Antarctic ice shelves are diminishing from the bottom up due to warm ocean water, and not from huge chunks breaking off into the ocean, says a new University of California Irvine (UCI) study.
Warm ocean water accounted for 55 percent of ice shelf loss between the years of 2003 and 2008, a greater percentage than iceberg calving where ice shelves break off into the ocean and go on to form objects such as icebergs.
"We find that iceberg calving is not the dominant process of ice removal. In fact, ice shelves mostly melt from the bottom before they even form icebergs," said Eric Rignot, a UCI professor who also works at NASA's Jet Propulsion Laboratory in Pasadena and is the lead author of the study detailing the findings.
Ice shelves, which are the result of glaciers flowing into the ocean and freezing over, are an important part of the Antarctic ecosystem. The way they melt affects the topography of Antarctica, which is incredibly susceptible to rising temperatures, and the buzzing global warming debate.
"This has profound implications for our understanding of interactions between Antarctica and climate change. It basically puts the Southern Ocean up front as the most significant control on the evolution of the polar ice sheet," Rignot said.
"Ice shelf melt can be compensated by ice flow from the continent," he added. "But in a number of places around Antarctica, they are melting too fast, and as a consequence, glaciers and the entire continent are changing."
Surprisingly, the large ice shelves of Ross, Filchner and Ronne, which make up two-thirds of Antarctica's ice shelves together, contributed very little to ice loss. Instead, it was a number of smaller ice shelves located around warm ocean water that accounted for over half the ice loss recorded.
You can read the full published study in the journal Science.
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