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Underestimating rising sea levels?

RECENTLY persistently higher temperatures caused by global warming have led glaciers and the polar ice caps to greater-than-average melting. The massive ice sheets that cover Greenland and Antarctica are also melting at an accelerated pace.

The ice caps – Greenland and Antarctic – contain huge amounts of fresh water – around 70% of all the freshwater on Earth. Estimates suggest that if the Greenland ice sheet was to melt away to nothing, sea levels would rise around six meters. If the West Antarctic Ice Sheet (WAIS) were to melt, this would add around six meters to sea levels. If the East Antarctic Ice Sheet (EAIS) were to melt as well, seas would rise by around 70 meters. In a process that is accelerating, all three ice caps are losing mass. A 1% loss of ice from these three sources would produce a likely increase in sea levels of around 76cm. With the thermal expansion implied by such melting, and contributions from melting glaciers, the oceans would actually rise far more.

The study, published in the journal Nature, says that Antarctica’s ice cap is less stable than previously thought and sea levels could rise more rapidly than predicted. Previous studies had predicted sea level rises of up to a meter this century, however, these projections failed to anticipate any significant contribution from Antarctic ice. Only passive melting of the Antarctic by warmer air and seawater are taken into account. However this new study considers the possibility of more active processes, such as disintegration of ice cliffs.

This increase would double the previously expected sea level rise to a two-meter rise by the end of the century.

However, the study says that a global commitment to the most ambitious goals set out in the 2015 Paris agreement would halt this melting, leaving the Antarctic ice sheet largely intact. (Floro Mercene)