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The Arctic is sweltering. Earlier in June a town in the Arctic Circle recorded a temperature of 38 degrees Celsius – a worrying peak after one of the region’s mildest winters was followed by an unusually hot spring.
Elsewhere in the Arctic, the picture is even more concerning. Temperatures are rising faster than elsewhere on the planet, accelerating the decline of sea ice which in turns makes heating even more pronounced. And as that ice retreats, it risks releasing vast amounts of greenhouse gases that otherwise would remain locked within the ground.
The Arctic, with its sun-reflecting ice cap, has an outsized impact on the global climate but is slowly being pushed out of kilter by human-induced global heating. Here are six things you need to know as the Arctic sweats under an unusually severe summer heatwave.
The Arctic is facing its highest-ever temperatures
On June 20 a town in northeastern Siberia recorded what may be the highest ever temperature north of the Arctic Circle, if verified by the World Meteorological Organization. Verkhoyansk, which is located one degree north of the Arctic Circle, recorded a temperature of 38C – considerably above the average June high temperature for the town, which is 20C.
Although the Verkhoyansk temperature is yet to be confirmed, unusually high temperatures have been recorded across Siberia this year. The Copernicus Climate Change Service reported while May 2020 was the warmest May on record, temperature increases were even more pronounced in Siberia. Parts of the region saw temperatures that were up to 10C higher than usual. The unusually warm spring followed a very mild winter which saw higher than average temperatures particularly from January onwards.
Arctic sea ice hit its second-lowest recorded level in 2019
Sea ice cover in the Arctic ebbs and flows each year, usually hitting its minimum coverage in mid-September after the relative warmth of spring and summer. Last year, that minimum coverage dropped to 4.15 million square kilometres, which is tied with 2007 and 2016 as the second-lowest coverage since 1979, when humans started monitoring sea ice by satellite.
The only year with a lower minimum coverage was 2012, when the minimum ice extent reached 3.39 million square kilometers. The 13 lowest extents in the satellite era have all occurred in the last 13 years. Meanwhile, on March 5 the Arctic sea ice hit its annual maximum extent, reaching 15.05 million square kilometres, which is the eleventh-lowest maximum in the satellite era. The ten lowest maximum sea ice extremes have all occurred since 2006.
The Arctic is heating at more than twice the rate of the rest of the globe
In the last decade alone, the Arctic has heated by 0.75C, far outstripping the rate of heating in the rest of the globe. If global temperatures increase by 2C – a situation which is likely by 2100 even if current climate policies and pledges are followed – then the Arctic may see 4C mean annual warming, according to a paper in the journal Science Advances.
Since the late nineteenth century, the average global temperature has increased by 0.8C, while the Arctic has warmed by between two and three degrees Celsius over the same period. This warming and retreating sea ice is reducing the territory of Arctic animals and has sparked a race to access new sea routes and tap into the Arctic’s vast reserves of oil.
Melting sea ice triggers even more warming
Snow-covered sea ice plays an important role in regulating global temperatures. The white snow and ice reflect up to 85 per cent of sunlight. As the area covered by ice and snow decreases, it is replaced by dark seawater that absorbs much more sunlight, warming the ocean which then releases that warmth back into the air which raises atmospheric temperatures too. This positive feedback loop is largely the reason why the Arctic is heating at a much faster rate than the rest of the planet.
Zombie fires might be smouldering under the snow
Wildfires within the Arctic Circle are not uncommon, but last summer wildfires burned across the Arctic circle with an unprecedented intensity. But as the winter snows melted this year, it appeared that some of these Siberian wildfires reignited after smouldering under ice during winter.
An analysis by Thomas Smith at the London School of Economics conducted for New Scientist magazine found overlap between 2019 burn scars and new fires that appeared immediately after snow melted in 2020. While this is not conclusive evidence of ‘zombie’ fires, some of the observed areas were peatland, which is an important store of carbon and is known to smoulder over winter before reigniting in summer.
Melting permafrost could release huge amounts of methane into the atmosphere
The frozen sol of the Arctic permafrost contains one of the largest stores of organic carbon in the world. But as that soil starts to thaw, microbes can turn that stored carbon into carbon dioxide and methane that is released into the atmosphere and further heat the planet.
The release of methane is particularly worrying as the gas has 28 times the global warming potential as an equivalent amount of carbon dioxide. A Nasa study published in February 2020 found that there are two million methane hotspots dotted across some 30,000 square kilometres of the Arctic. Another Nasa study from August 2018 found that the gradual release of greenhouse gases may be dramatically sped-up by the middle of the 21st century due to a process known as abrupt thawing, which takes place under certain types of Arctic lakes.
Matt Reynolds is WIRED's science editor. He tweets from @mattsreynolds1
This article was originally published by WIRED UK
