Glaciers around the world found shrinking for 18th year
Researchers say pace of retreat is quickening
BERLIN - Glaciers from the Andes to Alaska and across the Alps shrank as much as 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, data published yesterday 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 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.
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 probably survive a global temperature increase of 3 degrees.
Some glaciers in the Alps 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 1.4 degrees since preindustrial times, according to the UN's Environment Program.