Is Taking More
Than Earth Can Give
The Planet Is Ecologically Overburdened By 20 Percent
Carl T. Hall
doubts that people put a heavy burden on the biosphere.
Now, a global team of ecology experts, working under the
sponsorship of famed Harvard biologist Edward O. Wilson,
has tried to weigh just how heavy the load might be.
bottom line is a single, sobering number: 120 percent.
up all the farming, fishing, mining, building and fuel
consumption, researchers calculated our global ecological
demand to be the equivalent of 120 percent of the Earth's
capacity to sustain these activities.
20 percent beyond the break-even point means that "it
would require 1.2 Earths, or one Earth for 1.2 years,
to regenerate what humanity used in 1999," the researchers
conclude in a study appearing today in the Proceedings
of the National Academy of Sciences. The analysis is based
on 1999 statistics, the most recent available, and generally
accepted estimates of the planet's biological productivity.
"ecological overshoot" started in the late 1970s
and continues to widen, the researchers added. During
an interview Monday, Wilson said the new study offered
one of the first impartial methods of keeping tabs on
is a very effective measure for telling the world where
we are and what the trajectory might be," Wilson
said. "We've never really had anything like this
before -- a measure we can intuitively understand and
that's based on solid data."
study is also one of the latest attempts by ecology specialists
to use some of the standard tools of economics, transforming
fisheries, forests and other key elements of the biosphere
into so much "natural capital."
idea is to monitor the ebbs and flows of this form of
capital with much the same kind of numerical rigor that
economists use in tracking labor, investment and industrial
need accounts for our use of nature, the same as we use
accounts in business," said Mathis Wackernagel, program
director at the Oakland-based group Redefining Progress
and lead author of the new study.
include Norman Myers of Oxford University, Jorgen Randers
at the Norwegian School of Management and Richard Norgaard
at UC Berkeley.
authors shied away from any specific policy choices that
might reduce the shadow cast by humanity's huge "ecological
footprint." But they made it clear that in their
view current consumption patterns could not be sustained.
the average amount of productive land needed to satisfy
the needs and wants of each man, woman and child is about
2.3 "global hectares" -- the standardized measure
of productive acreage used by the study authors. By comparison,
the productive capacity of the Earth is estimated at 1.9
hectares per capita.
imbalance is much more pronounced, of course, in the richest
countries: The United States, for instance, consumed about
9.7 global hectares per person for 1999, while the United
Kingdom commanded 5.4, and Germany took 4.7.
are overspending," Wackernagel said, calling the
trend a prescription for "ecological bankruptcy"
that is starting to show up already in collapsing commercial
fisheries, loss of productive cropland and demise of natural
conservative critics said the study amounted to little
more than fancy guesswork, saying there were no data to
justify the implication that human activity was running
roughshod over the planet's health.
think this is another one of these scare tactics"
from environmentalists, said Thomas Gale Moore of the
Hoover Institution in Palo Alto. "They come to the
conclusion that mankind is already using 120 percent of
the Earth's capacity. But if that were true, I would think
we'd be seeing a general degradation of the world, when
in fact the environment, certainly in the advanced countries
of the world, is getting cleaner and better, not dirtier."
new study drew mostly from national production and land-use
statistics already being prepared by governments around
the world. In the new framework, these statistics become
fodder for a kind of "ecological GDP" -- a single
number to sum up all the best available "biophysical
indicators" to track resources and the sustainability
of the human economy.
purpose of these global accounts is not merely to illustrate
a method for measuring human demand on bioproductivity,
but to offer a tool for measuring the potential effect
of remedial policies," the authors conclude.
what form those policies might take is a matter the researchers
are leaving to policymakers to decide. They said any such
decisions were being made in a vacuum without some fair
way to keep score.
like the one presented here allow humanity, using existing
data, to monitor its performance regarding a necessary
ecological condition for sustainability: the need to keep
human demand within the amount that nature can supply,"
the study stated.
Carl T. Hall at: mailto:email@example.com