The United States’ National Climate Assessment estimates we’ll see 1-4 feet of sea level rise by 2100, citing the complicated dynamics of Greenland’s and Antarctica’s ice sheets as “the primary reason that projections of global sea level rise includes such a wide range of plausible future conditions.” The questions swirling around the future of the West Antarctic ice sheet add to the considerable uncertainty policymakers and planners face when trying to prepare for sea level rise. If every country met its Paris Agreement commitments, the world would warm to 2.7 degrees Celsius. In a future where carbon emissions continue unabated, warming air temperatures would force its collapse within 250 years.ĭeConto said they are still working to identify the exact tipping point that would trigger this dramatic fracturing of the West Antarctic ice sheet, but work he presented at the American Geophysical Union meeting this past winter suggests it’s somewhere between 2-3 degrees Celsius of warming. Their 2016 research, which predicts how marine ice cliffs will react to atmospheric warming under a variety of future greenhouse gas scenarios, found that in a future where we quickly and radically cut greenhouse gas emissions, the West Antarctic ice sheet would be relatively stable for centuries. New, not-yet-published research from the same pair revises the estimate for the end of the century downward substantially, but the longer-term picture is still bleak, with a rate of sea level rise that could “be very challenging for coastal planners and engineers to cope with,” DeConto wrote in an email, “likely leading to large-scale retreat from the coast in some places and loss of some low lying islands.” In a paper that outlined this marine ice cliff instability theory in 2016, authors Rob DeConto from the University of Massachusetts, Amherst, and David Pollard from Penn State University raised alarm by predicting that Antarctica by itself could contribute up to 3 feet of sea level rise by 2100. And ice cliff modeling suggests that if that process starts, there might not be anything to stop it. If Thwaites retreats far enough inland and reaches a certain thickness, physics dictates it will start collapsing under its own weight. The seafloor underneath the glacier slopes downward as it goes inland in what scientists call a “retrograde slope,” and the ice sitting on top of it gets thicker and thicker. If the entire floating ice shelf at Thwaites fractures into icebergs, what’s left at the edge of the glacier is a giant cliff of ice whose shape makes it particularly vulnerable to runaway collapse. “Whether it leads directly to further changes or not, we just have to wait and see,” Larter said. “You'd expect it might lead to even further acceleration of flow of the glacier,” Larter said of the blowout.ĭuring the next summer thaw, scientists will watch to see if more of the ice shelf inland from the mélange starts to crumble. Instead, much of the ice there is actually what scientists call a “mélange,” a slushy mix of icebergs and other floating bits of ice formed by fracturing at an ice front. ![]() This big blowout confirmed that there's very little actual ice shelf left in the western part of Thwaites Glacier. Thwaites’ ice shelf stabilizes the whole glacier, acting like a cork in a wine bottle to slow the seaward flow of ice from the continent’s interior. Coupled with the thinning of the glacier and its faster flow, “this is one expression of the fact that Thwaites Glacier is putting more and more ice into the ocean.” “It's another step in the retreat,” Larter said. But it is a sign of the glacier’s instability. The massive blowout of icebergs won’t itself change sea levels, as the ice that fractured off deep into the ice shelf had already been floating. This winter’s expedition aboard the Palmer marked the first field season of a five-year, international research collaboration to discover just how much, and how fast, Thwaites Glacier might add to rising seas. Part 6: For this marine tech, Antarctica’s Thwaites Glacier drives home threat of climate change.Part 5: These scientists used small explosions to 'see' under Antarctica and measure how fast a key glacier will melt.Part 4: These high-tech seals are charting future sea level rise | How can a seal track climate change?. ![]() Part 3: On a journey to Antarctica, a New Orleans chef awakens to the threat of melting ice.Part 2: This submarine’s historic tour under Thwaites Glacier will help scientists predict sea level rise.Part 1: Is Thwaites Glacier doomed? Scientists race against time to find out.This is the last in a series, Into the Thaw: Decoding Thwaites Glacier.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |