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Glacial melting { July 19 2002 } Original Source Link: (May no longer be active)
http://www.washingtonpost.com/wp-dyn/articles/A25660-2002Jul18.htmlhttp://www.washingtonpost.com/wp-dyn/articles/A25660-2002Jul18.html
Study Fuels Worry Over Glacial Melting
Research Shows Alaskan Ice Mass Vanishing at Twice Rate Previously Estimated
By Eric Pianin
Washington Post Staff Writer
Friday, July 19, 2002; Page A14
Alaska's glaciers are melting at more than twice the rate previously thought
because of warming temperatures, dramatically altering the majestic contours
of the state and driving up sea levels, according to a new study.
Scientists using highly precise airborne laser measurements of 67 Alaskan
glaciers from the mid-1950s to the mid-1990s discovered that the glaciers
are melting an average of six feet a year -- and in some cases a few hundred
feet -- and that the rate has accelerated in the past seven or eight years.
As one measure of the severity of the problem, the researchers calculated
that the glaciers are generating nearly twice the annual meltage of the
Greenland Ice Sheet, which is the largest ice mass in the Northern
Hemisphere and second only to the Antarctic. That would mean the Alaskan
melt is adding about two-tenths of a millimeter a year to sea levels -- a
seemingly small rise that nevertheless could eventually have long-term
implications for flooding on Pacific islands and along coastal areas, the
researchers concluded.
The study by a team of researchers from the University of Alaska in
Fairbanks, published in today's issue of the journal Science, offers a vivid
and troubling picture of the potential adverse impact of climate change on
the United States and the rest of the world.
"The change we are seeing is more rapid than any climate change that has
happened in the last 10 to 20 centuries," said Keith A. Echelmeyer, one of
the five researchers who prepared the study.
Scientists can't say whether the extraordinary melting is the result of
man-induced global warming, the slow natural advance and rapid retreat of
the glaciers, or dramatic but natural variations in weather patterns. But
the phenomenon is an example of the kind of effects that can occur because
of alterations in the Earth's climate.
"We're getting to the point that this melting is affecting human society,"
said Janine Bloomfield, a climate expert with Environmental Defense, an
advocacy group. "Until now it was just warning signs and signals that the
Earth was warming."
Indeed, the study has provided fresh evidence for Alaskan officials,
researchers and environmentalists who say their state exemplifies the ills
of global warming. Over the past 30 years alone, the annual mean temperature
in Alaska has risen 5.4 degrees Fahrenheit -- four times the average global
increase, according to the University of Alaska's Center for Global Change
and Arctic System Research, an academic research center.
Some scientists theorize that the effects of climate change are most extreme
in the northern part of the Northern Hemisphere because of a quirk in the
way gases and the Earth's radiation get trapped in the atmosphere.
As the state's pervasive permafrost begins to thaw, the consequences are
dramatic and alarming: sagging roads, crumbling villages, sinking pipelines,
the proliferation of insects that are destroying spruce forests and the
possible disruption of marine wildlife. Some Alaskans talk about "drunken
trees" that list and show their roots because of the rapid decline of the
permafrost.
"I see it as a trend that has to be taken seriously," said Gunter Weller of
the Center for Global Change. "If these kinds of occurrences continue . . .
it will have consequences around the world."
However, Sallie L. Baliunas of the Harvard-Smithsonian Center for
Astrophysics in Cambridge, Mass., contends that the Alaskan melting is due
to a dramatic but temporary shift in Pacific Ocean warm water and wind
patterns that began in 1976. "It doesn't have the fingerprints of enhanced
greenhouse gas concentrations," she said.
Sen. Ted Stevens (R-Alaska), who chaired public hearings in Fairbanks last
year on global climate change, said, "Regardless of cause, many changes
predicted worldwide appear to be happening first and with greater severity
in arctic regions, including Alaska."
Past efforts to measure the decline of the Alaskan glaciers have been
imprecise because they were largely based on observations and model
simulations of glacier mass. Glaciers that were monitored routinely were
often chosen more for their ease of access and manageable size than for how
well they represented a given region or how large a contribution they might
make to changing sea level.
The University of Alaska research team -- including Anthony A. Arendt,
William D. Harrison, Craig S. Lingle, Virginia B. Valentine and Echelmeyer
-- used laser devices aboard airplanes to measure the volume and area
changes of the 67 glaciers, representing about 20 percent of the glacial
area in Alaska and neighboring Canada. The profiles developed were compared
with contours on U.S. Geological Survey and Canadian topographic maps made
from aerial photographs taken in the 1950s to early 1970s.
The study found that, during the past five to seven years, glacier thinning
averaged about six feet a year, or twice as fast as that measured on the
same glaciers from the mid-1950s to the mid-1990s. (Because the glaciers are
land-based, their meltage displaces water and pushes up the level of the
ocean.) The annual meltage totaled 52 cubic kilometers and contributed about
9 percent of the observable rise in the sea level over the past
half-century.
"Glaciers in Alaska are thinning quite rapidly . . . and it is due to
climate change," Echelmeyer said. "What we don't know is if it's due to
increased temperature or less snowfall, but it's definitely due to climate
change."
© 2002 The Washington Post Company
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