Warmer Arctic summers may be bringing colder winters to the UK, new research suggests.
The globe is getting warmer and this will favour warmer temperatures
Global warming in northern polar regions could be having a surprising knock-on effect further south, scientists believe.
High pressure in the Arctic is thought to push colder air into mid-latitude regions, producing chillier winters.
It could explain a trend of increasingly harsh winters in North America and Europe over the past two decades.
Last winter was the coldest for 31 years in the UK with an average December to February temperature of 1.51˚C. It also saw the coldest December since records began.
Meanwhile on the other side of the Atlantic people braced themselves against abnormally cold conditions for the second year in a row.
The US has experienced the harshest two successive winters for around a quarter of a century.
Cold snaps can occur for a multitude of reasons to do with natural climate variability. But the scientists believe they can see a trend linked to increased autumn snow over northern Europe and Asia.
The findings were published in the journal Environmental Research Letters.
Lead scientist Dr Judah Cohen, from US-based climate consultants Atmospheric and Environmental Research Inc, said: “In my mind there is no doubt that the globe is getting warmer and this will favour warmer temperatures in all seasons and in all locations; however, I do think that the increasing trend in snow cover has led to regional cooling as discussed in the paper and I see no reason why this won’t continue into the near future.”
According to the theory, warmer conditions combined with melting sea ice allow the Arctic atmosphere to hold more moisture. This in turn increases the likelihood of precipitation – most probably snow – across more southerly regions.
The increased snow cover has an impact on the Arctic Oscillation, a pressure pattern that affects climate in mid-to-high latitudes. Due to a “negative phase” Arctic Oscillation, raised atmospheric pressure over the Arctic pushes colder air into mid-latitude regions, sending winter temperatures down. Understanding the connection with Eurasian snow cover could improve the accuracy of seasonal weather forecasts, claim the scientists.
“Without correctly simulating the coupling of winter climate patterns and the variability of snow fall, the models currently used by government centres miss an important influence on winter and will therefore continue to be deficient in predicting winter weather on seasonal time scales, and even longer decadal time scales,” said Dr Cohen.