A study just published in Nature Climate Change reports an "exceptional" weakening of the Gulf Stream system across the twentieth century, and suggests that the entire system of the Atlantic Meridional Overturning Circulation is in jeopardy. But the lack of measurements means that the degree to which this is true is unclear. The weakening of the system is the probable cause of the recent harsh winters in North America, as the polar vortex has ceased to be held in position by warm air that is normally driven northward by the current.
Sudden stratospheric warming has split the polar vortex in two. The polar vortex, which forms as the atmosphere loses heat to space in long Arctic winter night, was split in two by massive heating from below, as a series of intense storms in the far north Pacific intensified. Energy went upwards from the lower atmosphere around the Himalayas and Tibetan Plateau and broke into the stratosphere, causing major sudden warming.
But wouldn’t that make it warmer instead of colder? Surprisingly, no–this creates SEVERE winter weather.
Over the past 15 years, a mass of fresh water from ice melt has been building under the Arctic ice cap. The water is trapped under the Beaufort Gyre in the western Arctic, and presently represents about 10% of all the fresh water in the Arctic. It appears in the form of a bulge under the ice, and is kept in place by the permanent anti-cyclonic winds that blow around the gyre. The water is coming from melt-swollen Siberian rivers, and the bulge is growing by about six inches a year, meaning that billions of gallons of water are continuing to accumulate in it.
More proof our weather is out of whack: When it’s winter in the US and Europe, it’s summer in Australia, which normally has temperatures of around 86 degrees Fahrenheit at this time of year, but just like the UK, this country finds itself plunged into a blizzard. The equivalent to this would be if the US experienced Christmas weather in July.
In the Telegraph, Bonnie Malkin quotes hotel manager Michelle Lovius as saying, "First thing this morning everything was just very still, very peaceful and every single thing was just blanketed in a thick cover of white."