![]() ![]() That, in turn, threatens to drown low-lying areas from Florida to Bangladesh. As the world’s land-based glaciers melt with warming temperatures-particularly in Greenland and Antarctica-global sea level is rising. ( Learn more about the impacts of warming on the peninsula.) The global pictureĪlthough such big ice calving events can be purely natural phenomena, they have increasingly drawn attention from the scientific community and public because of their possible links to global climate change. And in July 2017, an expanse of ice the size of Delaware, some 2,240 square miles, broke off the Larsen C ice shelf on the Antarctic Peninsula. In 2015, the Pine Island Glacier-or PIG, as scientists affectionately call it-calved a 225-square-mile iceberg. Unauthorized use is prohibited.Īlthough it’s a large mass of ice, B-46 is hardly the largest in recent memory. Even more fissures can be seen cutting into the glacier itself.ī-46 will likely keep breaking up over the coming weeks, as it is buffeted by wind and currents in the Southern Ocean. In addition to the main ice canyons that mark the berg’s outer boundaries, it’s also bisected by many smaller crevasses, indicating that it’s already breaking up into smaller pieces. “It’s difficult to grasp the scale of what we are looking at,” Medley said from her workstation in the DC-8, behind a bank of monitors. In fact, the iceberg is so large and fresh, and still so close to the adjacent glacier, that it is hard to take in whole from an altitude of 1,500 feet-imagine flying over Manhattan just a few feet above the tip of the Empire State Building’s antenna. And when it calved, “it may have taken smaller bergs with it along the way,” Medley adds. The speed of the iceberg’s break has surprised scientists. Since 2009, the program has flown highly sensitive instruments over both poles in a variety of aircraft-including the vintage DC-8 used this week-to study how the ice-covered regions are changing as the planet warms. The B-46 iceberg is thought to have broken off just a few weeks later, on or around October 27, again according to satellite imagery, said Medley, who is also the deputy project scientist for NASA’s Operation IceBridge. Photograph by Thomas Prior, National Geographic The fissure that separates the B-46 iceberg from the shelf of the Pine Island Glacier in West Antarctica. “It’s possible it started before that, but it was in the polar winter then and we don’t have a record of it,” said Medley. In September, scientists studying satellite photographs had discovered a crack in the ice shelf. ( Read more about Antarctic melting and sea level rise.) As the glacier melts, largely due to warm seawater that’s being driven under its floating shelf by changing winds and currents, it contributes significantly to global sea level rise. Remote as it is, it’s one of the most famous and studied glaciers in the world-because it’s one of the fastest changing. Pine Island Glacier sits along the Amundsen Sea, west of the Antarctic Peninsula. “I’m 99 percent sure we are the first people to ever see this with our own eyes.” “This is a brand new feature,” said Brooke Medley, a glaciologist with NASA’s Goddard Space Flight Center in Maryland. ![]() ![]() The cliffs at its edges are 160 to 230 feet high. The new iceberg, named B-46 by scientists, is estimated to cover about 71 square miles, more than three times the size of Manhattan. “It’s incredible,” said another.Īnother giant chunk of ice had just broken off the glacier.Īs the jet continued its auto-controlled transect line, 1,500 feet over the ice, it crossed the main break-a huge white canyon that marked a detachment point of what was now an iceberg from the rest of the glacier’s floating ice shelf. There were broad smiles and exclamations. The sound of clicking shutters filled the noisy, drafty cabin of the DC-8. Huge, blocky fissures sliced across the giant white layer cake of the Pine Island Glacier, a fast-moving part of the West Antarctic ice sheet. Photographs by Thomas Prior, National Geographic ![]()
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