New Brunswick, N.J. (Nov. 9, 2018) – Rutgers researcher Åsa K. Rennermalm, an Arctic hydroclimatology expert, has studied the melting Greenland ice sheet for 20 years and spent last spring collecting ice cores in the Kangerlussauq section.
“I was taught that the Arctic could be considered the canary in the coal mine for climate change, because change would be observed here first,” said Rennermalm, an associate professor in the Department of Geography in the School of Arts and Sciences at Rutgers University–New Brunswick. “Based on the scientific studies that others and I have done in the Arctic, I am here to tell you that the bird is dead. The Arctic is changing at an alarming rate and the rest of the world is next. The meltwater in Greenland that is escaping to the ocean will cause havoc and despair as it will raise the sea level in heavily populated coastal regions all around the world.”
Rennermalm and her team study Greenland ice sheet melting and how freshwater escapes the ice sheet and winds up in surrounding oceans, where it has a huge influence on global sea levels, marine ecosystems and ocean circulation. The team’s research, which is funded by the National Science Foundation and NASA, focuses on the infiltration of glacial meltwater, firn (an intermediate stage between snow and ice) and layers of ice called ice lenses. She also studies stream flow on and off the ice sheet.
“We are following the water from its creation on the surface of the ice sheet,” Rennermalm said. “At high ice sheet elevations, most meltwater infiltrates into snow and refreezes, which we study by analyzing 20-meter deep cores retrieved during month-long expeditions in spring 2017 and 2018.”
Instead of running off into the ocean, a substantial fraction of Greenland ice sheet meltwater is retained in firn (liquid or refrozen). Unusually thick, near-surface ice lenses were recently discovered in firn and are thought to be the result of exceptionally large recent melt events. This suggests that larger volumes of meltwater may have been prevented from percolating into deeper firn layers in recent years, compared with previous typical observations. Instead, such meltwater may have run off immediately into the Atlantic Ocean, according to Rennermalm.
As a result, a new firn “state” must be accounted for when attempting to quantify the mass of the ice sheet. Estimates are likely subject to larger uncertainty than previously thought. Refreezing, which creates ice lenses, is a crucial process in the redistribution of surface runoff and the determination of the Greenland ice sheet surface mass, Rennermalm says.
Rennermalm, a physical geographer who oversees the Arctic Hydroclimatology Research Laboratory, is available to comment at [email protected]
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