Published: 2016-12-24 12:25:41 BdST
Friederike Otto, a senior researcher at Oxford's Environmental Change Institute told BBC News that in pre-industrial times "a heatwave like this would have been extremely rare - we would expect it to occur about every 1,000 years".
Temperatures are forecast to peak on Christmas Eve around the North Pole - at near-freezing.
The warm air from the North Atlantic is forecast to flow all the way to the North Pole via Spitsbergen, giving rise to clouds that prevent heat from escaping.
Forecasting models show that there is about a 2% chance of a heatwave event occurring every year.
Thorsten Markus, chief of NASA's Cryospheric Sciences Laboratory, said the heatwave was "very, very unusual".