World's largest ice sheet is stable, researchers say
Last Updated: Wednesday, June 27, 2007 | 8:43 AM ET
The Associated Press
An ice sheet in Antarctica that is the world's largest — with enough water to raise global sea levels by 61 metres — is relatively stable and poses no immediate threat, according to new research.
While studies of the Greenland and West Antarctic ice sheets show they are both at risk from global warming, the East Antarctic ice sheet will "need quite a bit of warming" to be affected, Andrew Mackintosh, a senior lecturer at Victoria University, said Wednesday.
The air over the East Antarctic ice sheet, an ice mass more than 3,000 kilometres across and up to four kilometres thick centred on the South Pole, will remain cold enough to prevent significant melting in the near future, the New Zealand-led research shows.
But it eventually may become vulnerable to the effects of rising sea levels driven by the melting of other ice sheets, Mackintosh's team found. Their research was published this week in the journal Geology.
'Our research suggests changes in sea levels due to global warming will not be caused by changes in the East Antarctic Ice Sheet yet.'—Andrew Mackintosh, Victoria University
"The East Antarctic ice sheet is the largest and the coldest, and is going to be the last to respond in any great way" to global warming, he said. "Our research suggests changes in sea levels due to global warming will not be caused by changes in the East Antarctic Ice Sheet yet."
The researchers found that starting 13,000 years ago and ending roughly 7,000 years ago, when sea levels rose by more than 100 metres, the East Antarctic ice sheet thinned by 200 to 350 metres. Rising waters during that period would have lifted the buoyant ice sheet's edges off its rocky base, causing pieces to detach or "calve" and melt.
If the sheet experienced such calving again, even small changes could have a significant impact, the researchers said.
The study — conducted with Australia's Macquarie University, and the Australian Nuclear Science & Technology Organization — did not predict how much sea levels would have to rise before the sheet's edges started to break away.
Glaciologist Wendy Lawson, head of geography at Canterbury University, was not involved in the study, but said the new research supported previous modelling indicating the sheet was stable.
"There is no short-term risk as far as the overall magnitude of the East Antarctic ice sheet goes," she said.
