WELLINGTON, Sept. 20 (Xinhua) -- Small changes in temperature in the Southern Ocean can affect the interior of the Antarctic ice sheet and contribute to global sea level rise, according to a New Zealand-led study.
Scientists at Victoria University used supercomputer facilities to generate a new continental-scale ice sheet model, using a much higher resolution than previously possible, to demonstrate how the whole ice sheet was sensitive to temperature changes on its margins.
The study showed that temperature changes penetrated the ice sheet through narrow corridors of fast moving ice, known as ice streams, said a statement from the university Thursday.
"We found that the ice streams, which are like arteries of flowing ice, are capable of triggering rapid, significant changes right through to the interior of the ice sheet," Dr Nicholas Golledge a senior research fellow at the university's Antarctic Research Centre, said in the statement.
The researchers ran model simulations and compared the results with geological reconstruction of the ice sheet as it would have been 20,000 years ago, during the last glacial high point, enabling them to analyze the effects of ocean warming and sea- level rise across the entire Antarctic ice sheet.
The results showed that while glacier accelerations triggered by changes in the Southern Ocean were relatively localized, the extent of the ice-sheet thinning was far more widespread.
Certain areas of Antarctica proved to be more susceptible than others to changes in ocean temperatures, and the fast-flowing glaciers in the Weddell Sea, the Amundsen Sea, the central Ross Sea and the Amery Trough responded most quickly.
The finding was important because melting of the polar ice sheets had been one of the key uncertainties in predicting future sea-level rise, and the results implied a rapid response from the ice sheet as the ocean around Antarctica warmed, said Golledge.
Eighty percent of the heat from global warming had been taken up by the ocean and much of the warming was in the Southern Ocean around Antarctica, where warm ocean currents were already melting the marine margin of the ice sheet in the Amundsen Sea, said Golledge.
"The ice sheets lock up vast quantities of water, which has the potential to raise global sea levels by meters, but how fast this will happen remains an open question.
"Reducing the uncertainty about future sea-level rise due to Antarctic ice sheet loss is critical, and our research is helping to achieve this."
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