| Summary: | It was a warning shot picked up by seismometers around the world. Last September, a melting glacier collapsed, sending the mountaintop it propped up careening into the Dickson Fjord in East Greenland. The impact created a 650-foot tall tsunami - twice as tall as the Statue of Liberty - which crashed back and forth between the steep, narrow walls of the channel, booming so loud that the vibrations wrapped the globe in a 90-second interval pulse for 9-straight days. “It’s like a climate change alarm,” said Stephen Hicks, a seismologist at University College London. Hicks is part of an international team of researchers who finally sleuthed out the source of the vibrations that had been a source of bafflement ever since earthquake monitoring stations recorded the signal. Unraveling the mystery and mapping out the tsunami took the team of 68 scientists, from a wide range of disciplines, a full year. The resulting paper, recently published in Science, blames man-made global warming for the collapse. A century of greenhouse gasses heating up the atmosphere have eroded swaths of the Greenland ice sheet - frozen freshwater that holds back 23 feet of potential sea level rise. Hicks said this kind of landslide-tsunami has never been seen in East Greenland, an area that tends to experience less melt than the country’s Western perimeter. It could be a one-off, random event, or a sign of spreading instability. “We can maybe expect more of these events in the future,” Hicks said. Another group of researchers, from the University of Barcelona, recently confirmed the ice sheet’s trajectory. Their study, published in the Journal of Climate by the American Meteorological Society, found that days of extreme melt, linked to periods of hot, stagnant air in the summer, have doubled in frequency and also intensified since 1950. Roughly 40 percent of the ice Greenland loses in a year occurs during these extreme melting events. Grist thanks its sponsors. Become... |