Temperatures in the Siberian Arctic reached record averages in June, with some areas seeing rises of as much as 10C (18F), according to EU data.
Scientists say the heat has helped fan wildfires in the region, resulting in the unprecedented estimated release of 59m tonnes of carbon dioxide.
Hot summer weather is not uncommon in the Arctic Circle, but recent months have seen abnormally high temperatures.
The Arctic is believed to be warming twice as fast as the global average.
Carlo Buontempo, director of the European Union’s earth observation programme, the Copernicus Climate Change Service, said the trend was “worrisome”.
Copernicus scientists say the region saw an average rise of 5C. That is more than a degree higher than the previous two warmest Junes on record – in 2018 and 2019.
One Siberian town, Verkhoyansk, reached a high of 38C on 20 June – 18C higher than the average maximum daily temperature for the month. The record is still to be verified.
Earlier in June, parts of Siberia recorded 30C, while in May, Khatanga in Russia – situated in the Arctic Circle at 72 degrees north – set a new May temperature record of 25.4C.
Meanwhile, some 246 fires covering more than 1,400 sq km (540 sq miles) were recorded in the region to 6 July, according to the Russian forestry agency.
The two issues are related, according to Mark Parrington, a senior scientist at Copernicus.
“Higher temperatures and drier surface conditions are providing ideal conditions for these fires to burn and to persist for so long over such a large area,” he told news agency Reuters.