Greenland ice sheet lost a record 530 billion metric tons of ice last year, study says
The melting Greenland ice sheet is already one of the largest contributors to sea level rise. But now, scientists have confirmed that the region saw a record amount of ice melt last year — shattering previous records with 532 billion metric tons of ice lost.
The amount of ice lost in 2019 was more than twice the annual average since 2003, when NASA satellites began precisely recording how much ice is melting, according to a recent study in the journal Communications Earth & Environment. Nearly half was lost in July alone, during a historic heat wave that swept across Europe.
Researchers compared data from satellites with regional climate models to make their calculations. The two satellite missions, GRACE and GRACE-FO, which monitor the Earth's gravitational field, play key roles in the observations of the ice sheet.
Greenland's ice melt is a major concern among scientists — if it were to entirely melt, it would raise global sea levels by at least 20 feet. The previous record for ice melt for a single year was 464 billion metric tons in 2012.
"Not only is the Greenland ice sheet melting, but it's melting at a faster and faster pace," study lead author Ingo Sasgen, a geoscientist at the Alfred Wegener Institute in Germany, told The Associated Press.
Last year's melt in Greenland added .06 inches to global sea level rise. Study co-author Alex Gardner, a NASA ice scientist, called that amount "huge" and "astounding."
Melting ice sheets and glaciers all over the world, in addition to oceans expanding as they warm, are leading to rising sea levels, coastal flooding and extreme weather events globally.
Scientists say 2017 and 2018 saw unusually low ice melt due to colder summers and a high amount of snowfall, but 2019 data reveals a return to extremely high melt rates.
The new satellite data accounts for snowfall, allowing a more precise net loss calculation. Snowfall in 2019 was below average, contributing to the record figure.
Researchers said a number of factors have contributed to an increase in surface melting, including, perhaps most prominently, a phenomenon they call "blocking," which keeps warm air over the region for longer periods of time.
"After a two-year 'breather', in 2019 the mass loss increased steeply and exceeded all annual losses since 1948, and probably for more than 100 years," Sasgen said in a news release. "There are increasingly frequent, stable high-pressure areas over the ice sheet, which promote the influx of warm air from the middle latitudes. We saw a similar pattern in the previous record year 2012."
The Arctic is warming at three times the rate of the global average. Just 15 years from now, the Arctic Ocean may be functionally ice-free for part of the year as sea ice vanishes, a new study found.
That's one of the most aggressive timelines for this threshold to be reached and, if correct, is one of the more direct signs that humans are warming the Earth's climate at an even more dramatic pace than expected.
"We see substantial variations from year to year," Sasgen said. "But the five years with the highest losses since 1948 were all in the last decade."
