It melts Greenland ice sheet is already one of the biggest contributors to sea level rise. But now scientists have confirmed that the region saw a record amount of ice melt last year – breaking previous records with 532 billion metric tons of ice.
The amount of ice lost in 2019 was more than twice the annual average since 2003, when NASA satellites began recording exactly how much ice melted, according to a recent study in the journal Communications Earth & Environment. About half was lost in July alone, during a historic heat wave that swept through Europe.
Researchers compared satellite data with regional climate models to make their calculations. The two satellite missions, GRACE and GRACE-FO, which control the Earth’s gravitational field, play important roles in ice sheet observations.
Greenland’s ice melt is a major concern among scientists – if it were to melt completely, global sea levels would rise by at least 20 feet. The previous record for ice milk for a single year was 464 billion metric tons in 2012.
“Not only is the Greenland ice sheet melting, but it is melting at a faster and faster pace,” lead author Ingo Sasgen, a geoscientist at the Alfred Wegener Institute in Germany, told The Associated Press.
Last year, melting in Greenland added 0.06 inches to global sea level rise. Study co-author Alex Gardner, a NASA ice scientist, called that amount “enormous” and “amazing.”
Melting ice sheets and glaciers around the world, in addition to expanding oceans as they warm, lead to rising sea levels, coastal flood and extreme weather events worldwide.
Sasgen et al.
Scientists say that 2017 and 2018 will see unusually low ice melts due to colder summers and a high amount of snowfall, but data from 2019 revealed a return to extremely high melting rates.
The new satellite data are responsible for snowfall, which allows a more accurate calculation of net loss. Snowfall in 2019 was below average, contributing to the record high.
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 longer warm air over the area.
“After a two-year ‘breather’, in 2019 the mass loss increased sharply and exceeded all annual losses since 1948, and probably more than 100 years,” Sasgen said in a news release. “There are increasingly stable areas with high pressure over the ice sheet, which promote the inflow of warm air from the middle latitudes. We saw a similar pattern in the previous record year 2012.”
The Arctic is getting hot by 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 if six ice disappears, a new research found.
That is one of the most aggressive timelines to reach this threshold and, if correct, is one of the more direct signs that humans are expanding 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 decades.”
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