A prolonged heatwave in Siberia is “undoubtedly alarming”, climate scientists have said. The freak temperatures have been linked to wildfires, a huge oil spill and a plague of tree-eating moths.

Smoke from wildfires in Siberia drifted to Alaska last year as well, according to the National Weather Service, but Alaska already had hazy skies from local wildfires.

Much of Siberia this year has had unseasonably high temperatures, leading to sizable wildfires.

The wildfires can burrow into rich organic material, such as the vast peatlands that ring the Arctic, and smolder under the snowpack throughout the frigid winter.

Gallery | The forest fires have covered an area larger than Greece and are emitting black smog that harms nearby populations.