Alaskan Glacier Melt Accelerates Sea Level Rise

By Jim Lobe

WASHINGTON, DC, July 19, 2002 (ENS) - In one more piece of evidence that the Earth's climate is warming rapidly, a new study published today in "Science" magazine has found that Alaska's glaciers are melting more quickly than previously believed.

Glaciologists at the University of Alaska Fairbanks Geophysical Institute used an aircraft carrying laser altimetry equipment to survey Alaskan glaciers. (Photo courtesy Science)

"The rate of thinning has doubled in the past five years, compared to the 40 years before," said Anthony Arendt, of the university's Geophysical Institute, the study's main author.

As a result, the Alaskan contribution to sea-level rise has also doubled, to about 0.27 millimeters a year during the past decade, or about twice the amount assumed by an international panel of scientists that last year predicted sea level would rise up to 11 centimeters (4.3 inches) by the end of this century due to global warming.

"It's a big deal if those rates have been underestimated," said Tom Janetos, an expert at the Heinz Center for Science, Economics and the Environment. "If these results are correct, the rate of sea level rise has probably been underestimated in all international assessments."

More than 100 million people live on land within one meter (three feet) of sea level, and storm surges can devastate coral reefs and low-lying islands and coastlines around the world.

"Although some degree of sea level rise is anticipated in the coming decades, the greater the rise and the faster it occurs, the greater the impact will be on human population," said Benjamin Preston, a researcher at the Washington DC based Pew Center on Global Climate Change.

Johns Hopkins Glacier in Glacier Bay, southeast Alaska melts into the sea. (Photo by Commander John Bortniak courtesy NOAA)

A second study published in "Science" today will also add to concerns about the impact on oceans of faster ice melt. Using records compiled over the last 40 years, researchers at Columbia University have found a sharp decline in the salinity of waters in the Ross Sea near Antarctica, as well as warmer air and water temperatures in the area.

The warmer atmosphere appears to have caused more rain and snowfall, less sea ice, and faster melting of the West Antarctic ice sheet, the Columbia scientists say.

Previously, low salinity found in masses of seawater flowing from the Antarctic to the South Pacific was attributed to more precipitation, but the new study confirms that increased melting of the ice cap itself is also a major factor.

Declining salinity could affect major ocean currents, such as the Gulf Stream which warms the waters and climate of the North Atlantic region, according to oceanographers. One prominent theory suggests that a large flow of fresh water into the North Atlantic could reverse the Gulf Stream, as it has in the past, causing an abrupt plunge in water and air temperatures in northeastern North America and northwestern Europe.

Preston said, "If scientists have underestimated the amount of fresh water likely to enter the oceans in coming decades, they may have also underestimated the risk of such a phenomenon occurring."

{Published in cooperation with the OneWorld Network.}