clear the air


Antarctica: The Ticking Time Bomb

antarctica.jpgEven if a fraction melted, Antarctica could damage nations from Bangladesh to Tuvalu in the Pacific and cities from Shanghai to New York. It has enough ice to raise sea levels by 57 meters (187 ft) if it melted, over thousands of years.

A year after the U.N.’s Intergovernmental Panel on Climate Change (IPCC) projected sea level rises by 2100 of about 20 to 80 cms (8-32 inches), a Reuters poll of 10 of the world’s top climatologists showed none think that range is alarmist.

Six experts stuck by the projections, saying the response of ice sheets in Antarctica and Greenland was still unclear, and four other experts, including one of the authors of the IPCC report, projected gains could be 1 or even 2 meters by 2100.

Some island nations, such as the Maldives in the Indian Ocean, are building defenses costing millions of dollars and want to know how high to build. 

Antarctica may accumulate more ice this century because of warming, blamed by the IPCC mainly on human use of fossil fuels, rather than slide faster into the sea.The crux of this problem is that we are moving into an era where we are observing changes in the climate system that have never before been seen in human history.  Ice sheets fall into that category.

Quite simply, at this time we don’t have a good upper-range estimate of ‘how much sea- level rise and how fast’. Among worrying scenarios is the chance Antarctica will slide faster into the sea, perhaps if a ring of sea ice melts away in warmer oceans. Or melt water might flow under the ice sheets of Antarctica and Greenland, and act a lubricant to speed a slide.But glaciers can slow down as well as speed up.

Most of the projected sea-level rise by 2100 will be because water in the oceans expands as it warms, with little being added by the ice sheets.

Simon Turner  simon@marquetteturner.com.au

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