How Britain’s cold snap is caused by warm air elsewhere

By Ed McCue on 05/03/18 

The ‘Beast from the East’ has gripped headlines in recent days because of the harsh wintry conditions that have clinched The UK and the rest of Europe. Freezing conditions have swept across Europe, as temperatures plummeted to as low as -30°C.


Manchester has experienced heavy snowfall and temperatures falling to as low as -7°C, in what has been described as the ‘worst winter weather in decades’. Last Thursday morning, a huge 16 vehicle pile-up caused the M66 to be closed in both directions, wounding 20 people. The Metrolink was also disrupted by the conditions, as trams from Bury to Manchester and Rochdale via Oldham were suspended. Storm Emma then brought gale force winds to the regions, with gusts recorded of up to 77mph. But the current climatic conditions in the northernmost section of the planet should overshadow the wintry setting that Europe finds itself in.


The Arctic has been unusually warm since the beginning of 2018. Despite the North Pole being covered in darkness for another month, the Arctic has been as much as 35°C hotter than average in some areas. In mid-winter, when sea ice should be growing, in the Bering Sea its instead shrinking.


From this, Arctic Ocean sea ice is at a record low for late February, at 14.1 million square kilometres – about a million square kilometres less than normal (that’s roughly the size of Egypt).


For two days in February, the North pole has been warmer that Zurich. At one spot in Greenland, the temperature rose 36°C above the annual average. The country itself has already experienced 61 hours above freezing in 2018 – more than three time as many hours in any previous years. It is no wonder that it has never been so warm for so long at this time in the Arctic.


Paradoxically, the Arctic warming and chill in Europe are directly linked.  The World Meteorological Organisation says that the chill in the UK and the rest of Europe has been caused by the Arctic warming (known as ‘sudden stratospheric warming’) above the North Pole, that has led to a split in the polar vortex (a band of ring-like strong winds containing cold polar air).


The sudden stratospheric warming has played a huge role in determining our current weather. It weakens the jet stream that brings warm air to Britain in from the Atlantic. Consequently, this allows cold air from western Russia to infiltrate Europe.


The polar vortex is driven by the temperature differences between the warm mid-latitudes and the cold Arctic. Because the Arctic is warming at a more rapid rate compared to the mid-latitudes (because of global warming), this temperature difference is falling, weakening the polar vortex.


Research suggests that this weakening will cause more frequent outbursts of cold, polar air at low latitudes and cause warmer air to flood the Arctic.


Subsequently, this would only increase the loss of sea ice and accelerate the global warming process, as an unwanted cycle or ‘positive feedback loop’ arises. For example, stratospheric warming may arise due to increased levels of greenhouse gases in the atmosphere. This then weakens the polar vortex because of increased temperature difference between differing latitudes. The weakened polar vortex then increases the amount of warm air in polar regions and ice caps begin to melt at an even quicker rate, releasing trapped greenhouse gases in the process, until, eventually, the cycle repeats.


But what causes stratospheric warming in the first place? Although it could yet prove to be a freak event, the primary concern is that global warming is eroding and weakening the polar vortex. However, when linking such events to climate change, it is important to address it with caution. One extreme event doesn’t accurately represent the longer-term changes of the Arctic and European climate.


Furthermore, the melting sea ice on the Arctic Ocean, due to global warming, exposes the warmer water below, releasing more heat into the atmosphere and disrupting the high-altitude jet stream, increasing the likelihood of cold air reaching further south and warm air further north.


Spikes in temperature in the Arctic region are part of normal weather patterns, but the heat peaks are becoming more frequent and lasting longer. “In 50 years of Arctic reconstructions, the current warming event is both the most intense and one of the longest-lived warming events ever observed during winter,” said Robert Rohde, lead scientist of Berkeley Earth, a non-profit organisation dedicated to climate science.


Head of UN Environment, Erik Solheim, says that the rare weather system fits a wider pattern ‘driven by a build-up of greenhouse gases, mainly from burning fossil fuels from cars, factories and power plants.’


The sudden stratospheric warming in the Arctic seem isolated and distant – it seems hard to believe its effects are already beginning to be felt so close to home. Climate change may be a factor in driving more extreme Arctic warming, which in turn has caused the UK’s cold snap that we are currently experiencing. We could be feeling the full force of global warming, ironically, in the form of freezing conditions, and we don’t even realise.