Message #187:
From: AzTeC SW Archaeology SIG
To:   "'Matthias Giessler'" 
Subject: Does The Classical Stereotype Hold? -II
Date: Sun, 18 May 1997 22:02:04 -0700

[ follow up to commentary "Does The Classical Stereotype Hold?"
Message 186 -- SASIG Ed. ]

May 17, 1997

A price tag on the planet's ecosystems

by C. Mlot 

It's like trying to audit the books of someone missing a lot of receipts
and bank statements. Yet a group of 13
researchers has pulled together an emerging body of studies on the value
of ecosystems and come up with a
rough figure for the annual worth of Earth's natural goods and services:
$33 trillion.

That includes an estimated value for just about everything under the sun
-- from recreational beaches to
forest lumber to hidden services like the ocean's regulation of
atmospheric carbon dioxide and grasslands'
provisioning for pollinators. A few natural resources were omitted, such
as nonrenewable fuels and
minerals. In comparison to the ecosystems' worth, the researchers report
in the May 15 Nature, the world's
annual gross national products total about $18 trillion.

One goal of the exercise, says Robert Costanza of the Institute for
Ecological Economics at the University of
Maryland in Solomons, is to answer a lingering question in economics:
"Are environmental services big
potatoes or small potatoes? . . . We're saying they're very big

They're probably even bigger than $33 trillion, the researchers and
other observers say. That figure, the
average of calculations ranging from $16 trillion to $54 trillion, comes
from converting and tallying a range
of ecosystem values from more than 100 studies. For example, says
Costanza, data relating the size of
shrimp harvests in Louisiana to the extent of local wetlands were
included in calculations of the average
value of a hectare of wetland, which was then applied to the global
extent of that habitat. Recreational values
came from reports of people's willingness to pay for access to a coral
reef, lake, or other natural area. 

The overall average is conservative because it omits ecosystem services
in several biomes, such as desert and
tundra, that haven't been studied in terms of ecosystem values.
Ecologist Stuart L. Pimm of the University of
Tennessee in Knoxville points out that it also ignores the services in
urban areas, despite the substantial
value of green spaces like New York's Central Park.

The most valuable ecosystems per hectare turn out to be estuaries and
wetlands -- in part, because these
areas have been the object of the most study, says Costanza. Other
ecosystems will probably increase in
value as they are examined more extensively.

The field of ecological economics underlying this analysis is only about
a decade old, and its practitioners
acknowledge its limitations -- the researchers list a dozen caveats to
their study. "We're putting this forth as
a starting point," says Costanza.

It's a reasonable one, says environmental economist Lawrence H. Goulder
of Stanford University. Pimm says
the power of the analysis comes from the per hectare value of habitats
and "the way in which it will inform
local decisions" when it comes to planning.


Costanza, R., et al. 1997. The value of the world's ecosystem services
and natural capital. Nature 387(May

Pimm, S. 1997. The value of everything. Nature 387(May 15):231.


Robert Costanza
Institute for Ecological Economics
University of Maryland
Box 38
Solomons, MD 20688

Lawrence H. Goulder
Department of Economics and Institute for International Studies
Stanford University
Stanford, CA 94305

Stuart L. Pimm
Department of Evolutionary Ecology and Evolutionary Biology
University of Tennessee
Knoxville, TN 37996