A freak warming around the North Pole is sending a blast of Arctic cold over Europe in a sign of "wacky" weather that may happen more often with man-made global warming.
Scientists say the northern tip of Greenland has had a record-smashing 61 hours of temperatures above freezing so far this year, linked to a rare retreat of sea ice in the Arctic winter darkness.
Arctic Ocean sea ice is at a record low for late February, at 14.1 million square kilometres. That is about a million square kilometres less than normal, or roughly the size of Egypt.
Around the entire Arctic region, temperatures are now about 20C above normal, at minus 8C.
So what's causing Arctic warming?
Head of UN Environment, Erik Solheim, says the rare weather fits a wider pattern driven by a build-up of greenhouse gases, mainly from burning fossil fuels from cars, factories and power plants.
He says we only have a short amount of time to stop it from getting significantly worse.
According to scientists, the risk of an ice-free Arctic in summer is about 50 per cent higher.
As long ago as 1973, a study suggested an ice-free Arctic Ocean could make regions further south colder.
University of Hamburg professor Lars Kaleschke tweeted the "warm Arctic, cold continent" weather pattern continued with "scary strength and persistence".
He says the question is whether this will start to happen more often.
Scientists say a long-term shrinking of sea ice on the Arctic Ocean, linked to global warming, exposes warmer water below that releases more heat into the atmosphere.
That in turn may be disrupting the high altitude jet stream, meaning colder air can penetrate further south and warmer air further north.
The big problem in figuring out whether the Arctic warmth is driven by human activities or natural variations is a lack of measuring stations.
The 'Beast from the East'
The World Meteorological Organisation says the chill in Europe is caused by a "sudden stratospheric warming" above the North Pole that led to a split in the polar vortex, a cold area of air above the Arctic that spilled cold south.
The Arctic storm dubbed the "Beast from the East" saw temperatures across much of Europe fall on Monday to their lowest level this winter and even brought a rare snowstorm to Rome, paralysing the city.
The cold weather has caused chaos, and Italian authorities even called the army to help clear the streets.
The Siberian weather system brought with it strong winds and the coldest temperatures for years to many regions.
Scientists say the big chill is partly caused by the fact that strong winds which normally keep cold air "locked" over the Arctic have weakened, releasing icy blasts across the northern hemisphere.
The freeze will last all week
The World Meteorological Organisation says daily minimum temperatures below 0C were expected, even in southern Europe.
The Siberian weather system, which is slowly moving across the continent, is causing several places to feel as cold as the Arctic Circle.
Rome has experienced its heaviest February snowfall in decades, it got down to minus 27C on Germany's highest mountain and weather forecasters are warning Britain could cop blizzards before the end of the week.
Icy blasts could become more frequent
Elsewhere in Europe, the storm set dangerously low temperatures, with some places in Lithuania dropping to a low of 24C.
The weather was blamed for at least three deaths on the weekend.
Similar sudden drops have occurred over North America in recent years and climate researchers say they could become more common as global warming further saps strength from the air currents around the pole.