The Cryosphere, September 8
Ice loss from the Antarctic Peninsula has accelerated over the past four decades. Two main factors, meltwater and wind circulation, appear to be destabilizing glaciers in this region, in addition to rapid warming (for much of this period, the Peninsula was the fastest-warming place on Earth). First, water from melting snow sinks below the top layers of glaciers during the summer, warming up the entire snowpack and reducing the ability of that water to refreeze. Second, the SAM (Southern Annular Mode) westerly winds that circle Antarctica dictate the amount of snow that accumulates on the surface. When these winds are closer to the main Antarctic continent, they create a low-pressure system that decreases rain and snowfall on the east side of the Antarctic Peninsula. Since the 1980s, these winds have indeed been moving closer and closer to the continent, decreasing annual snowfall and formation of new ice. This may speed destabilization and collapse of the Larsen C Ice Shelf, causing glaciers on the Peninsula to lose ice more rapidly. While the Antarctic Peninsula holds relatively little land ice and sea-level rise compared to the main Antarctic continent, this process of ice shelf collapse, and subsequent rapid land ice loss may be a harbinger of similar processes to come, especially from West Antarctica.