Bitterly cold, icy, and inhospitable to almost all wild animals except polar bears.
If the Arctic is a medical patient, the National Oceanic and Atmospheric Administration’s (NOAA) Arctic Report Card is your annual physical exam, a comprehensive health check of this vast and important biome.
“We thought the changes would take a lot longer, and the models said they would,” said James Overland, an oceanographer at NOAA’s Pacific Marine Environmental Laboratory, who has been a part of the 15 Arctic Report Cards and is a co-author of the part about surface air temperatures in this issue.
“But the rate of change that we have seen in the last 20 years, and especially in the last five years, is beyond what we thought would happen.”
Here’s a look at the biggest changes seen in the Arctic this year and what they mean for the rest of the planet.
Extreme heat and waning ice
Scientists say that the Arctic is a benchmark for global climate.
As the planet warms from human emissions of greenhouse gases, the effects of that warming are felt here first, and heralds the changes that will occur in lower-latitude climates.
“Further south, in the lower 48 in the United States, we can handle a change of a couple of degrees in the air temperature,” Overland said.
“But potential changes in the Arctic that are three times what we see in mid-latitudes are going to completely change the look of the Arctic, and that will affect the rest of the planet.”
From shrinking sea ice and melting of the Greenland ice sheet, to melting permafrost and even changes in species distribution, many of the changes observed in the Arctic are being driven by rising temperatures. out of the air, Overland said.
The report found that last year was another abnormally hot in most of the region.
The period from October 2019 to September 2020 was the second hottest year in the last century for the Arctic, with surface temperatures 1.9 degrees Celsius warmer than the average from 1981 to 2010. Only 2016 saw higher temperatures That the last year.
Extreme heat was especially pronounced in Siberia, which saw sweltering temperatures 3 to 5 degrees Celsius above average during winter and spring.
Since 2000, the Arctic has warmed more than twice as fast as the rest of the planet, the report says.
All of this additional heat has affected another critical part of the Arctic ecosystem: its sea ice.
In addition to serving as a vital habitat for polar bears and walruses, Arctic sea ice is a key part of the planet’s air conditioning system, reflecting the sun’s energy back into space and keeping temperatures around the Pole cool. North.
But last year saw another near-record expanse of sea ice, another sign that this air conditioner is breaking down, scientists say.
Sea ice freezes in winter and melts in summer, and this year’s summer minimum extent was the second-lowest ever observed in the 42-year satellite record, according to the report.
The decreasing trend in the maximum winter sea ice extent also continued this year, with the March 2020 extent as the 11th lowest on record.
The 14 years from 2007 to 2020 have recorded the 14 lowest extents on record, and the extent of sea ice has decreased by about 13% per decade since 1979.
Now it’s no longer a question of “if” we’ll see an ice-free Arctic in the new decades, it’s “when,” said Walt Meier, senior research scientist at the National Snow and Ice Data Center and a co-author of the ice section. Marine from this year’s Arctic Report Card.
“For me, in my 50s, I thought (an ice-free Arctic in summer) would be something my grandchildren would probably live to see,” Meier said.
“But now, if I have a reasonably average life expectancy, I will probably live to see it, which is really tough in my opinion in terms of how quickly things have changed.”
A greener and less snowy Arctic
Snow still covers much of the Arctic for up to nine months out of the year. But that’s also changing, as warming leads to decreases in both the area of land and the time it’s buried in snow.
The extent of snow cover in June 2020 over the Eurasian Arctic was the lowest in a record 54 years, with the North American part of the region experiencing its 10th lowest extent.
That blanket of snow has also melted much earlier in parts of the region, especially Siberia, which saw record heat waves in 2020.
Although the report found that the length of snow cover was roughly normal over much of the Arctic, the snow cover over large swaths of Siberia had melted up to a month earlier, due to temperatures that were more than 5 degrees Celsius above the average.
Another effect of a warmer climate is that the Arctic is turning greener.
Tundra vegetation or “greenery” has been tracked by satellites since the early 1980s, and scientists monitor it as a key signal of changes in the region’s climate.
While “greenery” has declined dramatically in North America since 2016, it has remained above average on the Eurasian side.
And the report finds that, looking at the full satellite record, the general trend is moving toward a greener Arctic, as warmer temperatures melt the frozen tundra, allowing shrubs and other plant species to cast. roots in places where they couldn’t before.
Taken together, the changes described in the report show a region that is rapidly being transformed by warming caused by human activity.
“This is not just like a year of low sea ice or the melting of permafrost in a place where temperatures are rising, the whole ecosystem is changing,” Meier said.
“And that is telling you that this is not a fluke. It is something fundamental that is changing in the Arctic environment.”