Greenland canyons ‘could contribute more to future sea level rise’

Deep and long canyons beneath Greenland’s glaciers could contribute more to future sea level rise, according to authors of a new research paper. Scientists at NASA and the University of California, Irvine (UCI), say canyons under Greenland’s ocean-feeding glaciers are deeper and longer than previously thought, increasing the amount of Greenland’s estimated contribution to future sea level rise. UCI Associate Project Scientist and lead author of the new research paper Mathieu Morlighem said, “The glaciers of Greenland are likely to retreat faster and farther inland than anticipated, and for much longer, according to this very different topography we have discovered. Ice loss from Greenland has accelerated during the last few decades. However, older ice sheet models predicted the speedup would be temporary because the glaciers would soon melt back onto higher ground and stabilize. The models projected that Greenland’s contribution to global sea level rise would therefore be limited. Morlighem’s new topography shows southern Greenland’s ragged, crumbling coastline is scored by more than 100 canyons beneath glaciers that empty into the ocean. Many canyons are well below sea level as far as 60 miles (100 kilometres) inland. Higher ground, where glaciers could stabilize, is much farther from the coastline than previously thought. The new finding questions the view that the recent accelerated ice loss will be short lived. Coauthor Eric Rignot of UCI and NASA’s Jet Propulsion Laboratory (JPL), Pasadena, California, said, “We have been able to make a quantum leap in our knowledge of bed topography beneath ice sheets in the last decade, thanks to the advent of missions like NASA’s Operation IceBridge in combination with satellite data on the speed these ice sheets are flowing.” The research papers illustrate clearly the globe’s ice sheets will contribute far more to sea level rise than current projections show, he said.