Thaindian News

Washington, Oct 26 (IANS) Greenland ice sheet can experience extreme melting even when temperatures don?t hit record highs, say scientists.

A new analysis by Marco Tedesco, assistant professor in earth and atmospheric sciences at The City College of New York, suggests that glaciers could undergo a self-amplifying cycle of melting and warming that would be difficult to halt.

?We are finding that even if you don?t have record-breaking highs, as long as warm temperatures persist, you can get record-breaking melting because of positive feedback mechanisms,? said Tedesco, who directs the college’s Cryospheric Processes Lab.

Tedesco and his team collected data this past summer during a four-week expedition to the Jakobshavn Isbrae glacier in western Greenland. Their arrival preceded the onset of the melt season, the college said.

Combining data gathered on the ground with microwave satellite recordings and the output from a model of the ice sheet, Tedesco and graduate student Patrick Alexander found a near-record loss of snow and ice this year.

The extensive melting continued even without last year?s record highs.

The team recorded data on air temperatures, wind speed, exposed ice and its movement, the emergence of streams and lakes of melt water on the surface, and the water?s eventual draining away beneath the glacier.

This lost melt water can accelerate the ice sheet?s slide towards the sea where it calves new icebergs. Eventually melt water reaches the ocean, contributing to the rising sea levels associated with long-term climate change.

The model showed that melting between June and August was well above the average for 1979 to 2010. In fact, melting in 2011 was the third most extensive since 1979, lagging behind only in 2010 and 2007.