Greenland ice sheet melting at faster rate than previously thought

The combination of rising temperatures in both the air and oceans is leading to an effect similar to stirring ice in a drink, melting it faster than normal.

Greenland, the world's second-largest ice sheet, is even more in danger from global warming than previously believed.

The combination of rising temperatures in both the air and oceans is leading to an effect similar to stirring ice in a drink, melting it faster than normal, researchers from the University of Edinburgh and California San Diego found.

The scientists probed the world's largest island between 1979 and 2018, observing throughout the decades that rising air temperatures are amplifying the effects of melting caused by ocean warming.

Just this month, the EU's Copernicus Climate Change Service separately released ominous data from Greenland recorded last month. 

Copernicus said Greenland had exceptional temperatures that reached more than 8C above the monthly average in places, the warmest temperatures for September on record.

The Edinburgh and San Diego scientists said that the combination of air and ocean temperatures in tandem was akin to "the effect of how ice cubes melt more quickly if they are in a drink that is being stirred — the combination of warmer liquid and movement accelerates their demise".

Air temperature

Air temperature has had almost as much impact as ocean temperature on submarine melting in Greenland, with some regional variations, the scientists found.

Dr Donald Slater, of the University of Edinburgh’s School of GeoSciences, who led the study, said: “The effect we investigated is a bit like ice cubes melting in a drink — ice cubes will obviously melt faster in a warm drink than in a cold drink, hence the edges of the Greenland ice sheet melt faster if the ocean is warmer. 

"But ice cubes in a drink will also melt faster if you stir the drink, and rising air temperatures in Greenland effectively result in a stirring of the ocean close to the ice sheet, causing faster melting of the ice sheet by the ocean.

“This, unfortunately, adds to the overwhelming body of evidence showing the sensitivity of the Greenland ice sheet to climate change, hence the need for urgent action to reduce greenhouse gas emissions.”

Copernicus said that September's temperature outliers in Greenland were the highest observed in more than 40 years.

Senior scientist with Copernicus, Freja Vamborg, said: “Globally, according to Copernicus data, it was still one of the warmest Septembers. Greenland was unusually warm, with most of the territory experiencing the warmest September in the record dating back to 1979.”

Meanwhile, Trinity College Dublin and University of New South Wales Sydney scientists have unveiled what they say is the first comprehensive classification of the world’s ecosystems across land, rivers and wetlands, and seas.

Published in the leading scientific publication Nature, the study will enable more coordinated and effective biodiversity conservation, they said.