Changes in Earth’s climate due to human activity have been a pressing issue for policy makers and community leaders around the world for years, and recent studies show that the impacts of those changes are already taking hold in oceanic and atmospheric systems. Scientists predict that one symptom of a changing climate will be a deepening of the Amundsen Sea Low, a climatological low-pressure center that plays a big role in the regional climate. Here Thomas et al. provide new evidence that this change—and, ultimately, the melting of West Antarctic ice sheets—is already under way.
The team found evidence for the change in two ice cores drilled in Ellsworth Land, West Antarctica. A 136-meter core was drilled between the Ferrigno and Pine Island glaciers, and a 140-meter core was drilled on the western Bryan Coast. Together, the cores provide a physical record of roughly 300 years of snowfall, which is calculated as the net result of precipitation, sublimation, snow drift, and melt.
The researchers found that average annual snowfall at Ferrigno and Bryan Coast was relatively constant before 1900. After 1900, snowfall rates began to increase. Between 2000 and 2009, snowfall jumped by 27% at Ferrigno and by 31% at Bryan Coast compared to baseline values calculated from 1712 to 1899. The researchers found that these results correlated with ice core records elsewhere on the continent.
The authors also tied the results to the behavior of the Amundsen Sea Low, which is strongly influenced by even bigger climate actors like the Southern Annular Mode and the El Niño–Southern Oscillation. These phenomena influence regional sea surface temperature, atmospheric circulation, and sea level pressure. Changes in sea level pressure generate changes in snowfall and drive meridional winds that bring moist air up onto the Ellsworth coast, causing ocean upwelling and melting of the West Antarctic ice shelves.
The researchers contend that the dramatic increase in snowfall is a reflection of climate change driven by human activity, deepening the Amundsen Sea Low and driving the melting of the Antarctic ice sheets as early as the 1920s. Since thinning glaciers along the Amundsen coast are one of the biggest Antarctic contributions to sea level rise, these results have global consequences. (Geophysical Research Letters, doi:10.1002/2015GL065750, 2015)
—Lily Strelich, Freelance Writer
Citation: Strelich, L. (2016), Climate change drives increasing snowfall in western Antarctica, Eos, 97, doi:10.1029/2016EO044021. Published on 21 January 2016.