The ill winds of climate change are irrevocably reshaping the Arctic, including massive declines in sea ice and snow and a record-late start to sea ice formation this fall. Those were the sobering conclusions of the 2016 Arctic Report Card released Tuesday.
The report card is sponsored by the National Oceanic and Atmospheric Administration (NOAA) and co-authored by more than 50 scientists from Asia, North America and Europe. The data shows that the Arctic is warming at double the rate of the global average temperature. Between October 2015 and September 2016, temperatures over Arctic land areas were 2.0 degrees Celsius above the 1981-2010 baseline, the warmest on record going back to 1900.
The report, released at the American Geophysical Union meeting in San Francisco, clearly links the Arctic heatwave to a record-late start to formation of sea ice this fall, and to record high and low seasonal snow cover extent in the Northern Hemisphere. If the extreme warmth recorded in the Arctic this fall persists for the next few years, it may signal a completely new climate in the region, scientists said.
Jeremy Mathis, director of NOAA's Arctic Research Program, said the report highlights the clear and pronounced global warming signal in the Arctic and its effects cascading throughout the environment, like the spread of parasitic diseases in Arctic animals.
"We've seen a year in 2016 like we've never seen before ... with clear acceleration of many global warming signals. The Arctic was whispering change. Now it's not whispering. It's speaking, it's shouting change, and the changes are large," said co-author Donald Perovich, who studies Arctic climate at Dartmouth College.
Sustained observations of the Arctic is crucial to making science-based policy decisions, he added, a goal threatened by the inclusion of numerous climate deniers in President-elect Donald Trump's cabinet. This week, Trump's transition team posted a new "Energy Independence" website that repeats his previous intentions to open up vast areas for fossil fuel development and to scrap existing climate action plans.
Arctic ice doesn't care about politics, and what happens in the region now is critically important to the U.S., said Rafe Pomerance, chair of Arctic 21 and a member of the Polar Research Board of the National Academies of Sciences, Engineering and Medicine.
"What kind of Arctic do we want to have? It has to be one that maintains the stability of the climate system," he said. "The melting of Greenland is going to put an enormous hit on real estate values. The fate of Greenland is the fate of Miami. It's in the U.S. national interest to stop Greenland's ice sheet from melting. How are we going to bring it to a halt?"
The scientific report stands in stark contrast to the incoming administration's apparent intention to foster more fossil fuel development, he said.
"This is a byproduct of the poison of denialism, a political issue that has taken hold so deeply so that this is the kind of stuff that can be contemplated," he said. "Evidence doesn't mean anything, science doesn't seem to mean anything. They ought to take what's going on in the Arctic really seriously. This is a crisis. The Arctic is unraveling."
The report card underscores nearly a year of unusual conditions, said Lars Kaleschke, an Arctic researcher at the University of Hamburg who was not among the report's authors. Extremely warm air temperatures last January and February led to the smallest maximum winter sea ice extent on record, equaling the record set in 2015. And the return of extreme warmth in November led to a short period of ice retreat at a time when it's usually growing fast.
Kaleschke said he's become concerned by reports that the incoming U.S. administration may cut NASA's Earth observation budget, which includes many programs critical to understanding Arctic global warming changes.
"That would be a huge loss for the climate research community," he said. Those programs are critical to efforts to understand rapid Arctic changes. NASA's airborne IceBridge program, for example, helps confirm ice thickness measurements made by the European Space Agency's CryoSat program.
Kaleschke said Trump appears to have a clear anti-science attitude that will affect the world's ability to respond to climate change.
The global warming signal was particularly evident in Greenland in 2016, said Marco Tedesco, a climate researcher with Columbia University's Lamont-Doherty Earth Observatory who was involved in the report.
"The Greenland Ice Sheet continued to lose mass in 2016. The melt onset was the second earliest and the melt season was 30 to 40 days longer than average in the northeast, he said. Spring snow cover extent in Greenland and other parts of the Arctic reached new record lows in spring and there's new evidence that snow depth is also decreasing, which would be a precursor to even earlier and faster melting."
Arctic permafrost is also releasing more greenhouse gases in the winter than plants can take up in the summer, making the Arctic a net source of heat-trapping pollution, he added.
Snow cover on land helps cool the entire Northern Hemisphere climate system, insulates soil and regulates the water cycle through the seasons.
Highlighting the the recent changes in the Arctic is even more important in light of the current political context, said University of Sheffield geographer Edward Hanna, who co-authored the report's chapter on air surface temperatures.
Air temperatures across the Arctic between January and March 2016 soared past previous record highs, with some locations reporting anomalies of more than 8 degrees Celsius. In recent decades, there have been more frequent surges of warm air from mid-latitudes far north into the Arctic. That lends support to the emerging hypothesis that the Arctic meltdown is changing the path of the jet stream, possibly leading to more sustained extreme weather events in the Northern Hemisphere, Hanna said.
The steady trend toward thinner, younger ice in the Arctic is also notable, suggesting the meltdown is irreversible.
"It's hard to see how the summer sea ice will survive," he concluded.