Why was the UK suddenly covered in heavy snow?
The blast of cold air sweeping in from Siberia to Western Europe, popularly dubbed as ‘beast from east’, is a result of a break down in jet streams over Scandinavia.
Jet streams are basically ribbons of strong, high altitude winds (upto 200mph), blowing across Atlantic west to east, that are responsible for the shifts in weather across the globe.
Jet streams naturally move either in a “wavy” irregular path or in strong-steady flow. And previous studies have shown the weather to be much cold moving south from the Artic towards the mid-latitudes, even bringing freezing temperatures when the jet streams move in a wavy path. Whereas, when jets streams move strong and steadily from west to east, winter weather conditions are milder in the countries that lie between the tropics and the Artic, including the UK.
And although there is no denying that last week’s bad winter weather has been a result of a natural shift, scientists are now linking the increasing frequencies of such weather shifts and anomalies to a larger change in global weather.
(Check out this video by Met Office on jet streams)
What is causing these weather anomalies across the globe?
While rest of the world is suffering from dropping degrees, scientists say temperatures have risen above freezing repeatedly at the North Pole, reaching as high as 30C above normal for the depths of winter.
Such a radical difference (rise) in temperature in Arctic, especially in winter seasons, evidently does not bode well for the rest of the world. And the fact that these changes are in-part largely a result of man-made climate changes, makes things even more critical.
Professor Edward Hanna, of the University of Sheffield, said: “We’ve always had years with wavy and not so wavy jet stream winds, but in the last one to two decades the warming Arctic could well have been amplifying the effects of the wavy patterns.
“This may have contributed to some recent extreme cold winter spells along the eastern seaboard of the United States, in eastern Asia, and at times over the UK.”
(Read more about his research on Extreme cold winters fuelled by jet stream and climate change here.)
The lead scientist at Berkerley Earth, Robert Rohde, too pointed out recently that the North Pole is warmer than much of Europe.
And this anomaly is due to the dark retreat of sea ice in Arctic winter, resulting in temperatures above the freezing level at the meteorological site in the northern extreme of Greenland for a record-breaking 61 hours, so far in year 2018. As shown by the graph (below) from Robert Rohde’s research.
But the bigger question that comes to mind is that what is the probability of such weather conditions repeating itself? They are possibly higher than what would have been few decades ago. Especially with recent studies showing an increase in frequency of warm air intrusions, making scientists believe that the further reduction in ice sea on the Arctic Ocean will allow warmer water to release heat into the atmosphere, resulting in knock-on effects for the jet stream.
The most worrisome thing is not what is happening right now to the weather but how often this has started happening in the recent years.
This video by the Robert Rohde and the Berkerley Earth division showing how climate has changed in 168 years.
Cars and street covered with heavy snow in Central London. As the snow and cold grew, many motorways were forced to close down due to high levels of invisibility and accidents. Trains were delayed when not altogether cancelled. Even the airways suffered, with British Airways cancelling many flights from Heathrow Airport, London.