In 2015, he. But a new NASA study reveals that the Greenland Glacier, which was one of the world's fastest shrinking ice and snow masses, is growing again.
Six years ago, the Jakobshavn Glacier retreated about 1.8 kilometers and thinned by nearly 30 meters a year, but it has begun to grow at about the same pace over the last two years, according to a published study. Monday in Nature Geoscience. The study's authors and outside scientists think that it is temporary.
"It was a bit of a surprise, we kind of got used to a frantic system," said Jason Box, a geology researcher in Denmark and Greenland. "The good news is that it reminds you that it does not necessarily go that fast, but it's okay."
Box, which was not part of the study, said that Jakobshavn was "arguably the largest glacier in Greenland because it releases the largest amount of ice in the northern hemisphere." For all of Greenland he is king ".
The natural cyclic cooling of the waters of the North Atlantic has probably caused the glacier to reverse its trajectory, said the study's lead author, Ala Khazendar, NASA's glaciologist in charge of the Oceans Melting Project. Greenland (OMG). Khazendar and his colleagues say that this coincides with a reversal of the North Atlantic Oscillation – a natural and temporary cooling and warming of parts of the ocean that are like a distant cousin of the ocean. El Nino in the Pacific.
The water of Disko Bay, where Jakobshavn flows into the ocean, is about 3 degrees colder (2 degrees Celsius) than a few years ago, said the authors of the 39; study.
Although this is a "good news" on a temporary basis, it is bad news in the long run because it tells scientists that the temperature of the ocean is a more important factor in retreats and glacier progress that we previously thought, said NASA climatologist Josh Willis. -author. Over the decades, global warming has caused a warming of the water, he said, pointing out that about 90% of the heat trapped by greenhouse gases is released into the oceans.
"In the long run, we will probably have to raise our sea level rise forecasts," Willis said.
Think of the temperature of the ocean near Greenland as an escalator slowly rising from global warming, said Khazendar. But sometimes, the natural oscillation in the North Atlantic is like jumping a few steps or jumping a few steps. The water can become colder and have effects, but in the long run it gets warmer and the melt will get worse, he said.
Four outside scientists said that the study and the results made sense.
Ian Joughin, an ice science scientist from the University of Washington, who did not participate in the study and who predicted such a change seven years ago, said it would be a "big mistake" "to interpret the latest data as conflicting with the science of climate change.
What is happening, Joughin said, is "to a large extent, a temporary shock." Declines are occurring in the stock market, but overall, the long-term trajectory is on the rise. is really the same thing. "