An extended heat wave that has been baking the Russian Arctic for months drove the temperature in Verkhoyansk, Russia—north of the Arctic Circle—to 100.4°F on June 20, the official first day of summer in the Northern Hemisphere. This record high temperature is a signal of a rapidly and continually warming planet, and a preview of how Arctic warming will continue in an increasingly hot future, scientists say.
“For a long time, we’ve been saying we’re going to get more extremes like strong heat waves,” says Ruth Mottram, a climate scientist at the Danish Meteorological Institute. “It’s a little like the projections are coming true, and sooner than we might have thought.”
Saturday’s record wasn’t just a quick spike before a return to more normal summer temperatures for the Russian Arctic: The heat wave behind it is projected to continue for at least another week. It was the hottest temperature ever recorded in the town, where records have been kept since 1885.
Hot summer days aren’t unheard of in the Arctic. The ocean-tempered coasts tend to stay slightly cooler, but inland, summer temperatures sometimes soar. Fort Yukon, Alaska, recorded the first-ever 100°F (37.7°C) day north of the Arctic Circle in 1915; Verkhoyansk hit 99.1°F (37.3°C) in 1988.
“At this time of the year, around the summer solstice, you get 24 hours of sunlight,” says Walt Meier, a climate scientist at the National Snow and Ice Data Center. “That’s a lot of solar energy coming in. So in these high-latitude areas—80 degrees, 90 degrees, that’s not unheard of.”
But climate change is “loading the dice” toward extreme temperatures like the one recorded this week, he says. The Arctic is warming more than twice as fast as the rest of the planet: Baseline warmth in the high Arctic has increased by between 3.6 to 5.4°F(2 to 3°C) over the past hundred or so years. About 0.75°C of that has occurred in the last decade alone. (Find out more about climate change and how humans are causing it.)
That means any heat waves that hit the region are strengthened by the extra warming. So the average warmness of a summer increases, and the extremes do too.
This month’s super-hot day emerged from a potent mix of factors. First, climate change nudged base temperatures up. Then, western Siberia experienced one of its hottest-ever spring seasons, according to climate scientists at the EU’s Copernicus Climate Change Service. Since December, air temperatures in the region have averaged nearly 11°F (6°C) above the average seen between 1979 and 2019. The high heat is also likely well above the average seen in any similar six-month stretch going back to 1880. In May, air temperatures hovered some 18°F (10°C) above the “normal” May average of 33.8°F (1°C )—something that would be likely to occur only once in 100,000 years, if human-caused climate change hadn’t thrown a wrench in the climate system’s plumbing.
“It has been really bizarre to see,” says Ivana Cvijanovic, a climate scientist at the Barcelona Supercomputing Center. “All across Siberia, it has really been so hot for so long. January, then February, then March, then April. The pattern—it really stands out.”
The warm winter and hot spring meant that the snow usually blanketing the ground across much of the region melted about a month earlier than normal. Bright white snow plays a crucial role in keeping parts of the Arctic cool, by reflecting the sun’s incoming heat. Once it had gone away, dirt and plants readily soaked up the heat instead.
Then, the weather conditions aligned. A big, high-pressure system settled into place over western Siberia, where it stalled. These kinds of systems often have clear, cloudless skies—perfect for solar heat to shine through unobstructed, straight onto the hot Siberian ground.
“The air is just kind of trapped there; it’s like an oven sitting over the area, just heating it up more and more the longer it sits there,” says Meier.
In recent years, the effects of these kinds of immobile heat waves have become more obvious across the Arctic. In 2012, 97 percent of the Greenland ice sheet’s surface got so warm it turned essentially to slush. In 2016, it was so warm in High Arctic Svalbard, Norway, that rain fell instead of snow for part of the winter. Last summer, the edges of the Greenland ice sheet experienced up to three extra months of melting weather. Limpid blue pools formed on its surface; floods of melt gushed off the edge of the continent, and fires broke out in its sparse landscapes after a heat wave parked over the island for weeks.
There’s a lively scientific debate underway about whether these kinds of heat waves in the high latitudes are lasting longer or becoming more frequent than they were in the past because of climate change. But there’s little debate that the future holds much more extreme heat for the Arctic. Winter average temperatures in the Arctic have already exceeded the 3.6°F (2°C) threshold stated in the Paris climate agreement; predictions suggest the annual average temperature for the region will exceed that within decades.
"By 2100, under an extreme warming scenario, we would expect to see an event like this every year," says Robert Rohde, a climate scientist with Berkeley Earth.
Similar patterns are playing out at the southern pole, too. A site on the Antarctic Peninsula hit nearly 65°F (18.3°C) during January, its summertime.
Polar amplification and human fingerprints
The poles are warming up more quickly than the rest of Earth because of a phenomenon called “polar amplification.” The sea ice that used to blanket much of the Arctic Ocean provided a bright white cap across the northernmost reaches of the planet. Like the snow that reflects incoming solar radiation in Siberia, the ice bounced the sun’s heat back toward space.
But as Earth has warmed, there’s less sea ice covering the Arctic Ocean, leaving behind dark waters that absorb much more heat. Sea ice forms less readily in that warm water, leading the water to absorb even more solar heat, and the system goes on a self-reinforcing loop.
It’s difficult to say for sure that this or that single heat wave was worse because of climate change—and no one has yet done that analysis for this stretch of excessive Siberian warmth. But researchers found human-caused climate change’s fingerprints all over the heat wave that caused excessive melting in Greenland and across northern Europe last summer. 2019’s June heat—which caused temperatures in France to spike above 113°F (45°C), was at least five times more likely to occur because of human impacts. And some 60 percent of 2016’s excessive Arctic heat was attributable to human-caused climate change, scientists found.
Fires, oil spills
This season’s hot weather comes with consequences. Below the ground, much of the Russian Arctic is covered in permafrost, carbon-rich peat soils capped by a layer of ice that usually stays frozen for most or all of the year. But hot air temperatures destabilize the frozen ground and lead to often irreparable change.
In June, defrosted soils may have led to the collapse of a diesel storage tank in Siberia, spilling 20,000 metric tons of fuel into a nearby river. A recent study suggests that this is far from an isolated risk: By 2050, scientists say, vast amounts of infrastructure across the Arctic are at risk from thawing ground collapsing beneath them. Thousands of miles of pipelines and roads, buildings and storage tanks, oil fields and airports, and more, all potentially destabilized by overheated weather that has melted the ground.
Fires have also been smoldering across the Russian Arctic. The overwarm spring dried out both soils and vegetation, leaving them primed to burn, and over 12 million acres were on fire as of early June, according to Russia’s forest service.
“There’s lot and lots of vegetation and forest across Siberia,” says Meier. “And when it’s hot like this for so long, it dries out and becomes like a tinderbox