The extreme weather that has brought snow and bitter cold to much of Europe in recent days is part of a remarkable temperature inversion that has also enveloped the Arctic with unprecedented warmth. This is the second time this winter that such unusual weather has hit the northern hemisphere. In January, the eastern US and Canada suffered a record-breaking “polar vortex” that brought plunging temperatures and led Niagara Falls to freeze. Now, as Europe experiences its most intense period of cold for eight years, temperatures at the North Pole have risen above the freezing point for several days — up to 30 degrees Celsius higher than normal for this time of year.
Both events may be a consequence of man-made climate change, scientists say, as rapid warming of the far north weakens the band of strong westerly winds that normally circulate around the Arctic. This makes it easier for very cold air to plunge thousands of miles south, while warm winds infiltrate polar regions. Scientists working for Nasa, the US space agency, say that heat and moisture are moving into the Arctic on two fronts this year — not only through the North Atlantic between Greenland and Europe as in the three previous winters but also from the Pacific through the Bering Strait.