Warm ocean currents cause ice loss from Antarctica
April 26th, 2012 - 3:23 pm ICT by IANSWashington, April 26 (IANS) Warm ocean currents attacking the underside of ice shelves may help explain recent ice loss from Antarctica, says a new study.
A team of scientists used measurements from NASA’s Ice, Cloud, and land Elevation Satellite (ICESat) and models to differentiate between the two known causes of melting ice shelves: warm ocean currents thawing the underbelly of the floating extensions of ice sheets and warm air melting them from above.
The finding brings scientists a step closer to providing reliable projections of future sea level rise. The researchers concluded that 20 of the 54 ice shelves are being melted by warm ocean currents.
Most of these are in West Antarctica, where inland glaciers flowing down to the coast and feeding into these thinning ice shelves have accelerated, draining more ice into the sea and contributing to sea-level rise, according to a statement of the British Antarctic Survey.
This ocean-driven thinning is responsible for the most widespread and rapid ice losses in West Antarctica, and for the majority of Antarctic ice sheet loss during the study period.
“We can lose an awful lot of ice to the sea without ever having summers warm enough to make the snow on top of the glaciers melt,” said Hamish Pritchard of the British Antarctic Survey in Cambridge, UK, who led the study. “The oceans can do all the work from below.”
To map the changing thickness of almost all the floating ice shelves around Antarctica, the team used a time series of 4.5 million surface height measurements taken by a laser instrument mounted on ICESat from October 2003 to October 2008.
“This study demonstrates the power of space-based, laser altimetry for understanding Earth processes,” said Tom Wagner, cryosphere programme scientist at NASA Headquarters in Washington.
ICESat was the first satellite specifically designed to use laser altimetry (measuring the altitude of an object above a fixed level) to study the Earth’s polar regions. It operated from 2003 to 2009. Its successor, ICESat-2, is scheduled for launch in 2016.
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- Airborne survey to study changes to Antarctica's sea ice, glaciers and ice sheets - Oct 09, 2009
- Satellite records Antarctica ice shelf's retreat - Apr 08, 2012
- Pine Island Glacier behind thinning ice in Antarctica - Jun 21, 2010
- Warming ocean layers melt polar ice sheets faster - Jul 04, 2011
- Alarm bells over Greenland ice melt - Oct 26, 2011
- Ice shelves attached to Antarctica are disappearing - Feb 23, 2010
- Chunk of Greenland glacier breaks up overnight - Jul 13, 2010
- Melting icebergs causing sea level rise - Apr 29, 2010
- Ice Shelves on Antarctic Peninsula in danger - Feb 23, 2010
- Antarctic ice shelf faces threat from warm waters - May 10, 2012
- Vanishing ice shelves in Antarctic Peninsula could result in sea-level rise - Feb 23, 2010
- Global warming curbs won't prevent steep sea rise - Mar 21, 2012
Tags: british antarctic survey, cambridge uk, eart, earth processes, floating ice, glaciers, icesat, land elevation satellite, laser altimetry, laser instrument, melting ice, nasa, nasa headquarters, sea level rise, study period, surface height measurements, tom wagner, understanding earth, warm ocean currents, west antarctica