By Jeremy van Loon
Jan. 29 (Bloomberg) -- Glaciers from the Andes to Alaska and across
the Alps shrank as much as 3 meters (10 feet), the 18th year of retreat
and twice as fast as a decade ago, as global warming threatens an
important supply of the world's water.
Alpine glaciers lost on average 0.7 meters of thickness in 2007, the
most recent figures available, data published today by the University of
Zurich's World Glacier Monitoring Service showed. The melting extends an
11-meter retreat since 1980.
"One year doesn't tell us much, it's really these long-term trends
that help us to understand what's going on," Michael Zemp, a researcher
at the University of Zurich's Department of Geography, said in an
interview. "The main thing that we can do to stop this is reduce
greenhouse gases" that are blamed for global warming.
The Alps have suffered more than other regions with half of the
region's glacier terrain having disappeared since the 1850s, Zemp said.
Almost 90 percent of the glaciers in the Alps are smaller than 1 square
kilometer (0.4 square mile) and some are as thin as 30 meters, he said.
Some maritime glaciers, or those that terminate in the sea, have
grown in recent years, including 2007, Zemp said. They include glaciers
at Nigardsbreen, Norway, and Alaska that were helped by temperatures
that remain below freezing and ample snow.
Glaciers further inland in Alaska in such sites as the Kenai
mountains and Scandinavia matched the overall declining trend seen in
Chile, Colombia and throughout the Alps.
The World Glacier Monitoring Program has measured 30 glaciers, of an
estimated 150,000 to 200,000 worldwide, in nine mountain ranges since
1980. More ice has been lost than gained on average in 25 of the past 28
years with the last year of growth reported in 1989, when the Berlin
Wall was dismantled and Communist regimes fell across eastern Europe.
Glacier loss is measured by hammering poles into the ice sheet and
observing how much the ice has retreated or gained against the measuring
rod. Calculations are made too at the tongue or end of the glacier while
satellite technology is also employed, Zemp said.
The pace of the decline has doubled since the 1990s, when the average
loss was about 0.3 meters compared with 0.7 meters now, he said.
Glaciers at high altitudes and latitudes, such as Switzerland's Aletsch
and the Devon Ice Cap in Canada, would likely survive a global
temperature increase of 3 degrees.
Some glaciers in the Alps, including Italy's Calderone, have shrunk
so much it's becoming difficult to take accurate measurements, Zemp
said. Such ice has not recovered from the 2003 European summer heat wave
that melted the snow, revealing darker ice underneath which heats up
faster than whiter surfaces.
The global average temperature has risen 0.76 degrees Celsius (1.4
degrees Fahrenheit) since pre-industrial times as humans used more
fossil fuels to generate energy and power machinery, according to the
UN's Environment Program.
Ice melt is even speeding in Greenland. In 2007, U.S. scientists
discovered that water from melting glaciers, draining from a 5.6
square-kilometer lake on Greenland's ice sheet, reached a peak flow
exceeding that of Niagara Falls.
There are gaps in data for many glaciers in the Himalayas, Zemp
added. Central Asia has been highlighted by the UN's Environment Program
as being most at risk from melting glaciers as China and India, home to
a third of the world's population, depend on summer melted water from
mountain ice to feed rivers.
India's Chhota Shigri and Hamtah glaciers both lost about 1.4 meters
of thickness in 2006 with no new data available for 2007, according to
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