Earth's Ice Melting Faster Than Projected by Lester R. Brown

EARTH'S ICE MELTING FASTER THAN PROJECTED

Lester R. Brown

Several new studies report that the Earth's ice cover is melting faster than projected by the international Intergovernmental Panel on Climate Change (IPCC) in its 2001 report. Among other things, this means that the IPCC team, which did not have the ice melt data through the 1990s, will need to revise upward its projected rise in sea level for this century—currently estimated to range from 0.09 meters to 0.88 meters (from 4 to 35 inches).

A study by two scientists from the University of Colorado's Institute of Arctic and Alpine Research shows that melting of the large glaciers on the west coast of Alaska and in northern Canada is accelerating. The new data for the 1990s indicate that the more rapid melting is now raising sea level by 0.32 millimeters a year, more than twice as fast as earlier data indicated.

The Colorado study is reinforced by a U.S. Geological Survey (USGS) study, which indicates glaciers are now shrinking in all 11 of Alaska's glaciated mountain ranges. An earlier USGS study reported that the number of glaciers in Glacier National Park in the United States has dwindled from 150 in 1850 to fewer than 50 today. They project the remaining glaciers will disappear within 30 years.

Another team of USGS scientists, which uses satellite data to measure changes in the area covered by glaciers, describes an accelerated melting of glaciers in several mountainous regions, including the South American Andes, the Swiss Alps, and the French and Spanish Pyrenees.

Glaciers are shrinking faster throughout the Andes. Located on the west side of the Quelccaya ice cap in the Peruvian Andes, the Quri Kalis glacier's annual shrinkage from 1998 to 2000 was three times that which occurred between 1995 and 1998. And that, in turn, was nearly double the annual rate of retreat from 1993 to 1995. The large Quelccaya ice cap is projected to disappear entirely between 2010 and 2020.

The vast snow/ice mass in the Himalayas, which ranks third in fresh water stored, after Antarctica and Greenland, is also retreating. Kilimanjaro, which has lost 33% of its ice field, is projected to disappear entirely within the next 15 years.

Both the North and the South Poles are showing the effects of climate change. The Antarctic ice sheet, which is 1.5 miles thick in some places, contains over 90% of the world's fresh water. While this vast ice sheet is relatively stable, the ice shelves—the portions of the ice sheet that extend into the surrounding seas—are fast disappearing, evidenced by the recent collapse of the Larsen B ice shelf on March 7.

Over the last 35 years, the Arctic Sea ice has thinned 42%—from an average of 3.1 meters to 1.8 meters. It has also shrunk by 6% since 1978. A team of Norwegian scientists projects that the Arctic Sea could be entirely ice-free during the summer by mid-century, if not before.

If this melting materializes as projected, the early explorers' dream of a Northwest Passage—a shortcut from Europe to Asia—could be realized. Unfortunately, what was a dream for them could be a nightmare for us.

If the Arctic Ocean becomes ice-free in the summer, it would alter the regional heat balance. Richard Kerr, writing in Science, says summer “would convert the Arctic Ocean from a brilliantly white reflector sending 80% of solar energy back into space into a heat collector absorbing 80% of [incoming sunlight].”

The accelerated melting of ice, particularly during the last decade or so, is consistent with the accelerating rise in temperature that has occurred since 1980. With the IPCC projecting global average temperature to rise by 1.4 to 5.8 degrees Celsius (2.5 to 10.4 degrees Fahrenheit) during this century, the melting of ice will likely continue to gain momentum.

Our generation is the first to have the capacity to alter the Earth's climate. We are also, therefore, the first to wrestle with the ethical question of whether the capacity to change the planet's climate gives us the right to do so.

For the full report go to http://www.earth-policy.org/Updates/Update8.htm
Lester R. Brown is the President of the Earth Policy Institute.