Rainforests Might Help Slow Global Warming
10/16/98
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RELAYED TEXT STARTS HERE:
Title: Rainforests Might Help Slow Global Warming
Source: Science (vol. 282, pp. 439-442)
William F. Laurance, Ph.D.,
Email: wfl@inpa.gov.br
Status: Copyrighted, contact source to reprint
Date: 10/16/98
RAINFORESTS MAY HELP SLOW GLOBAL WARMING
Manaus, Brazil: Scientists working in the Amazon and Central America have
been stunned to discover that undisturbed rainforests there are apparently
growing faster--and in doing so, may be acting as massive sponges for
carbon dioxide and other greenhouse gases.
This discovery, reported this week in the journal Science (16 October),
may not only help solve a long-standing scientific mystery, but could have
crucial implications for the environment and earth's changing climate.
Atmospheric pollutants such as carbon dioxide have grown steadily since
the industrial revolution began two centuries ago. Carbon dioxide has
increased by a third and is still rising, fueled by industrial emissions,
car exhausts, and the rapid clearing and burning of tropical forests.
Most scientists agree that significant global warming--the greenhouse
effect--is likely to result.
But scientists have been puzzled because levels of carbon dioxide should
be rising even faster than they have been. "When you add up all the
sources of pollution, such as fossil-fuel and forest burning, you should
actually get a lot more carbon dioxide in the air," said Yadvinder Malhi,
a British member of the research team. "Something seems to be sucking up
millions of tons of carbon dioxide each year."
Now it seems that the mystery of the "missing" carbon dioxide may be
solved--at least partially. Working throughout South and Central America,
the research team compiled data from studies of over 100,000 trees over
the past 30 years. In most of their study plots, they found that the
forests have become more massive.
"Our results suggest that over the past three decades, the living trees in
each acre of rainforest have gained over 17 tons," said Oliver Philips,
another British team member. "Each acre would have to absorb an
additional 20 tons of carbon dioxide to increase that much."
And that is an impressive figure. In the Amazon Basin alone, the
scientists estimate that intact rainforests could be absorbing over a
billion tons of carbon dioxide each year--enough to account for a big
chunk of the "missing" carbon dioxide.
But why are the forests getting bigger? Ironically, the team believes a
likely cause is the increasing carbon dioxide itself. "Plants need carbon
dioxide to grow, and when it's more abundant they often grow faster--just
like adding fertilizer," said Dr Phillips. Another possibility is that
extra nutrients are raining down on the forests as other areas of forest
are burned.
While welcome news for the environment, the scientists caution that the
forest's capacity to absorb carbon dioxide is rapidly diminishing. "It's
vital to emphasize that only undisturbed rainforests are absorbing extra
carbon dioxide," said William Laurance, a U.S. team member. "When you
burn, log, or fragment the forests, you ruin the beneficial effects and
dump even more carbon dioxide into the atmosphere--and we're destroying 40
million acres of rainforest a year."
For comments and interviews, contact:
Dr William Laurance
Smithsonian Institution and National Institute for Research in the Amazon
Manaus, Brazil
Phone: 55-92-642-1148 (w); 55-92-644-2153 (a/h) Fax: 55-92-642-2050
Email: wfl@impa.gov.br
Dr Yadvinder Malhi (from Oct. 9-14 and after Oct. 29) Institute of Ecology
and Resource Management University of Edinburgh
Edinburgh, U.K.
Phone: 44-131-650-5744 (w)
Fax: 44-131-662-0478
Email: ymalhi@ed.ac.uk
Dr Oliver Phillips (after Oct. 20)
Department of Geography
University of Leeds
Leeds, U.K.
Phone: 44-1132-336832
Fax: 44-1132-333308
Email: oliverp@geog.leeds.ac.uk
William F. Laurance, Ph.D.,
Senior Research Scientist
National Institute for Research in the Amazon (INPA) C.P. 478
Manaus, AM 69011-970
BRAZIL
Email: wfl@inpa.gov.br
Fax: 55-92-642-2050
Ph: 55-92-642-1148