The Arctic is warming and changing rapidly, with record or near-record conditions documented across the region in 2020. That's according to an international team of 133 researchers from over a dozen countries who contributed to the 15th annual NOAA Arctic Report Card, released on Tuesday.
The report is a comprehensive year-in-review of Arctic conditions — what NOAA calls vital signs — that characterize the health and stability of the Arctic ecosystem. They include variables like air temperature, sea ice and wildland fires. While climate conditions in this frigid part of the world typically change naturally at a glacial pace, in recent years the transformation has been occurring at a breakneck speed.
In a video accompanying the report, NOAA says there have been "alarming rates of change observed" since the 2006 Arctic Report Card, and adds, "the rate of change has been extraordinary."
This is evidenced by the intense heat and wildfires in Siberia this summer. It's not often that events deep in rural Arctic territory make headlines around the world, but in late June, for the first time on record, the temperature soared past the 100-degree Fahrenheit mark above the Arctic Circle, in a town called Verkhoyansk. That was part of a several months long heat event which climate scientists said was made 600 times more likely by human-caused climate change.
From October 2019 to September 2020, Arctic surface temperatures were the second warmest on record — almost 2 degrees Celsius (3.6 degrees Fahrenheit) above the 1980-2010 normal average — behind only 2016, a year affected by a very strong global El Niño event.
The cause of the rapid warming is straightforward and well understood: It is human-caused climate change. But in the Arctic, the pace of warming is 2 to 3 times the global average — a phenomenon known as Arctic amplification.
According to the report, the sea-ice extent at the end of the summer in 2020 was the second lowest in the 42-year satellite record, behind only the summer of 2012, a summer characterized by unusual stormy conditions which breaks up ice. But this October, when sea-ice typically rebounds quickly, it did not, dropping to the lowest levels on record.
October 2020 sea-ice volume also recorded the lowest value on record. The ice was so thin that Russia was not able to find thick enough ice to test its new nuclear-powered ice-breaker ship. This drop is ice volume is part of a long-term trend in which sea-ice volume, due primarily to declines in ice thickness, has dropped by two-thirds since the 1970s.
This dramatic drop in Arctic ice is the main driver for rapid Arctic changes.
Large expanses of sea-ice, and to a lesser degree snow, stabilize the Arctic climate by regulating air and ocean temperatures. The white shading reflects sunlight back to space, limiting heating. But as temperatures have continued to climb over the past few decades, ice cover has diminished rapidly, exposing typically more of the darker-colored ocean and land. That darker surface is absorbing more heat, leading to warmer temperatures and more melting.
This does not represent a mere subtle shift in the way the system works — it is a dramatic change. The way in which ice regulates the climate versus exposed land and ocean is drastically different. Not only does the exposed area absorb more heat, it also allows ocean and air currents to penetrate deeper into the Arctic, allowing warmth from southern latitudes to invade.
Rick Thoman is an Alaskan climate specialist from the University of Alaska, Fairbanks, and co-author of the report. He says the systemic changes occurring in the Arctic should raise eyebrows to the south, because they foreshadow what may be in store for the rest of us.
"The Arctic continues to sound the bell as a warning to lower latitudes on how rapidly things can change when thresholds are crossed," said Thoman. "The thresholds will not be the same, of course, but the Arctic is living proof that major environmental change need not proceed gradually over generations."
One major environmental change is the rapid loss of permafrost along the coast. Since the early 2000s, erosion of coastal permafrost (partially frozen ground) in the Arctic has increased everywhere. Along the U.S. and Canadian Beaufort Sea, erosion rates increased by 80% to 160% when compared with data from several decades ago.
It may seem counterintuitive, but snow accumulation during the 2019-20 winter was above normal across the entire Arctic. However, this makes sense because a warmer atmosphere holds more moisture, dumping more snow, as long as the air temperatures are still near or below freezing.
With that said, the exceptional spring warmth across the Eurasian Arctic still resulted in the lowest June snow cover extent in this region since the observational record began in 1967. And this drop in late spring snow cover is not just confined to 2020. Since 1981, June Arctic snow cover extent is decreasing at a rate of 15% per decade.
Variability in seasonal snow cover is an important control on wildland fire activity in high northern latitudes, and as a consequence of dwindling spring and summer snow cover, wildfires are escalating in the Arctic. In 2020, record-setting Arctic fires — mainly in the boreal forest of Siberia — emitted 35% more carbon dioxide than the year before, which was also a record-breaker.
These more intense wildfires are due to the drying out of accumulated layers of partially decomposed organic matter by prolonged warm, dry conditions, like the ones observed this year in Siberia. This provides a high-octane fuel source.
The report says, "Increasing trends in air temperature and fuel availability over the 41-year record (1979-2019) suggest that conditions are becoming more favorable for fire growth, with more intense burning, more fire growth episodes, and greater consumption of fuels."
The changes are not only being experienced on land, but also in the Arctic Ocean. Sea surface temperatures this summer were 1 to 3 degrees Celsius (2 to 5 degrees Fahrenheit) above normal.
The abnormally warm water is one of the reasons sea-ice took so long to regrow this fall.
But this warmer water also comes with some positive biological impacts. NOAA reports that ocean primary productivity — a technical term for the amount of life, like plankton — in the Laptev Sea near Siberia was 2 to 6 times higher than normal. Benefitting from this increase in biological activity are bowhead whales, a staple resource for coastal Indigenous people from Russia to Greenland. Over the past 30 years the bowhead whale population has increased, partly due to increases in Arctic Ocean life.
While there are those rare examples of positive impacts, most of the changes are happening so fast that they are destabilizing for Indigenous populations, ecosystems and for weather and climate patterns. And Thoman says the Arctic will not be settling into a "new normal," or back to what used to be considered normal, anytime soon, because the only constant at the moment in the Arctic is change.
"Because the Arctic changes are intimately tied with ice and snow changes, and these are positive feedback loops, this is not something that can be reversed with one cold winter (multi-year ice takes, well, multiple years to grow)," explains Thoman. "It would take generations for 'frozen Arctic' like the, say, 1960s to return, and some things, like permafrost in some areas, would take far longer to regrow."
First published on December 8, 2020 / 8:37 PM
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