http://www.sfgate.com/cgi-bin/article.cgi?file=/chronicle/archive/2003/02/17/MN19885.DTL
February 17, 2003
Earth's temperatures heating up
Averages to rise 8 degrees by end of century,
climate scientist says
David Perlman, Chronicle Science Editor
Denver -- A leading government climate scientist predicted here
Sunday
that average temperatures around the world will rise by as much
as 7 to 8
degrees Fahrenheit before the end of this century -- a major climate
change
that could affect widespread crop fertility and the economies
of many
industrial nations.
The senior scientist did not take sides on the current conflict
between
the United States and the rest of the industrialized world over
mandatory
control of so-called greenhouse gases called for by the 1997 Kyoto
Protocol
which the Bush administration strongly opposes.
But he did contend it is obvious by now that corporate leaders
of U.S.
industries and power plants need to be making serious efforts
to curtail
their emissions of the heat-trapping gases -- principally carbon
dioxide
-- that are affecting climate.
Warren Washington, chief of the Climate Change Research Group
at the
National Center for Atmospheric Research in Boulder, Colo., offered
his
long- range forecast here at the annual meeting of the American
Association
for the Advancement of Science, where climatologists and physicists
are
discussing the various computer models they have created to explain
past
climate changes and the forecast for the near-term future.
"It's clear," Washington
said, "that we're in the midst of a rapidly
changing climate that has accelerated in the past 25 years."
It makes
the last ice age -- an event that ended more than 10,000 years
ago
-- a "mere minor perturbation," he said.
In only the past 25 years, he said, global average temperatures
have
already risen between a third and eight-tenths of a degree, and
pace is
increasing even now, he said.
Scientists have created a wide variety of computer models in
efforts
to understand the many factors that can affect climate, and these
can
include, for example:
Long-term changes in Earth's orbit around the sun which can increase
or
decrease the solar energy that reaches the planet; major natural
events
like volcanic eruptions that can cloud the entire atmosphere with
gases
and ash for centuries, and long-lasting forest fires that can
rage for
years and darken skies with long-lasting soot.
On the basis of the most recent computer models by many groups
-- including
those developed by his own colleagues at Boulder -- Washington
said,
"Scientific confidence in the ability of the models to project
future
climate has increased." Recent experiments as well as routine
monitoring,
he said, "have found evidence of global climate changes already
occurring
that are much larger than can be explained by the climate's natural
variability."
Many scientists have been considering efforts to help rid Earth's
atmosphere
of carbon dioxide by "sequestering" the gas as it emerges
from the plants
that emit it. Some advocate technologies that would scour the
atmosphere
and somehow send the gas deep into the ocean; others believe it
could be
buried deep underground -- in whose back yard, they don't say.
"Sequestering the carbon dioxide burden would slow down
the pace of climate
change appreciably," Washington conceded. "But we also
ought to start cutting
back on emissions as a precautionary principle -- because every
time you
put a single carbon dioxide molecule into the atmosphere, it stays
there
for 900 to 1,000 years or so."
Washington is a 40-year veteran of climate research,
and leads the Boulder
team's development of computer climate models. He is also chairman
of the
National Science Board and has been an adviser on climate issues
to five
presidential administrations, from Jimmy Carter to President Bush.
E-mail David Perlman at dperlman@sfchronicle.com
