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Showing a Shrinking Ice Cap in Arctic Ocean... ]
Published on Monday, December 23, 2002 in the San Francisco Chronicle
Global Warming Evidence Mounts
Flurry of Reports Show a Withering Ice Cap
by David Perlman
From the tropics to the poles, evidence is growing stronger
than ever that Earth's climate is warming dangerously.
In the Arctic Ocean,
floating masses of sea ice are shrinking
and splitting apart, and the massive Greenland ice cap melted
more this past summer than ever before. Meanwhile, warming ocean
temperatures are endangering coral reefs in the tropics.
At the annual fall
meeting of the American Geophysical Union
in San Francisco earlier this month, a flurry of new reports
examining evidence of global climate change all tell the same
story.
If the trends continue
unchecked, scientists say, rising sea
levels will drown coastlines. Droughts in some regions
-- and increased rainfall in others -- will alter harvests
drastically. And other climate disruptions will destabilize
regional ecologies and global economies.
Some of these alarming
phenomena may be due to the natural
climate variability that the planet has seen over millions
of years. But most scientists agree, after years of debate,
that humans and their addiction to fossil fuels are at least
partly to blame.
"It is humans
who are clearly forcing the abrupt climate
change we see right now," said Richard B. Alley of Pennsylvania
State University, who recently chaired a National Research
Council committee looking specifically at climate change.
So-called greenhouse
gases trap the sun's radiation much
the way glass windows trap heat inside a home or a greenhouse.
The most powerful of those gases is carbon dioxide, which
comes primarily from burning fossil fuel, while other gases
include methane, sulfur dioxide and ozone.
THE BUSH REPORT
A recent NRC report,
which the Bush administration requested
last year when scientists criticized the White House for
its slow response to growing evidence of global warming,
concluded that "human-induced warming" will continue
through
the 21st century.
While it conceded great
uncertainties in the many models of
climate trends that experts have produced, the report predicted
that the planet's climate would warm by 2.5 to 10.4 degrees
Fahrenheit by the century's end due to human activity.
Signs of the striking
pace of that trend came in reports
from many scientists who monitor the ice of the globe's
far north.
The
Arctic's sea ice -- large masses of snow-covered ice
that float everywhere around the polar latitudes -- usually
covers 2.4 million square miles of the ocean north of Canada,
Greenland and Russia in September, the height of the ice season.
This past summer,
however, measurements showed that the
sea ice had decreased by nearly a half-million square miles.
The flat ice floes left wider sections of open water between
them and became extremely thin in many areas, reported
Ted Scambos of the National Snow and Ice Data Center in
Boulder, Colo.
It marked the most
abrupt change in the ocean's ice cover
that scientists monitoring the region have seen in 24 years,
said Mark Serreze of the data center. Records kept
by Icelandic fishermen indicate the cover may not
have been so low for centuries.
"I was really
surprised by the change," Serreze said.
"This was the craziest summer season I've ever seen
up there."
MELTING FASTER
THAN EVER
Equally ominous was
a report by Konrad Steffen, a glaciologist
at the University of Colorado, on Greenland's vast ice cover,
second only in size to Antarctica. It was melting faster this
year across nearly 265,000 square miles than at any period in
recorded history, Steffen said.
The ice sheet is a
mile and a half thick in some places.
As meltwater from the surface seeps through crevices in the
ice, it loosens the edges of the sheet and causes the ice
to flow more swiftly to the sea, where it breaks off into
icebergs.
If
the entire Greenland ice sheet were to completely melt
-- admittedly an unlikely event, at least in the near future
-- then scientists calculate that sea levels would rise by
a globally disastrous 23 feet.
Steffen had a firsthand
experience of the dangers of melting ice.
He and his colleagues were camped on the normally hard-frozen
Greenland ice last June when their camp and equipment were
flooded under a foot of meltwater and they had to be rescued
by helicopter.
The high Arctic is
by no means the only part of the world
where climate change is becoming more dramatic. Scientists
are equally concerned about the impact of changes on tropical
oceans.
KILLING CORAL
Coral reefs are living
creatures. As they die, their calcite
skeletons build up the reefs over millions of years. They are
a crucial part of the world's marine ecosystems, vital to the
productivity of many tropical fisheries.
Most reefs are in shallow
waters near continental and island
coasts, where human-caused destruction is widespread from
coastal pollution, from tourists trampling the reef organisms,
from fishermen ravaging them, and from the hulls of ships
grinding over them.
But five years ago,
the corals in many parts of the world
were afflicted by a mysterious episode of bleaching that
slowed their growth and in many regions killed them outright.
Researchers note that the bleaching has coincided with
increasing ocean temperatures.
"There is growing
agreement that doubling of the carbon
dioxide in the atmosphere means a 15 percent decline in
the coral population," said Robert W. Buddemeier, a senior
chemist with the Kansas Geological Survey, who has studied
the impact of climate change on coral reefs.
"By the end of
the century, with the effects of increasing
levels of carbon dioxide on temperature and on ocean chemistry,
the corals will be in the worst shape we've seen in the
past 50 million years. Things are really dicey," he added.
NO TOUGH MEASURES
The growing evidence
of damage from climate change has
goaded the Bush administration to push its own research
program, although the president does not support any tough
measures to control greenhouse gas emissions, including the
Kyoto Protocol agreed to by most industrialized nations.
Earlier this month,
Assistant Secretary of Commerce James
Mahoney, an atmospheric physicist who is Bush's point man
on global warming, staged a "workshop" in Washington
where
1,500 people from industry, government, academic and
environmental organizations worked on plans for a "strategy
for climate change research."
"There are still
any number of science questions to be
resolved," Mahoney told reporters at the AGU meeting in
San Francisco. He conceded, however, that already "we will
most likely need profound changes in greenhouse gas emissions.
"
But to many analysts,
time is wasting. Global warming
will cause "major political instabilities in the developing
world that could disrupt the global economy," said
Lester R. Brown, founder of the Earth Policy Institute
and a noted environmental analyst who spent 10 years
as a policy adviser in the Department of Agriculture.
FOOD SUPPLY
IMPACT
If measures aren't
taken soon to curb greenhouse gas
emissions, the changes in climate will force rapid changes
in the way the world's food crops are grown. That has
important implications for feeding the world's growing
population, expected to increase to at least 9 billion
by 2050.
"The
vast corn belt of the Northern Hemisphere, for example,
will become hotter and dryer, and that change can't be
resolved merely by creating new corn belts further north,
because the soils further north are not the same at all,"
Brown said.
"Each
global increase of 1 degree Celsius (1.8 degrees
Fahrenheit) around the world will reduce grain yields
like rice and wheat, as well as corn, by at least
10 percent," he said.
And because aquifers
are being tapped at an increasing
pace throughout the world and water tables are falling,
the outcome will soon mean a devastating blow to agriculture
-- particularly in the developing world, he said.
"This disruption
by a combination of climate change and
water shortages has the potential for creating political
instabilities on a scale that we can't even foresee,"
Brown declared.
©2002 San Francisco
Chronicle
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