Jess Tyler jtyler at scibizmedia.com.au
Fri Dec 14 03:55:59 CET 2007

14 December 2007

  ice sheets a hot topic

One of the hottest issues in global sea level rise is uncertainty  
around the potential contribution of melting Antarctic and Greenland  
ice, say leading Australian climate scientists.

The comments come on International Polar Year’s Ice Sheet Day, and  
follow the release of the World Meteorological Organisation’s 2007  
global climate data report this morning, which includes reference to  
'...significant climate change in the Arctic. The record-low Arctic  
sea ice and the never before seen opening of the Canadian Northwest  
Passage are some of the ‘remarkable climatic events recorded so far  
in 2007.’

Professor Bruce Mapstone, CEO of the Antarctic Climate & Ecosystems  
Cooperative Research Centre (Antarctic & Climate CRC) said that while  
ice sheets are a key element in sea level projection, there is a  
large uncertainty about how much the Antarctic and Greenland ice  
sheets will contribute to future sea level rise in a warming world.

Earlier this year, the Intergovernmental Panel on Climate Change  
Assessment Report AR4 carried an important rider on that very issue,  
saying that:
	“Because understanding of some important effects driving sea level  
rise is too limited, [the] report does not assess the likelihood, nor  
provide a best estimate or an upper bound for sea level rise. Model- 
based projections of global average sea level rise for 2090-2099…do  
not include uncertainties in climate-carbon cycle feedbacks nor the  
full effects of changes in ice sheet flow, therefore the upper values  
of the ranges are not to be considered upper bounds for sea level  
rise. They include a contribution from increased Greenland and  
Antarctic ice flow at the rates observed for 1993-2003, but this  
could increase or decrease in the future.”

“The contribution of the great ice sheets is one of the largest  
unknowns in predictions of global sea level rise, so knowing more  
about the ice system is of utmost importance and it is one of the  
biggest challenges facing climate science.” says Professor Mapstone.

“Observations show that current sea level rise is tracking on the  
upper boundary of projections, and that there are major changes to  
polar climate, particularly in the Arctic but also around the  
Antarctic Peninsula.  Arctic sea ice is decreasing significantly but  
there are yet no clear trends in the extent of Antarctic sea ice.

The Antarctic Climate and Ecosystems CRC is undertaking research into  
the present and possible future sea level change from thermal  
expansion of the ocean and from melt of the Antarctic Ice Sheet.  The  
CRC also studies sea ice and other aspects of the Antarctic climate  

For information contact:
Jess Tyler, Media Officer
Antarctic Climate & Ecosystems Cooperative Research Centre
Tel: +61 3 6226 2265
Mob: 0408 298 292
Email: media at acecrc.org.au

About the Antarctic Climate & Ecosystems Cooperative Research Centre
The Antarctic Climate & Ecosystems Cooperative Research Centre  
(Antarctic & Climate CRC) is a collaborative partnership dedicated to  
the study of atmospheric and oceanic processes of the Southern Ocean,  
their role in global and regional climate change, and their impact on  
sustainable management of Antarctic marine ecosystems.

The ACE CRC’s core partners are the Australian Antarctic Division,  
the Australian Bureau of Meteorology, CSIRO Marine and Atmospheric  
Research, and the University of Tasmania. Supporting partners are the  
Alfred Wegener Institute for Polar and Marine Research (Germany), the  
Australian Greenhouse Office, the Australian National University, the  
National Institute of Water and Atmospheric Research (New Zealand),  
Silicon Graphics International, and the Tasmanian Department of  
Economic Development.

Established and supported under the Australian Government’s  
Cooperative Research Centre Programme

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