Less than a week after US President Barack Obama and Canadian PM Justin Trudeau came together to block drilling in the Arctic and the Atlantic oceans, the Arctic experienced record high temperatures for the second time in as many months. 

Temperatures spiked in the days leading up to Christmas, the BBC reports, with Christmas Eve reportedly experiencing temperatures 20 degrees Celsius above average. On Dec. 22, temperatures at the North Pole pushed up above the freezing point, highly unusual for this time of year, given the average winter temperature at the North Pole is around -40 degrees Fahrenheit. 

Not quite freezing mark ... Santa's booze will stay chill up at the North Pole. 
20s °F is still mild for the top of the world. pic.twitter.com/ljuhwoIvRl

— Ryan Maue (@RyanMaue) December 20, 2016

Before the Industrial Revolution, “a heatwave like this would have been extremely rare,” Dr. Friederike Otto, a senior researcher at Oxford's Environmental Change Institute, told the BBC.  “We would expect it to occur about every 1,000 years.”  

Read more: The Arctic Is Now Safe From Drilling, Thanks to Obama and Trudeau

But now, given unprecedented melting of sea ice, the Arctic has experienced record-breaking temperatures in consecutive months. In November, temperatures in the Arctic were 36 degrees Fahrenheit above normal. 

Likewise, last year saw a massive heatwave hit the Arctic near Christmas, with temperatures nearing the freezing point in late December.

For the second year in a row, the Arctic is facing a late December heat wave https://t.co/c3n9UwXhjQpic.twitter.com/yZoaiAAUba

— Climate Central (@ClimateCentral) December 24, 2016

Arctic warming can be a difficult concept to grasp, especially as a warmer Arctic temperatures can coincide with colder temperatures in continental areas, the Washington Post reports. 

Some scientists have posited a theory of “Warm Arctic, Cold Continents,” which suggests that warmer Arctic temperatures can be accompanied by a “kind of swapping of the cold air masses of the Arctic with the warm air masses to the south of them.” 

Warm Arctic temperatures have come at the same time as abnormally cold ones on the eastern seaboard of the United States, such as the “polar vortex” of 2013-2014. 

Read more: The Arctic Is an Unbelievable 36 Degrees Above Normal

While scientists do not universally agree on the “Warm Arctic, Cold Continents” theory, they are worried about the possibility of consistently warmer temperatures in the Arctic. 

“If temperatures continue to increase further as they are now," Dr. Otto told the BBC, "we would expect a heatwave like this to occur every other year and that will be a huge stress on the ecosystem.” 

It’s possible that Arctic temps could climb as much as 50° F (about 28° C) above normal. On Christmas. #ThisIsFinehttps://t.co/qYnJP6F2xu

— Chris Tackett (@christackett) December 22, 2016