GP: Alaska Glacier Melt Surprise

["Tom Gray" <tomgray@igc.org>]

washingtonpost.com

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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