Climate shift seen possible Researchers cite emissions,
contend world unprepared
By Nick Thompson, Globe Correspondent, 12/12/2001
Releases of carbon dioxide and other so-called ''greenhouse
gases'' could trigger an abrupt and dramatic change in
global temperatures that governments are unprepared to
cope with, according to a new report from the National
Most climate forecasters predict a global temperature
increase of 1 to 6 degrees Fahrenheit over the next century.
But the National Research Council report said history
is full of sudden drops and rises in temperatures, triggered
by environmental changes.
For instance, a sudden change in ocean circulation 13,000
years ago sent temperatures plunging, transforming New
England into a treacherous place to live in a matter of
''Every day could have been a lot like the top of Mount
Washington on the coldest, windiest day of the year,''
says Cameron Wake a climatologist at the University of
Now, scientists at the National Research Council suggest
that the current rapid rise of carbon dioxide in the atmosphere,
due mainly to burning fuels such as oil and coal, could
trigger a new round of rapid heating or cooling.
Scientists have known about that possibility for a long
time, but, according to climatologist Richard Alley, the
chairman of the panel that wrote the report, ''the dangers
hadn't hit us over the head yet.''
The report by one of the nation's most respected scientific
groups will feed the growing debate over what the United
States should do about global warming and potential climate
change. The Bush administration has rejected the global
climate change treaty known as the Kyoto Protocol, which
restricts emissions of carbon dioxide and other heat-trapping
President Bush argues that the treaty would greatly harm
the US economy and place an unfair burden on industrialized
countries by exempting developing nations, particularly
India and China.
The report makes an analogy between the global climate
system and a light switch: a finger slowly presses down,
and suddenly there's a big change when the light goes
off. In the same way, the authors argue, greenhouse gases
could quietly build up in the atmosphere until they cause
a sudden shift in ocean circulation patterns, bringing
heat to some places and a new cold to others.
To be sure, the climate has changed abruptly in the past,
and, even without human influence it almost certainly
will in the future, too. But, according to the report,
titled ''Abrupt Climate Change: Inevitable Surprises,''
pumping the greenhouse gases into the air increases the
likelihood of an abrupt shift.
The danger is that humans seem likely to adapt much better
to slow climate changes. If temperatures go up by a little
bit every year, most trees and animals can migrate to
new regions; farmers can figure out what new crops to
plant; communities near the ocean can prepare for rising
sea levels or more intense and frequent storms. But if
a switch flips and changes come much faster, humans could
face much more difficult problems.
Gary Yohe, an economics professor at Wesleyan College
in Connecticut who helped review the report, said his
biggest fear is that international policy is being made
based on ''smooth climate change.''
The report focuses heavily on the possibility of sudden
climate change caused by disturbing the thermohaline circulation
cycle of the ocean, the system that, when shut down, caused
such cold to come to New England 13,000 years ago.
When working normally, the circulation cycle brings warms
water up from the tropics where it merges with the eastward
moving Gulf Stream and travels up the coast of Europe.
Easterly winds warm up as they blow across the current,
keeping some European cities relatively toasty. Without
this effect, temperate Rome would have a climate very
similar to chilly Boston, because the two cities lie on
the same latitude.
Global warming could disrupt this cycle by melting glaciers
and increasing overall evaporation, which leads to increased
precipitation, changing the density of northern water
and stopping the circulation patterns. That, in turn,
would deliver sudden cold to places such as Western Europe,
and increased heat elsewhere.
Current research suggests that the thermohaline circulation
cycle has already started to slow somewhat, but no one
is certain when and whether it will stop - a prospect
that scares Wake of UNH.
''I really can't imagine how dramatic the changes would
be if we shut down'' thermohaline circulation, he said.
This story ran on page A2 of the Boston Globe on 12/12/2001.
© Copyright 2001 Globe Newspaper Company.
See parts of the report at http://www4.nationalacademies.org/onpi/webextra.nsf/web/climate
This material is distributed by Janet Anderson (USDOJ
5449) on behalf of Pimicikamak Cree Nation. Additional
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