Even as winter darkness descends across the Arctic, a year of record-breaking heat continues. Temperatures last weekend across the entire Arctic basin hit 12 degrees Fahrenheit above normal, scientists announced, with some areas measuring as high as 30 degrees F or more above the norm.
These extraordinary temperatures come on the heels of an exceptionally warm summer and fall in the Arctic that saw temperatures exceed 100 degrees F above the Arctic Circle in Siberia and cause an unprecedented delay in the Arctic Ocean refreezing this autumn. Indeed, the Northeast Passage along the Siberian coast remained navigable this year for a record 112 days until the route finally froze over earlier this month. That 112-day span shattered the previous record by about a month.
Satellite measurements show that the extent of sea ice covering the Arctic Ocean was the lowest ever recorded in October. That followed a September in the Arctic in which the sea ice minimum was the second-lowest on record since satellite monitoring began in 1979.
Scientists say that the strongest warming now occurring in the Arctic — a region heating up three times faster than the rest of the planet — is in the fall. That’s because rapidly disappearing sea ice, the volume of which has decreased by two-thirds in the past 40 years, is enabling the dark waters of the Arctic Ocean to absorb heat in the summer and then radiate it back into the atmosphere until deep into the fall.
Speaking of the exceptionally warm conditions this autumn, Zack Labe, an Arctic climate specialist at Colorado State University, said, “There is [still] a large area of open water that would normally be sea ice covered … The Arctic has transitioned from a state of old and thick sea ice to one with thin, first-year ice accompanied by rapidly warming ocean and air temperatures.”
Researchers say that Siberia’s extreme heat in 2020 would have been effectively impossible without human-caused climate change and was made at least 600 times more likely by human emissions of greenhouse gases.