Record warmth in the Arctic has scientists struggling to explain the breadth and impact of human influence on the climate, Jason Samenow reports for The Washington Post.

2016 was the hottest year on record, breaking the previous record held by 2015, which broke the previous record held by 2014. Together with record low sea ice, these statistics are leaving veteran Arctic scientists stunned, Samenow explains.

“[A]fter studying the Arctic and its climate for three and a half decades, I have concluded that what has happened over the last year goes beyond even the extreme,” wrote Mark Serreze, director of the National Snow and Ice Data Center in Boulder, Colo., in an essay for Earth magazine.

Image: Global average temperature departures from the 20th century average | Image Credit: NASA