10 year ice shelf project nears completion
30 October 2009Australian researchers heading to Antarctica today will return to the Amery Ice Shelf to complete a decade-long project on the effects of climate change.
The project, known as AMISOR (Amery Ice Shelf Ocean Research), is providing information on the climate history of the region and its probable response to global warming.
Leader of the Australian Antarctic Division's Ice, Ocean, Atmosphere and Climate program, Dr Ian Allison, said that scientists would be measuring and sampling through the Amery Ice Shelf at several test sites through an ice thickness of around 650 m.
"AMISOR has been directly measuring ocean characteristics, seawater circulation and the melt-freeze processes occurring at the base of the shelf using bore holes through the ice into the underlying ocean cavity," Dr Allison said.
The program is also sampling sea-floor sediments up to 1000 m below the top of the shelf
"Bore holes are created using a purpose-built hot water drill system to melt its way right through the 650 m ice shelf.
"Sampling is done while the bore hole is kept open, and includes the collection of short ice cores, sea floor sediment records, and the measurement of profiles of seawater properties.
Floating ice shelves provide a buffer between the continental ice and the ocean. They are in direct contact with the ocean and vulnerable to changing ocean circulation and temperature. Once an ice shelf is removed, it is believed that that continental ice streams and glaciers are able to discharge grounded ice more rapidly into the ocean and leading to increased sea level rise.
The Amery Ice Shelf is the largest ice shelf in East Antarctica with an area of around 60,000 square kilometres – nearly as large as Tasmania.
It drains the Lambert Glacier-Amery Ice Shelf system which accounts for 16 per cent of the area of the grounded East Antarctic ice sheet.
Dr Allison said that recent forays to the region had found that parts of the ice shelf base are permeable, and also discovered complex sea-floor communities unlike anything previously reported so far beneath an ice shelf.
"These new observations provide a better context for interpretation of the history of the ice shelf and for estimating future changes and their consequences."
Antarctic ice shelves are important components of the climate system and this project combines a multi-disciplinary approach to give a comprehensive picture on which to base future estimates of climate.