‘The extraordinary years have become the normal years’: Scientists survey radical Arctic melt
A group of scientists studying a broad range of Arctic systems — from sea ice to permafrost to the Greenland ice sheet — gathered in D.C. Wednesday to lay out just how extreme a year 2016 has been so far for the northern cap of the planet.
“I see the situation as a train going downhill,” said Marco Tedesco, who studies Greenland at the Lamont-Doherty Earth Observatory at Columbia University. “And the feedback mechanisms in the Arctic [are] the slope of your hill. And it gets harder and harder to stop it.”
A series of researchers covering other Arctic systems then proceeded to tell very similar tales:
* For Greenland, April through June temperatures were about 3 degrees Celsius above the long-term average, said Tedesco — a new high. “The surface temperature set new records for April to June 2016,” he said. The peak moment for Greenland melting each year is right around now, and it isn’t clear whether the overall loss of water will match a staggering more than 500 billion tons in 2012, but it is already possible to say that “2016 is among the top years for melting,” Tedesco said.
* For Northern Hemisphere snow cover, the spring of 2016 set a new record low, said David Robinson, who runs the Rutgers University Global Snow Lab. “We lost the snow earlier than any time in record … throughout the Northern Hemisphere,” Robinson said.
* For thawing permafrost — carbon-packed soil layers that have the potential to spill even more greenhouse gases into the atmosphere as they warm — 2015 showed “record high temperatures” in measuring sites in Alaska, said Ted Schuur, who studies permafrost and wildfires at Arizona State University. But preliminary indicators, Shuur said, “point toward 2016 being a new record year.”
* For the Northern Hemisphere jet stream, which appears to be becoming more wavy and loopy in nature as the Arctic warms faster than the mid-latitudes, conditions in 2016 have once again been ripe for strange behavior, said Jennifer Francis, an Arctic researcher at Rutgers. “The difference in the temperature change between the Arctic and the mid-latitudes is at an all-time record high,” said Francis. “This is what we call Arctic amplification.”
The most troubling aspect of all of this, and a recurrent theme of the talks, was the researchers’ emphasis on how changes in the Arctic are not necessarily linear in nature as global warming grows — once you cross the freezing point, notes Robinson, it’s a total phase change for water, plain and simple — and that the system is laden with feedback processes, which amplify themselves