreation and water supply, but also services which are
less apparent, like regulation of climate and atmospheric gases, water cycling,
erosion control, soil formation, nutrient cycling and the purification of
wastes.
Estimates were made for each of 17 categories
of services for the range of environments on earth, including both marine
and terrestrial environments. The authors' estimates indicate that coastal
environments, including estuaries, coastal wetlands, beds of sea grass and
algae, coral reefs and continental shelves are of disproportionately high
value. They cover only 6.3 percent of the world's surface, but are responsible
for 43 percent of the value of the world's ecosystem services. These environments
are particularly valuable in regulating the cycling of nutrients which control
the productivity of plants on land and in the sea, according to Costanza.
The researchers note that the majority of the
value from ecosystem services is currently outside the market system. That
is, although some services, such as food production, water supply and raw
materials, are traded in economic markets, most of the world's ecosystem
services are not. "This means that current market signals are not adequately
incorporating the value of these services," says Costanza.
The paper's authors acknowledge the huge uncertainties
involved in their estimate, but also suggest that their values are probably
on the low side. Explains Costanza, "This is because improving the
estimates by, for example, studying more ecosystem services more intensively
would likely increase their value." The authors also caution that their
economic estimates ignore the fact that many ecosystem services are "literally
irreplaceable."
One practical use of the estimates, the authors
write, is to "help modify systems of national accounting to better
reflect the value of ecosystem services and natural capital." Some
attempts to do just that indicate a leveling of national welfare since 1970,
while GNP has continued to increase. "One way to look at it,"
the authors continue, "is that if one were trying to replace the services
of ecosystems, one would need to increase global GNP by at least $33 trillion."
The global GNP is currently about $18 trillion.
A second practical use is for weighing the
ecosystem services lost against the benefits of a particular project or
policy. The paper's authors contend that making good decisions on questions
ranging from whether to drain a local wetland, whether to curb global fossil
fuel consumption in order to limit climate change, all depend on adequately
valuing ecosystem services.
