Melting of Antarctica’s ice sheet responsible for 20 to 25 percent of global sea level rise – Says study

The melting of Antarctica’s ice sheet is currently responsible for 20 to 25 percent of global sea level rise, according to the study, titled “Slowdown in Antarctic Mass Loss from Solid Earth and Sea-Level Feedback.”

Antarctica’s ice sheet melting faster. Photo credit: Hurriyet Daily News

The study, published on Thursday in Science, notes that “there are two primary causes of global mean sea level rise – added water from melting ice sheets and glaciers, and the expansion of sea water as it warms.”

Scientists at NASA’s Jet Propulsion Laboratory in Pasadena, California, have gotten one step closer to understanding what Antarctica’s ice sheet – and the sea level rise that occurs as it melts – will look like centuries from now.

The scientists found that projections for the next 100 years are within 1 percent of previous projections for that time period; however, further into the future, they observed some significant differences.

“We found that around the year 2250, some of these solid Earth processes started to offset the melting of the ice sheet and the consequent sea level rise,” Larour said. In other words, they actually slowed the melting down.

The team noted that a hundred years even further into the future – by 2350 – this slowdown means that the melting of the ice sheet is likely to contribute 29 percent less to global sea level rise than previous models indicated.

“One of the main things we learned was that as grounded ice retreats inland, the bedrock under it lifts up elastically,” said Erik Ivins, a co-author of the study. “It’s similar to how a sofa cushion decompresses when you remove your weight from it. This process slows down the retreat of the ice sheet and ultimately the amount of melting.”

Although this sounds like good news, the scientists say it’s important to keep it in perspective. “It’s like a truck traveling downhill that encounters speed bumps in the road,” said JPL’s Eric Larour, first author of the study. “The truck will slow down a bit but will ultimately continue down the hill” – just as the ice sheet will continue to melt and sea level will continue to rise.

The breakthrough of this study, he added, was to “reach resolutions high enough to capture as many of these ‘speed bumps’ as possible and determine their effects in Antarctica while also modeling sea level rise over the entire planet.”