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Greenland Glacier Acceleration Levels Less Than Originally Feared

May 4, 2012
Image Caption: These icebergs recently calved from the front of the north branch of Jakobshavn Isbrae, a large outlet glacier that drains 6.5 percent of the Greenland ice sheet. The fact that they are upright, indicated by their dirty and crevassed surfaces, suggests they calved from the floating end of a glacier. Credit: Ian Joughin/UW

Some of Greenland’s glaciers are moving approximately 30% faster than they were a decade ago, contributing to the rising sea level but not reaching worst-case speed levels that experts once feared, a new study published in Friday’s edition of the journal Science has discovered.

According to Reuters reporter Deborah Zabarenko, researchers at the University of Washington (UW) and Ohio State University (OSU) studied satellite data from 2000 to 2011. They focused on more than 200 glaciers and discovered that their acceleration levels were not increasing as rapidly as earlier projections had feared.

Previously, scientists analyzing the issue had presented a scenario in which the Greenland glaciers would double their velocity between 2000 and 2010, then stabilizing in terms of speed, as well as a second scenario in which their speeds would increase tenfold before stabilizing.

Under the first scenario, the sea level would rise by approximately four inches by 2100, and under the second, it would increase by nearly 19 inches by that time, the University of Washington said in a May 3 press release.

However, as they point out, those researchers “had little precise data available for how major ice regions, primarily in Greenland and Antarctica, were behaving in the face of climate change.”

For the new study, lead author Twila Moon, a University of Washington doctoral student in Earth and space sciences, and co-authors Benjamin Smith of the UW Applied Physics Laboratory and Ian Howat, an assistant professor of earth sciences at OSU, recorded annual, wintertime changes in the outlet glaciers by using data from the Canadian Space Agency‘s Radarsat-1 satellite, Germany’s TerraSar-X satellite and Japan’s Advanced Land Observation Satellite, and discovered lower-than-anticipated increased in velocity.

“´Glacial pace´ is not slow anymore,” Moon told the Associated Press (AP). That said, she added that, “some of the worst-case possibilities that we had imagined are not coming true at this point. So it´s not good news, but it´s not bad news.”

“There’s the caveat that this 10-year time series is too short to really understand long-term behavior,” Howat added in the UW press release. “So there still may be future events — tipping points — that could cause large increases in glacier speed to continue. Or perhaps some of the big glaciers in the north of Greenland that haven’t yet exhibited any changes may begin to speed up, which would greatly increase the rate of sea level rise.”

NASA and the National Science Foundation (NSF) funded the research.

“We don’t have a really good handle on it and we need to have that if we’re going to understand the effects of climate change,” said Moon, who said she was inspired to participate in the study out of a desire to collect the satellite data and compile it into a usable form to analyze exactly what is happening to Greenland’s glaciers. “We are going to need to continue to look at all of the ice sheet to see how it’s changing, and we are going to need to continue to work on some tough details to understand how individual glaciers change.”


Source: RedOrbit Staff & Wire Reports



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