Antarctica's once-massive Larsen B Ice Shelf is melting rapidly, and will likely be entirely gone by the end of this decade, according to a new report from NASA. A team led by Ala Khazendar of NASA's Jet Propulsion Laboratory (JPL) found the shelf is developing large cracks while its tributary glaciers rapidly disintegrate.
"Change has been relentless."
"Although it’s fascinating scientifically to have a front-row seat to watch the ice shelf becoming unstable and breaking up, it’s bad news for our planet," Khazendar said in a statement. "This ice shelf has existed for at least 10,000 years, and soon it will be gone."
Ice shelves prevent glaciers from floating from Antarctica toward the ocean and contributing to a rise in sea level. Scientists have long acknowledged the effect of climate change on the world's ice sheets, but several recent studies suggest things are worse than initially thought. A 2013 study debunked the idea that isolated ice sheets in East Antarctica were immune to the effects of global warming. A study published last month found the rate at which Antarctica's ice sheets are melting has accelerated greatly over the last two decades. Khazendar says the Larsen B timeline is based on a widening rift near the ice shelf's grounding line, which will eventually crack all the way across.
Scientists believe the Larsen B Ice Shelf has existed since the end of the last major glaciation 12,000 years ago, according to the National Snow and Ice Data Center (NSIDC). It was about 220 meters (720 feet) thick. The shelf, a floating ice mass on the eastern side of the Antarctic Peninsula, partially collapsed in 2002 when a large chunk on its northern side broke off and shattered. During that collapse, a total of about 3,250 square kilometers of shelf area melted within 35 days, according to the NSIDC.
The shelf has three main tributary glaciers (two of which are apparently named after Moby Dick characters), which researchers originally assumed to be stable. Now the JPL has found that two of those glaciers have thinned by 65 to 72 feet since 2002, and their flow speed has accelerated as much as eightfold, according to NASA.
"What is really surprising about Larsen B is how quickly the changes are taking place," Khazendar said. "Change has been relentless."