The past couple of days I’ve been keeping an eye on events back home by checking UK news feeds and messaging friends. It seems things really have got interesting, with a easterly Siberian cold air mass, nicknamed ‘The Beast From The East’ clashing with a storm coming in from the west, given the name ‘Emma’ by the Portuguese Meteorological Service.
While the ‘Beast From The East’ had already caused problems for the British Isles, when ‘Emma’ joined in the fun, the south-west of England were issued with red warnings by the MetOffice, meaning there is a danger to life, among other threats.
When it comes to case studies, knowing the exact dates is not only useful but pretty vital for doing lesson or resource preparation, or enabling students to conduct their own research:
So while I thought about doing a classic ‘case-study’ style blog entry about the current extreme weather hitting the British Isles right now, looking at the impacts and responses etc, I quickly found that focusing on the causes alone revealed some interesting, surprising and perhaps concerning elements that are not so obvious. So I’ll leave the Geography teaching community to rustle up the classic case-study (a good example on the left!) I’m going all-in with the causes…
Clearly this is an extreme cold weather event. And talking about very cold winds (the ‘Beast’) originating from Russia in the east offers a relatively simple explanation to it being rather cold!
So Emma comes along carrying moisture picked up from over the Atlantic Ocean. This collides with the cold air mass coming from the east, causing more snow to be dumped over the UK.
And so chaotic scenes ensue, including my school among many others having to be shut for the whole week, and in Diss, Norfolk – where I hope my house and its tenants are coping with the conditions without any issues! (Bracing myself for the estate agents to get in contact with bad news…)
But really, it’s all hot air…
However, the reason why we have a blast of very cold air coming from the east is counter-intuitive. It’s because we have too much warmth both in and above the Arctic. First, let’s start with the temperature readings that stunned scientists keeping tabs on the Arctic:
In fact, on the 21st February, some areas of the Arctic had recorded temperatures 30°C/54°F higher than their 1979-2000 average. This shocked scientists and got plenty of media attention, like this article in the Washington Post.
But it’s not just this sudden pulse of warm temperatures in mid-to-late February which has caught the attention of a lot of scientists and organisations, its that these conditions are becoming warmer and more persistent during the Arctic winter. The three months of December 2017, January and February 2018 saw the Arctic 7ºC warmer than the 1981-2000 average.
So what has this got to do with the cold ‘Beast From The East’, then? Well in fact, the MetOffice having noted the exceptionally warm temperatures over the Arctic, a couple of weeks ago predicted that a cold snap with potential heavy snowfall was to follow. The warming Arctic is causing ‘normal’ weather patterns to be disrupted.
A polar vortex is a circulation of very strong winds in the high in the atmosphere. One circles west-to-east around Antarctica, and the other circles west-to-east around the Arctic. Alex Deakin from the MetOffice, who Brits may recognise from TV weather forecasts, gives a really good explanation of the polar vortex, and how changes in it can affect the weather over the UK:
What is generally the case, is that when there is less of a temperature difference between the Arctic and places further south, then the polar vortex weakens and wobbles. Since this winter the Arctic has been exceptionally warm, the vortex has not just weakened, it seems to have even splintered and fragmented. Jeremy Mathis of NOAA uses the analogy of the Arctic being the planet’s refrigerator. He says that when the vortex is weak, it’s like…
“…the door to that refrigerator has been left open… And the cold is spilling out, cascading throughout the northern hemisphere.”
The weakening of the polar vortex, and in turn the jet-stream has meant that colder air has allowed to spill out from the Arctic, driving temperatures down in some places further south.
The graphic on the left shows temperatures about a kilometer up in the air from 28th February, giving the appearance of the cold air is spilling out of the Arctic.
This extreme weather event is one example why the term ‘global warming’ is so confusing. For a start, you cannot associate a single event to it, but the confusion comes from people thinking it means everywhere on the planet will be much warmer all the time. But what it actually means is that the average temperature of the planet increases, which in turn causes weather processes and climate patterns to change. Hence the more used term of ‘climate change’. I suppose ‘global weirding’; would work too, given that it all really is, well, weird! This extreme weather event is also yet another example of why some confuse weather and climate.
Jonathan Watts of The Guardian has done a good Q&A which you should check out, exploring the potential relationship between these cold snaps and climate change. Also good further reading can be found by the BBC, and The Conversation.
So to twist the words of a certain world leader’s tweet: Perhaps we could use a little less of that good old Global Warming… Bundle up! (Yes.. things are weird at the moment!)
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