A paper appearing in the May 15th issue of the journal Nature, co-authored 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 U.S., 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 seagrass 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 for development, whether to curb global fossil fuel consumption in order to limit climate change, all depend on adequately valuing ecosystem services.