Double paradox in Antarctica

Antarctica in the morning after a snow shower.

RISING temperatures due to global warming might result in more snowfall in Antarctica. A recent quantification through climate model simulations by an international team of scientists from Germany, the Netherlands and the United States, led by the Potsdam Institute for Climate Impact Research in Potsdam, Germany, shows that each degree of regional warming could increase snowfall on the ice continent by about 5 per cent. But their research also shows that stronger snowfall will increase future ice discharge from Antarctica.

The work has been published in a recent issue of the journal “Nature Climate Change”. Their research builds on high-quality ice-core data and fundamental laws of physics captured in global and regional climate model simulations. The results provide a missing link for future projections of sea-level rise because of the contribution by Antarctic snowmelt.

Global warming leads to more precipitation as warmer air holds more moisture and in cold Antarctica this takes the form of snowfall. Hence, earlier research suggested that the Antarctic ice sheet might grow under climate change. The research, however, also shows that the increase in snowfall will not save Antarctica from losing ice since a lot of the added ice will be transported out into the ocean by its own weight. That is, warming brings more snowfall, more snowfall enhances ice loss. Ice-cores drilled in different parts of Antarctica provide data that can help us understand the future.

“Snow piling up on the ice is heavy and presses down—the higher the ice, the more the pressure. Because additional snowfall elevates the grounded ice sheet on the Antarctic continent but less so the floating ice shelves at its shore, the ice flows more rapidly into the ocean and contributes to sea level,” co-author Ricarda Winkelmann explains. Accounting for this effect, a 5 per cent increase in snowfall on Antarctica would mean a calculative drop in sea level by about three centimetres after 100 years. Other processes, however, will effect a net rise in sea level in the end.