June 19, 2013
Greenland glaciers speed up, swelling rising seas
Some of Greenland's glaciers are moving about 30 percent faster than they did 10 years ago, contributing to rising global sea levels, but that still may not be enough to reach the most extreme projections for 2100, scientists reported on Thursday.
Researchers have been monitoring the big ice sheets of Greenland and Antarctica for decades as one indication of the impact of human-spurred climate change.
Made of compacted snow, these glaciers can move toward the sea, and when they get there, they dump water into the oceans around them. The faster they move, the more water they add, and the higher the oceans get.
Not all glaciers move at the same pace, according to Twila Moon and her co-authors at the University of Washington and Ohio State University, whose research is published in the current issue of the journal Science.
Inland glaciers with no outlet to the sea poke along at top speeds of 30 to 325 feet (9 to 99 metres) a year, the researchers found, while those that end at the ocean can travel 7 miles (11.2 km) a year.
The glaciers that flow to the sea around Greenland are the ones to watch, Moon said in a telephone interview, because that is where four-fifths of the loss of ice in Greenland occurs.
Satellite surveys of more than 200 glaciers showed that these comparatively fast-movers in the east, southeast and northwest areas of Greenland increased their speed by an average of 30 percent from 2000 to 2011.
The researchers found that the glaciers heading for the water were not accelerating as much as had been speculated in earlier projections of the worst that could happen. Based on those projections, there was a previous forecast of sea level rise of about 6 feet (2 metres) by century's end.