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Greenland lost a record amount of ice in a very hot 2019, with the melt massive enough to cover California in more than 1.25 meters of water, according to a new study.
After two years of minimal summer ice melt, last summer shattered all records with 586 billion tonnes (532 billion metric tonnes) of ice melt, according to satellite measurements reported in a study Thursday. That’s over 140 trillion gallons (532 trillion liters) of water.
That’s far more than the average annual loss of 259 billion tonnes (235 billion metric tonnes) since 2003 and easily surpasses the old record of 511 billion tonnes (464 billion metric tonnes) in 2012, according to a study by Nature Communications Earth & Environment. The study showed that in the 20th century, Greenland gained ice for many years.
“Not only is the Greenland ice sheet melting, it’s melting at an increasingly rapid rate,” said lead study author Ingo Sasgen, a geoscientist at the Alfred Wegener Institute in Germany.
Last year’s Greenland melt added 0.06 inches (1.5 millimeters) to the global sea-level rise. It seems minimal, but “in our world it’s huge, it’s huge. staggering, ”said study co-author Alex Gardner, a NASA ice scientist. Add in more water from melting other ice caps and glaciers, plus an ocean that expands as it warms – and that translates into slow sea level rise, coastal flooding and other issues, he said.
While general records of ice melt in Greenland date back to 1948, scientists since 2003 have had accurate records of how much ice has melted because NASA satellites measure the gravity of ice caps. It’s the equivalent of putting ice on a scale and weighing it as the water flows, Gardner said.
As massive as last year’s melt was, the previous two years averaged only around 108 billion tonnes (98 billion tonnes). This shows that there is a second factor called blocking Greenland, which either super-charges or mitigates climate-related melt, Gardner said.
In summer, there are usually two factors in Greenland’s climate, Gardner said. Last year, the blockade of Greenland – high pressure on Canada that alters the northern jet stream – caused warm air to rise from the southern United States and Canada to Greenland, causing resulted in increased melting.
In 2017 and 2018, without the Greenland blockage, cooler arctic air flowed from the open ocean to Greenland, making the summer milder, he said.
This year, Greenland’s summer melt has not been as severe, closer to normal lately, said Ruth Mottram, an ice scientist at the Danish Meteorological Institute, who was not part of Sasgen’s research. .
Mottram and several other outside scientists said Sasgen’s calculations made sense. In his own study this month in the International Journal of Climatology, she found similar results and also calculated that the coastal regions of Greenland have warmed by an average of 3 degrees (1.7 degrees Celsius) in summer since 1991.
“The fact that 2019 set an all-time record is of great concern,” said New York University ice scientist David Holland, who was not part of either study.
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Follow Seth Borenstein on Twitter at @borenbears .
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