Discovery of recent Antarctic ice sheet collapse raises fears of a new global flood

Discovery of recent Antarctic ice sheet collapse raises fears of a new global flood

SOURCE: Science DATE: December 18, 2018 SNIP: Some 125,000 years ago, during the last brief warm period between ice ages, Earth was awash. Temperatures during this time, called the Eemian, were barely higher than in today’s greenhouse-warmed world. Yet proxy records show sea levels were 6 to 9 meters higher than they are today, drowning huge swaths of what is now dry land. Scientists have now identified the source of all that water: a collapse of the West Antarctic Ice Sheet. Glaciologists worry about the present-day stability of this formidable ice mass. Its base lies below sea level, at risk of being undermined by warming ocean waters, and glaciers fringing it are retreating fast. The discovery, teased out of a sediment core and reported last week at a meeting of the American Geophysical Union in Washington, D.C., validates those concerns, providing evidence that the ice sheet disappeared in the recent geological past under climate conditions similar to today’s. If the finding holds up, the world may need to prepare for sea level to rise farther and faster than expected: Once the ancient ice sheet collapse got going, some records suggest, ocean waters rose as fast as some 2.5 meters per...
An Iceberg Five Times the Size of Manhattan Just Popped off West Antarctica

An Iceberg Five Times the Size of Manhattan Just Popped off West Antarctica

SOURCE: Earther DATE: October 30, 2018 SNIP: The Pine Island Glacier has been breaking off monstrous icebergs over the past five years, presenting a worrying sign that the West Antarctic is destabilizing. The latest occurred this weekend. Satellite imagery shows an iceberg roughly 115 square miles—five times the size of Manhattan—breaking off the front of the glacier. “What is mostly remarkable about this event is that the frequency of calving seems to increase,” Lhermitte said about the big boy ‘berg that broke off Pine Island Glacier. In the 2000s, so-called iceberg calving events of this magnitude used to occur roughly every five years. But since 2013, there have been four calving events including one last year. Icebergs break off the front of glaciers on the regular because glaciers are giant rivers of ice. As the upstream ice flows toward the sea, it puts tremendous stress on the ice below, causing icebergs to snap off. But what’s been happening at Pine Island Glacier in recent years could be a sign the flow is increasing. Satellite imagery put together by Lhermitte shows that the calving front has slowly receded for decades before beginning a sharp recession in recent years, including 3 miles of shrinkage since 2015 alone. All that activity has contributed to making Pine Island Glacier the most rapidly receding glacier on Earth. In addition to the calving area retreating, the ice has gotten thinner by about a meter annually over the past 15 years while shedding a staggering 45 billion tons annually. Much of that is driven by warm water eating away at it from underneath. If the disintegration...
Ice Apocalypse

Ice Apocalypse

SOURCE: Grist DATE: November 21, 2017 SNIP: The glaciers of Pine Island Bay are two of the largest and fastest-melting in Antarctica. (A Rolling Stone feature earlier this year dubbed Thwaites “The Doomsday Glacier.”) Together, they act as a plug holding back enough ice to pour 11 feet of sea-level rise into the world’s oceans — an amount that would submerge every coastal city on the planet. For that reason, finding out how fast these glaciers will collapse is one of the most important scientific questions in the world today. In the past few years, scientists have identified marine ice-cliff instability as a feedback loop that could kickstart the disintegration of the entire West Antarctic ice sheet this century — much more quickly than previously thought. A wholesale collapse of Pine Island and Thwaites would set off a catastrophe. Giant icebergs would stream away from Antarctica like a parade of frozen soldiers. All over the world, high tides would creep higher, slowly burying every shoreline on the planet, flooding coastal cities and creating hundreds of millions of climate refugees. All this could play out in a mere 20 to 50 years — much too quickly for humanity to adapt. “It could happen faster or slower, I don’t think we really know yet,” says Jeremy Bassis, a leading ice sheet scientist at the University of Michigan. “But it’s within the realm of possibility, and that’s kind of a scary thing.” There’s a recurring theme throughout these scientists’ findings in Antarctica: What we do now will determine how quickly Pine Island and Thwaites collapse. A fast transition away from fossil fuels...
A key Antarctic glacier just lost a huge piece of ice — the latest sign of its worrying retreat

A key Antarctic glacier just lost a huge piece of ice — the latest sign of its worrying retreat

SOURCE: The Washington Post, Yale e360 DATE: September 25, 2017 SNIP: An enormous Antarctic glacier has given up an iceberg over 100 square miles in size, the second time in two years it has lost such a large piece in a process that has scientists wondering whether its behavior is changing for the worse. The Pine Island Glacier is one of the largest in West Antarctica, a region that is currently Antarctica’s biggest ice loser. Pine Island, which loses an extraordinary 45 billion tons of ice to the ocean each year — equivalent to 1 millimeter of global sea level rise every eight years — is 25 miles wide where its floating front touches the sea, and rests on the seafloor in waters more than a half-mile deep. The single glacier alone contains 1.7 feet of potential global sea level rise and is thought to be in a process of unstable, ongoing retreat. The glacier is feared to be in a process of unstable, runaway retreat. The grounding line has been moving inland, and as it retreats, the seafloor bed dips downward, meaning that the ocean becomes even deeper and the ice becomes even thicker. Thus, further retreat should increase the rate of outward flow and lead to even more ice...