University of Colorado professor Mark Meier, a renowned expert on glaciers, predicts the level of the world's oceans will rise between 7 and 11 inches by the end of this century. His prediction is more than twice that adopted in 2000 by the International Panel on Climatic Change.

Changes in sea level mean big trouble for low-lying coastal communities. Prime real estate would be lost, with profound social and economic consequences.

The dire predictions fuel an already contentious international debate over whether global warming is real, whether it is caused by the accumulation of "greenhouse gases" that trap heat in the atmosphere or whether the global temperature increases and glacial melting are just part of Earth's climatic cycles.

Meier, who presented his findings at the 168th meeting of the American Association for the Advancement of Science, said the International Panel's previous prediction of a sea level increase from 2 inches to 4 inches by century's end was too low for several reasons, the most important of which was underestimating the effects of the disappearance of glaciers in the Alps, southern Alaska and the Patagonian mountains of South America.

Recent measurements by aircraft using global positioning satellites and laser altimeters show that the 5,000-square-kilometer Malaspina glacier in Alaska is losing nearly a meter of thickness per year -- the equivalent of 3 cubic kilometers of water. That glacier alone has 10 times the water of all the glaciers in the Alps, which have shrunk to half their ice volume since the 1850s.

While climatologists have focused their attention on the great ice sheets of Greenland and Antarctica for signs of melting that could raise sea levels, Meier said the impact of "smaller" glacial melting has been underestimated.

"In many environments, the 'little' glaciers are disappearing," he said. "In 20 years, you'll be able to visit 'Non-Glacier National Park' (in Montana). If you want to see the snows on Kilimanjaro, you'd better go soon."

Meier said that earlier predictions did not take into account that small glaciers melt much faster than large ones, and that while most of the largest glaciers are not yet losing mass to melting, they will if trends continue.

Outside of Greenland and Antarctica, all the smaller glaciers of the world contain enough water to raise ocean levels nearly 20 inches, according to Meier.

Sea level increases are driven by both water temperature -- warmer water is less dense and so it takes up more space -- and by the melting of glaciers' ice.

Research continues to show a maddening mix of messages on polar warming.

While global temperatures have increased since the 1970s, the latest temperature increases are smaller than experienced between the 1920s and 1940s.

"Warming patterns are not unprecedented in the instrumental record," said Mark Serreze, another University of Colorado expert on cold climates.

There is clear evidence of glacial melting, and, in the Northern Hemisphere, signs that the line of permafrost -- where soil is frozen year-round -- is migrating north.

A University of Washington study of data from Cold War era submariners found that the Arctic Sea ice has thinned an astonishing 40 percent since the 1960s. Yet a new study of the same phenomenon found there has been very little thinning since 1990.

In Antarctica, there is clear evidence of ice shelf break-up and warmer temperatures on some sections of the continent, yet in others temperatures remain cold, and satellite measurements show a trend to more sea ice since 1977.

Claire Parkinson, a climatologist at NASA's Goddard Space Flight Center in Maryland, reported that during the same period, the area of sea ice in the Arctic was decreasing by 13,000 square miles a year -- an icepack the size of Maryland and Delaware.

But other satellite readings suggest that the phenomenon might be driven by a cyclic weather pattern known as the North Atlantic Oscillation.

Despite the need for research and the high stakes, financial interests in Canada, the United States and Russia are curtailing the number of staffed research stations on the Arctic coast that could provide ice measurements.

"A lot of monitoring activity is going down the tubes, and we need data more than ever," Meier said.

©2002 San Francisco Chronicle

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