Scientists detail signs of Arctic warming
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Scientists detail signs of Arctic warming
By SAM BISHOP News-Miner Washington Bureau
WASHINGTON--Scientists described thinning sea ice, warming
permafrost, expanding shrubs on the tundra and other signs of Arctic
warming for an audience in a U.S. Senate hearing room on Tuesday,
then encouraged congressional staff to call when they need
information on the subject.
"There isn't a scientist I know who isn't pleased to answer
questions," said Matthew Sturm, a researcher at the U.S. Army Cold
Regions Research and Engineering Laboratory in Fairbanks.
Sturm and three scientists from universities around the country
offered to share basic information with members of Congress who are
puzzling through what policies the federal government should adopt in
response to the warming.
The presentation Tuesday wasn't part of an official hearing. Rather,
it was an informal "congressional briefing," an avenue frequently
used by groups trying to spread a message on Capitol Hill.
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Tuesday's event was sponsored by the Fairbanks-based Arctic Research
Consortium of the United States, which promotes communication and
collaboration among northern scientists. The group's annual meeting
begins today in Washington, D.C., and will feature not only
scientific presentations but also speeches from Sen. Lisa Murkowski,
R-Alaska, and former Lt. Gov. Fran Ulmer, now with the University of
Alaska Anchorage's Institute of Social and Economic Research.
The meeting comes as members of Congress debate what actions, if any,
the government ought to take to reduce human production of gases such
as carbon dioxide that scientists say contribute to Earth's warming.
On Friday, Rep. Don Young, R-Alaska, voted with other members of the
House to remove a statement from a spending bill that attributed
global warming to humans. On Tuesday, Murkowski voted in the Senate
Foreign Relations Committee for an amendment encouraging the
administration to participate in negotiations under the United
Nations Framework Convention on Climate Change to, in part, reach "a
significant long-term reduction in global greenhouse gas emissions."
Mark Serreze, with the University of Colorado at Boulder's National
Snow and Ice Data Center, gave the audience at Tuesday's
congressional briefing a quick overview of the Arctic warming signs,
using charts and graphs of the latest science:
* The Greenland ice sheet, while thickening in the center and gaining
slightly in total mass recently, has been thinning on the edges due
to melting, he said. Also, the increased meltwater may
be "lubricating" the base of the ice sheets, causing them to flow
toward coasts more rapidly.
* Permafrost temperatures measured near Teshekpuk Lake on Alaska's
North Slope, while still well below freezing, increased by about 7
degrees Fahrenheit from 1977 to 2005.
* Tundra shrubs are growing larger and more abundant.
* Sea ice cover on the Arctic Ocean was the lowest ever measured both
in September of 2005 and last month.
Charles Vorosmarty of the University of New Hampshire explained how
some of these changes are self-reinforcing. Sea ice reflects about 85
percent of the sun's energy, while open water reflects only about 10
percent. Tundra reflects about 80 percent while forest reflects just
20 percent, he said. Thus, the physical and organic changes that
occur with warming can "conspire to create a strong feedback," he
Serreze, after the presentation, said the existence of past ice ages
obviously demonstrates that some climatological factor is able to
overcome such a warming feedback.
That factor, he said, is apparently the reduction in incoming energy
that takes place when two things occur at the same time: The Earth
reaches the farthest distance from the sun in its orbit, and the
Earth's axis, which wobbles a bit over time, is less tilted toward
the sun on the northern end.
Those two astronomical phenomena won't occur simultaneously for
another 10,000 years, Serreze said. "So that's not going to save us"
from the present warming, he said.
The sun has also grown slightly brighter in recent years, Serreze
noted, and if it dimmed, it might reduce the amount of energy driving
the Earth's warming. But the energy arriving from the sun's increased
brightness is much less than the increased energy that has been
trapped by growing levels of carbon dioxide in the atmosphere, he
Volcanoes can also cool the atmosphere, but their effects are
occasional and short-lived, he said.
Serreze said the only realistic change that could combat the warming
trend would be a reduction in atmospheric carbon dioxide. Carbon
dioxide molecules now make up about 380 parts of every million parts
of air. That's well above other peaks from the past 400,000 years,
all of which topped out at less than 300 ppm, according to analysis
of air bubbles in ancient ice sheets.
Other scientists, including Syun-Ichi Akasofu, director of the
International Arctic Research Center in Fairbanks, have said that
it's still unclear how much humans have contributed to the trend.
Akasofu warned senators in a recent hearing against actions that
could have severe economic consequences with little reward.
Akasofu said he is still unsure of the human impacts in part because
global computer models, when fed historical data, do not reliably
forecast what actually has happened across wide regions.
Serreze acknowledged that scientists are still struggling to find
models that are able to match specific regional variations.
"Right now our ability to make those predictions with our current
models is less than optimal," Serreze said.
Vorosmarty noted, though, that when historic data on temperature
increases, vegetation changes, sea ice reductions and ocean dynamics
are all fed into global climate models, the computers predict a
warming trend in the higher latitudes that generally reflects what
scientists are measuring today.
The scientists also warned that change could happen very rapidly if
various factors push the climate over a tipping point.
Sturm noted that the Laurentide ice sheet, which 20,000 years ago
covered all of Canada and many of the northern U.S. states, grew very
slowly. "It went away very fast," Sturm said.
Washington, D.C., reporter Sam Bishop can be reached at (202) 662-
8721 or sbishop@... .