Extreme heat events are happening at both of Earth’s poles at the same time, with parts of Antarctica more than 40C warmer than average and areas of the Arctic more than 30C hotter than usual.
Weather stations in Antarctica shattered records on Friday as the region neared autumn.
The Concordia station was warmer than average at -12.2C. Meanwhile, the Vostok station higher up stood at -17.7C, beating its all-time record by about 15C, according to a tweet from extreme weather record tracker Maximiliano Herrera.
The coastal Terra Nova Base was far above freezing at 7C.
It caught officials at the National Snow and Ice Data Centre in Boulder, Colorado, by surprise because they were paying attention to the Arctic where it was around 10C warmer than average and areas around the North Pole were nearing or at the melting point.
Walt Meier, an ice scientist from the centre said: “They are opposite seasons. You don’t see the north and the south [poles] both melting at the same time.”
He added: “It’s definitely an unusual occurrence.”
University of Wisconsin meteorologist Matthew Lazzara monitors temperatures at East Antarctica’s Dome C-ii and logged -10C on Friday, when the normal temperature is -43C.
“That’s a temperature that you should see in January, not March. January is summer there. That’s dramatic,” he said.
Both scientists said what happened in Antarctica was probably just a random weather event and not a sign of the climate crisis.
But if it happens again or repeatedly then it might be something to worry about and part of global warming, they said.
The Antarctic continent as a whole on Friday was 4.8C warmer than a baseline temperature between 1979 and 2000, according to the University of Maine’s Climate Reanalyser, based on US National Oceanic Atmospheric Administration weather models.
That level of heating over an already warmed-up average was unusual, Mr Meier said.
At the same time, on Friday the Arctic as a whole was 3.3C warmer than the 1979 to 2000 average.
By comparison, the world as a whole was only 0.6C above the 1979 to 2000 average.
In the Arctic, which has been warming two to three times faster than the rest of the globe and is considered vulnerable to the climate crisis, warm Atlantic air was coming north off the coast of Greenland.
What makes the Antarctic warming noteworthy is the southern continent — except for its vulnerable peninsula which is warming quickly and losing ice rapidly — has not been warming much, especially when compared to the rest of the globe, Mr Meier from the US National Snow and Ice Data Centre said.
In February, the Antarctic sea ice extent - the area of ice that covers the ocean at a given time - reached a record low at 830,000 square miles, which was nearly 30 per cent below average.
Additional reporting by Associated Press