NASA scientists reading signals from a satellite in orbit, and flying aboard a low-flying plane over Greenland, are finding fresh evidence of melting snows and thinning glaciers in vast areas of the massive island.
Their observations confirm the climate’s warming trend in the far northern reaches of the world, they say, where changes in the circulation of waters feeding into the Arctic Ocean are altering crucial patterns of ocean currents there with effects that are increasingly uncertain.
The pace of glaciers sliding into the sea along Greenland’s southwestern coast “is speeding like gangbusters this year,” said William Krabill, leader of a NASA team that has just ended a three-week airborne mission probing glacier dynamics with lasers and radar.
In similar flights seven years ago, he recalled, data gathered by instruments aboard the plane showed that glaciers were moving into the ocean at a rate of about 6 feet a year. But seven flights this spring, covering 16,000 miles of Greenland’s surface and coastal glaciers, revealed that ice along the southern coast is speeding to the sea at more than 75 feet a year, Krabill said.
And while the glaciers are on the move, Greenland’s snows have been melting over large areas of the ice sheet, according to Marco Tedesco, a research scientist at NASA’s Goddard Space Flight Center who has been working on a joint climate study project with the University of Maryland.
Data from a Defense Department meteorology satellite show that last spring the snow on Greenland melted over an area of more than 375,000 square miles – nearly 21/2 times the surface area of California, Tedesco said Friday. That was far more than the island’s average summertime snowmelt area of 350,000 square miles, he said.
The satellite data also showed that last summer the island experienced more days of melting snow and at higher altitudes than the average of all the past years, he said.
Melting snow is more significant than just another indicator of global warming, both Tedesco and Krabill said, for in many areas near the coast the water can drain through surface cracks and vertical passages inside the glaciers and reach bedrock where it lubricates the ice sheet and speeds the flow of the glaciers to the ocean.
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