The retreat of Antarctic ice shelves is not new according to research published this week (24 Feb) in the journal Geology by scientists from Universities of Durham, Edinburgh and British Antarctic Survey (BAS).
A study of George VI Ice Shelf on the Antarctic Peninsula is the first to show that this currently 'healthy' ice shelf experienced an extensive retreat about 9500 years ago, more than anything seen in recent years. The retreat coincided with a shift in ocean currents that occurred after a long period of warmth.
Whilst rising air temperatures are believed to be the primary cause of recent dramatic disintegration of ice shelves like Larsen B, the new study suggests that the ocean may play a more significant role in destroying them than previously thought.
The University of Durham's, Dr Mike Bentley, one of the leaders of the project said, 'We know that rising air temperatures can break up ice shelves but there has been a suspicion for some time that the role of the ocean may have been underestimated. This is some of the first evidence that a shift in ocean currents can actually destroy ice shelves. In this case it's possible that a preceding warm period may have primed the ice shelf to disintegrate when the ocean currents shifted.'
The scientists analysed sediments from the bottom of a freshwater lake close to the edge of the present George VI Ice Shelf. The results revealed that about 9500 years ago the ice shelf retreated, allowing the sea to flood into the lake. The ice shelf didn't reform until 1500 years later, and has been present ever since.
The findings are particularly relevant for other studies on the West Antarctic Ice Sheet where scientists have found that a relatively warm current, Circumpolar Deep Water, is causing high melt rates on the underside of an ice shelf in Pine Island Bay*.
The gradual removal of this ice shelf may be causing the glaciers inland to flow faster, which could lead to enhanced drainage of part of the West Antarctic Ice Sheet, and a consequent rise in sea level.
Research published this week (24 Feb) in the journal Geology
British Antarctic Survey
University of Durham
University of Edinburgh
Subscribe To TerraDaily Express
Polar Expedition Returns To Zhongshan Station
Beijing (XNA) Feb 09, 2005
A Chinese polar expedition team has successfully completed its 63-day, 3,078-kilometer field exploration trip to the highest icecap peak in Antarctica and returned to its home base in the continent, the State Oceanic Administration (SOA) said here Tuesday.
|The content herein, unless otherwise known to be public domain, are Copyright 1995-2016 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement All images and articles appearing on Space Media Network have been edited or digitally altered in some way. Any requests to remove copyright material will be acted upon in a timely and appropriate manner. Any attempt to extort money from Space Media Network will be ignored and reported to Australian Law Enforcement Agencies as a potential case of financial fraud involving the use of a telephonic carriage device or postal service.|