New
Climate Report Too Rosy, Experts Say
By Seth Borenstein
31 January, 2007
Associated
Press
Later this week in Paris, climate
scientists will issue a dire forecast for the planet that warns of slowly
rising sea levels and higher temperatures. But that may be the sugarcoated
version.
Early and changeable drafts
of their upcoming authoritative report on climate change foresee smaller
sea level rises than were projected in 2001 in the last report. Many
top U.S. scientists reject these rosier numbers. Those calculations
don't include the recent, and dramatic, melt-off of big ice sheets in
two crucial locations:
They "don't take into
account the gorillas — Greenland and Antarctica," said Ohio
State University earth sciences professor Lonnie Thompson, a polar ice
specialist. "I think there are unpleasant surprises as we move
into the 21st century."
Michael MacCracken, who until
2001 coordinated the official U.S. government reviews of the international
climate report on global warming, has fired off a letter of protest
over the omission.
The melting ice sheets in
Greenland and Antarctica are a fairly recent development that has taken
scientists by surprise. They don't know how to predict its effects in
their computer models. But many fear it will mean the world's coastlines
are swamped much earlier than most predict.
Others believe the ice melt
is temporary and won't play such a dramatic role.
That debate may be the central
one as scientists and bureaucrats from around the world gather in Paris
to finish the first of four major global warming reports by the Intergovernmental
Panel on Climate Change. The panel was created by the United Nations
in 1988.
After four days of secret
word-by-word editing, the final report will be issued Friday.
The early versions of the
report predict that by 2100 the sea level will rise anywhere between
5 and 23 inches. That's far lower than the 20 to 55 inches forecast
by 2100 in a study published in the peer-review journal Science this
month. Other climate experts, including NASA's James Hansen, predict
sea level rise that can be measured by feet more than inches.
The report is also expected
to include some kind of proviso that says things could be much worse
if ice sheets continue to melt.
The prediction being considered
this week by the IPCC is "obviously not the full story because
ice sheet decay is something we cannot model right now, but we know
it's happening," said Stefan Rahmstorf, a climate panel lead author
from Germany who made the larger prediction of up to 55 inches of sea
level rise. "A document like that tends to underestimate the risk,"
he said.
"This will dominate
their discussion because there's so much contentiousness about it,"
said Bob Corell, chairman of the Arctic Climate Impact Assessment, a
multinational research effort. "If the IPCC comes out with significantly
less than one meter (about 39 inches of sea level rise), there will
be people in the science community saying we don't think that's a fair
reflection of what we know."
In the past, the climate
change panel didn't figure there would be large melt of ice in west
Antarctica and Greenland this century and didn't factor it into the
predictions. Those forecasts were based only on the sea level rise from
melting glaciers (which are different from ice sheets) and the physical
expansion of water as it warms.
But in 2002, Antarctica's
1,255-square-mile Larsen B ice shelf broke off and disappeared in just
35 days. And recent NASA data shows that Greenland is losing 53 cubic
miles of ice each year — twice the rate it was losing in 1996.
Even so, there are questions
about how permanent the melting in Greenland and especially Antarctica
are, said panel lead author Kevin Trenberth, chief of climate analysis
at the National Center for Atmospheric Research in Colorado.
While he said the melting
ice sheets "raise a warning flag," Trenberth said he wonders
if "some of this might just be temporary."
University of Alabama at
Huntsville professor John Christy said Greenland didn't melt much within
the past thousand years when it was warmer than now. Christy, a reviewer
of the panel work, is a prominent so-called skeptic. He acknowledges
that global warming is real and man-made, but he believes it is not
as worrisome as advertised.
Those scientists who say
sea level will rise even more are battling a consensus-building structure
that routinely issues scientifically cautious global warming reports,
scientists say. The IPCC reports have to be unanimous, approved by 154
governments — including the United States and oil-rich countries
such as Saudi Arabia — and already published peer-reviewed research
done before mid-2006.
Rahmstorf, a physics and
oceanography professor at Potsdam University in Germany, says, "In
a way, it is one of the strengths of the IPCC to be very conservative
and cautious and not overstate any climate change risk."
Copyright © 2007 Associated
Press
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