Sunday, June 1, 2014

Antarctic ice sheets unstable, massive sea level rise possible

Models of sea level rise tend to suggest gradual action, which will provide reasonable time for coastal communities to respond.

But a new study by University of Hawai`i researchers suggest that catastrophic sea level rise is possible. It has happened before.

(Image: Calypso corer onboard the research vessel Marian Dufresne II in the Scotia Sea. Credit: Michael Weber.)

Axel Timmermann, a professor with the International Pacific Research Center at UH is the co-author of a paper in Nature that looks at evidence of past cases of fast sea level rise. 

An international team of researchers studied deep sea sediment cores taken between the Falkland Islands and Antarctica.

They found evidence of multiple melting events, which they said suggest that warming conditions can lead to catastrophic melting of the immense Antarctica ice sheet. One such event took place 14,600 years ago. In that case, there was evidence that oceans rose 3 meters in a century. 

That works out to an inch and a half a year—many times the current rate of sea level rise and one that would very quickly overwhelm existing coastline development.

“An unusually strong flow of warm water towards Antarctica may have triggered these events. Our model experiments reveal further that the associated melting in turn increased the warm water flow, thus providing a positive feedback. This is a perfect recipe for rapid sea level rise,” Timmermann said.

“This is the first direct evidence that instabilities of the Antarctic ice sheet caused rapid sea level rise during the last glacial termination,” said Peter Clark, professor at Oregon State University.

The University of Hawai`i’s press release on the paper says it nmeans the Antarctic ice sheet is far less stable than previously understood.

Citation: Weber, M. E., Clark, P.U., Kuhn, G., Timmermann, A., Sprenk, D., Gladstone, R., Zhang, X., Lohmann, G., Menviel, L., Chikamoto, M. O., Friedrich, T. Ohlwein, C., 2014. Millennial-scale variability in Antarctic ice-sheet discharge during the last deglaciation, Nature,

© Jan TenBruggencate 2014

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