BBC Environmental Science – The collapse of a major polar ice sheet will not raise global sea levels as much as previous projections suggest, a team of scientists has calculated. Writing in Science, the researchers said that the demise of the West Antarctic Ice Sheet (WAIS) would result in a sea level rise of 3.3m (10 ft). Previous estimates had forecast a rise in the region of five to six metres.
However, they added, the rise would still pose a serious threat to major coastal cities, such as New York. “Sea level rise is considered to be the one of the most serious consequence of climate change,” lead author Jonathan Bamber told the Science podcast. “A sea level rise of just 1.5m would displace 17 million people in Bangladesh alone,” he added. “So it is of the utmost importance to understand the potential threats to coastlines and people living in coastal areas.”
Professor Bamber, from the University of Bristol’s Glaciology Centre, said that the WAIS posed “potentially one of the most serious threats”.
The world has three ice sheets, Greenland, East Antarctica and West Antarctica, but it is the latter that is considered most vulnerable to climatic shifts.
“It has been hypothesised for more than 30 years now that the WAIS is inherently unstable,” he explained. “This instability means that the ice sheet could potentially rapidly collapse or rapidly put a lot of ice into the oceans.”
When the idea first emerged in the late 1970s, it was estimated that global sea level would rise by five metres if the WAIS collapsed.
Current projections suggest that a complete collapse of WAIS would result in an increase of up to six metres. But Professor Bamber said that no-one had revisited the calculation, despite new data sets becoming available, and scientists developing a better understanding of the dynamics in the vast ice sheets. The original estimates were based on “very basic ice thickness data”, he explained.
“Ice thickness data gives you information about the depth of the bedrock underneath the ice sheet. Over the past 30 years, we have acquired much more ice thickness data over the whole of Antarctica, particularly over West Antarctica. We also have much better surface topography. Those two data sets are critical in determining two things.” (05/14/09)
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