Greenland lost a record amount of ice during an extra warm 2019, with the melt massive enough to cover California in more than four feet (1.25 meters) of water, a new study said.
After two years when summer ice melting was minimal, last summer broke all records with 586 billion tons (532 billion metric tons) of ice melt, according to satellite measurements reported in a study Thursday. That is more than 140 trillion gallons (532 trillion liters) of water.
That is far more than the annual average loss of 259 billion tons (235 billion metric tons) since 2003 and easily surpasses the old record of 511 billion tons (464 billion metric tons) in 2012, said a study in Communications Earth & Environment. The study showed that in the 20th century there were many years when Greenland got ice.
“Not only is the Greenland ice sheet melting, but it is melting at a faster and faster pace,” said author Ingo Sasgen, a geoscientist at the Alfred Wegener Institute in Germany. Last Greenland’s melting year added 0.06 inches (1.5 millimeters) to global sea level rise. That sounds like a small amount, but “in our world it’s enormous, that’s amazing,” said co-author Alex Gardner, an ice scientist at NASA. Add more water from melting in other ice sheets and glaciers, along with an ocean that expands as it warms – and that translates into steadily rising sea levels, coastal flooding and other problems, he said.
While general records for ice melting in Greenland go back to 1948, scientists have had accurate records since 2003 of how much ice melts because NASA satellites measure the gravity of ice sheets. That’s the equivalent of putting the ice on a scale and weighing it as water flows, Gardner said.
As massive as the meltdown last year, the two years before that averaged about 108 billion tons (98 billion metric tons). “This shows that there is a second factor called Greenland blockade, which produces both supercharges and climate-related melting,” said Gardner.
In the summer, there are generally two factors in the weather in Greenland, Gardner said. Last year, Greenland blockade – a high pressure over Canada that changes the northern jet stream – caused warm southern air to come from the United States and Canada and flow into Greenland, causing more melting.
In 2017 and 2018, without Greenland, cooler Arctic air flowed from the open ocean to Greenland, making summer milder, he said.
This year, the summer melting of Greenland has not been so serious lately, closer to normal, 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 make sense. In her own study this month in the International Journal of Climatology, she found similar results and also calculated that Greenland’s coastal regions have averaged 3 degrees (1.7 degrees Celsius) in the summer since 1991.
“The fact that 2019 set an all-time record is very concerning,” said New York University ice scientist David Holland, who was not involved in any of the studies.
