Warm Ocean Responsible for Melting the Undersides of Antarctic Ice Shelves

Warm ocean waters are melting the underside of the Antarctic ice shelves, and this is responsible for most of the continent's ice loss, states a new study. This research will help scientists advance projections of how Antarctica will respond to the warming oceans and also contribute to the rise in sea levels.

Scientists from University of California-Irvine conducted a comprehensive survey of all the Antarctic ice shelves and noticed that the ice dissolving from underneath accounted for 55 percent of shelf loss, right from the year 2003-2008. This rate exceeded the previous count that was considered by scientists.

Till date, it was believed that iceberg calving, or breaking of large chunks of ice, was responsible for most of the continent's ice loss. But the new study emphasized that basal melting, or ice dissolving from underneath, is the main driving factor for ice loss. This new finding has implications to clearly understand the interaction between Antarctica and change in climate.

"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," lead author Eric Rignot, a UC Irvine professor who's also a researcher with NASA's Jet Propulsion Laboratory in Pasadena, said in a press statement.

For the study, scientists combined a regional snow accumulation model, a new map of Antarctica's bedrock along with its ice shelf thickness, in elevation and velocity data that was gathered by Operation IceBridge, an ongoing aerial survey of Greenland and the South Pole conducted by NASA. They then compared this data with a similar study related to ice calving.

On comparing the data, the scientists realized that ice melting from the underside was much larger when compared to ice calving.

The three giant shelves that make up two-thirds of Antarctica's ice shelves, namely Ross, Ronne and Filchner, accounted for just 15 percent of melting; whereas the small ice shelves floating on warm water led to half the total melt water in the same period.

As a result of ice melting from the bottom between 2003-2009, the Antarctic ice shelves lost 2,921 trillion pounds (1,325 trillion kilograms) of ice each year. And the formation of icebergs led to 2,400 trillion pounds (1,089 trillion kilograms) of ice shelf mass loss each year during the same period, according to reports by IB Times.

"Ice shelf melt can be compensated by ice flow from the continent," Rignot said. "But in a number of places around Antarctica, they are melting too fast, and as a consequence, glaciers and the entire continent are changing."

The study was published in the journal Science.