World's weird weather: How polar vortex is creating topsy-turvy temperatures in northern hemisphere

All across the northern hemisphere from Athens, Greece, to Athens, Texas, snowfalls have blanketed streets and temperatures have plunged to freezing in places where winter usually requires no more than a jacket. 

Snow has covered nearly three quarters of the United States, to an average depth of six inches, compared to 35.5 per cent last year with an average depth of 4.6 inches. 

In Moscow cars have been submerged under snowdrifts in the biggest dump to hit the Russian capital since 1973, while comparatively warmer cities like Madrid, Istanbul and Rome, have also been covered in white. 

Around the North Pole, winter’s ultra-cold air is usually kept bottled up 15 to 30 miles high. That’s the polar vortex, which spins like a whirling top at the top of the planet. 

The polar vortex is usually held in place by the jet stream which meanders around the northern hemisphere, around 20 miles south of the polar vortex.

But sometimes the jet stream and the polar vortex weaken, meaning that the freezing Arctic air plunges southwards into areas of North America and Europe which are generally warmer during the winter.

It also means that places which are normally very cold in the winter, like Alaska and Greenland, feel comparatively warmer as the jet stream moves northwards.  

It’s been happening more often, and scientists are still not completely sure why, some say it is a natural random weather pattern while others claim that it has been caused by man-made climate change.  

Meteorologists say that this particular polar vortex is one of the nastiest and largest they have seen since records began in the late 1950s.

The white-outs at the Hagia Sophia and the Acropolis this week began as part of a pattern going back to January, which also covered the United Kingdom in snow.   

Record subzero temperatures have knocked millions off the power grid in Athens, Greece, and in Oklahoma and Texas in the United States.

Icy tornadoes have ripped across America which left three people dead in North Carolina on Tuesday.

Huge snow dumps were not just recorded in the States, but in Greece and Turkey this week where it is extremely rare.

In Britain, the storm dubbed the ‘Beast from the East’ caused London’s River Thames to freeze for the first time in decades and locked down skiers unable to fly to the Alps hiked up their local hills.

‘We’ve had everything you could possibly think of in the past week,’ said Northern Illinois University meteorologist Victor Gensini, noting that parts of the US have been 50 degrees (28 degrees Celsius) colder than normal.

‘It’s been a wild ride.’

It was warmer Tuesday in parts of Greenland, Alaska, Norway and Sweden than in Texas and Oklahoma. And somehow people in South Florida have been complaining about record warmth that is causing plants to bloom early.

In the eastern Greenland town of Tasiilaq, it’s been about 18 degrees (10 degrees Celsius) warmer than normal, which ‘is a bit of a nuisance,’ said Lars Rasmussen, a museum curator at the local cultural centre.

‘The warm weather makes dog sledding and driving on snow scooters a bit of a hassle.’

Several meteorologists squarely blamed the polar vortex breakdown or disruption.

These used to happen once every other year or so, but research shows they are now close to happening yearly, if not more, said Judah Cohen, a winter storm expert for Atmospheric Environmental Research, a commercial firm outside of Boston.

The polar vortex spends winter in its normal place until an atmospheric wave – the type that brings weather patterns here and there – slams into it. 

Normally such waves don´t do much to the strong vortex, but occasionally the wave has enough energy to push the spinning top over, and that´s when the frigid air breaks loose, Gensini said. 

Sometimes, the cold air mass splits into chunks – an event that usually is connected to big snowstorms in the U.S. East, like a few weeks ago.

Other times, it just moves to a new place, which often means bitter cold in parts of Europe. This time it did both, Cohen said.

There was a split of the vortex in early January and another in mid-January. Then at the end of January came the displacement that caused cold air to spill into Europe and much of the United States, Cohen said.

Both Cohen and Francis said this should be considered not one but three polar vortex disruptions, though some scientists lump it all together. 

While both the vortex and the wave that bumped it are natural, and polar vortex breakdowns happen naturally, there is likely an element of climate change at work, but it is not a sure thing that science agrees on, Cohen, Gensini and Francis said.

Warming in the Arctic, with shrinking sea ice, is goosing the atmospheric wave in two places, giving it more energy when it strikes the polar vortex, making it more likely to disrupt the vortex, Cohen said.

‘There is evidence that climate change can weaken the polar vortex, which allows more chances for frigid Arctic air to ooze into the Lower 48,’ said University of Georgia meteorology professor Marshall Shepherd.

There were strong polar vortex disruptions and cold outbreaks like this in the 1980s, Cohen said.

‘I think it´s historic and generational,’ Cohen said. ‘I don´t think it´s unprecedented. This Arctic outbreak has to be thought of in context. The globe is much warmer than it used to be.’

It also feels colder because just before the outbreak, much of the United States was experiencing a milder-than-normal winter, with the ground not even frozen on Christmas Day in Chicago, Gensini said.

The globe as a whole is about the same temperature as the average was from 1979 to 2000 for this time of year, according to the University of Maine’s Climate Reanalyzer. 

That´s still warmer than the 20th century average, and scientists don´t think that this month has much of a chance to be colder than the 20th century average for the globe, something that hasn´t happened since the early 1980s.

One reason is that it will soon warm back up to normal when the polar vortex returns to its regular home, Cohen said.

As for people thinking this cold outbreak disproves global warming, scientists say that´s definitely not so.

Even with climate change, ‘we’ll still have winter,’ said North Carolina state climatologist Kathie Dello. ‘What we’re seeing here is we’re pretty unprepared for almost every type of extreme weather. It’s pretty sad.’