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Satellite image of the Larsen Ice Shelf extending along the east coast of the Antarctic Peninsula. Photo: DLR/TerraSAR-X
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El Niño and La Niña: Contrasts in West Antarctic Snowfall
Helmholtz researchers from the GFZ German Research Centre for Geosciences have found out how the ice mass covering Antarctica has changed over time. They evaluated data from the gravity field satellite mission GRACE and looked at the two regions, which apparently are particularly susceptible to climate change: Large ice shelves on the Antarctic Peninsula are disintegrating and in the Amundsen Sea Embayment in West Antarctica glaciers and ice sheets draining into the Amundsen Sea are quickly retreating inland. "The GRACE time series enabled for the first time direct observation of how the ice mass in the two areas varies from year to year due to precipitation fluctuation", explains Dr Ingo Sasgen. This variation apparently is connected with the global climate phenomenon El Niño. "The altered atmospheric circulation during El Niño warm phases results in less precipitation and hence to a decline in ice mass on the Antarctic Peninsula, whereas in the Amundsen Sea Embayment snowfall is increased", illustrates GFZ researcher Professor Dr Maik Thomas. Conversely, this situation is completely reversed in La Niña years, with more snowfall on the Antarctic Peninsula and less in West Antarctica. This converse variation is superposed by a continuous disintegration of ice mass in both areas, which is accordant with the global climate change; this was also revealed by the GRACE data since 2002: Each year, West Antarctica loses 110 gigatonnes ice. Thus, both areas together are responsible for about a tenth of the currently observed global mean sea level rising by 3 millimetres per year.
