An "unprecedented" number of wildfires are burning in the Arctic, producing as much greenhouse emissions in a month as some European countries do in a whole year.
The World Meteorological Organisation (WMO) said the hottest June on record saw more than 50 megatonnes of carbon released in fires inside the Arctic Circle - as much as Sweden produces in a year, and more than Junes from 2010 to 2018 combined.
"Although wildfires are common in the northern hemisphere between May and October, the latitude and intensity of these fires, as well as the length of time that they have been burning for, has been particularly unusual."
"The ongoing Arctic fires have been most severe in Alaska and Siberia, where some have been large enough to cover almost 100,000 football pitches... In Alberta, Canada, one fire is estimated to have been bigger than 300,000 pitches."
That's about 50 percent larger than Auckland.
"In Alaska alone, Copernicus Atmosphere Monitoring Service has registered almost 400 wildfires this year, with new ones igniting every day."
Satellite imagery posted by climate scientists to social media and by NASA's Earth Observatory showed smoke from the fires covering large parts of Siberia. NASA's Santiago Gassó said one "staggering" cloud of smoke was covering an area 17 times the size of New Zealand.
"The magnitude is unprecedented in the 16-year satellite record," London School of Economics environmental geography professor Thomas Smith told USA Today. "The fires appear to be further north than usual, and some appear to have ignited peat soils."
Peat fires can last for months, while forest blazes typically peter out in days, and release greenhouse gases - the kind of feedback loop scientists fear will see temperatures rise faster and faster as the century rolls on.
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Another 50 megatonnes had been released in the first three weeks of July - with little end in sight, because July is also on track to be the hottest ever recorded.
"The fires are burning through long-term carbon stores emitting greenhouse gases, which will further exacerbate greenhouse warming, leading to more fires," Smith said.
The WMO said temperatures in June were almost 10C higher than the average recorded between 1981 and 2010.
The polar regions are heating up faster than the rest of the planet.
"That heat is drying out forests and making them more susceptible to burn," the WMO said. "A recent study found Earth’s boreal forests are now burning at a rate unseen in at least 10,000 years."
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And while the clouds of smoke might temporarily block the sun's heat, the long-term effects are the reverse.
"Particles of smoke can land on snow and ice, causing the ice to absorb sunlight that it would otherwise reflect, and thereby accelerating the warming in the Arctic. Fires in the Arctic also increase the risk of further permafrost thawing that releases methane, which is also a greenhouse gas."
Research released earlier this week concluded climate fluctuations around the world over the past 2000 years were all local phenomena, and could not be compared to the recent worldwide spike in temperatures, which are undoubtedly linked to emissions caused by human activity.