Arctic melt may cause soggy summers
Melting Arctic sea ice may be to blame for the recent spate of soggy summers in the UK, say experts.
Loss of ice due to climate change is affecting strong air currents high in the atmosphere, research suggests.
As a result, weather systems are being shifted bringing more summer rain to the UK and other parts of north-west Europe.
Scientists at the University of Exeter used a computer model to simulate the effects of retreating Arctic sea ice on European climate.
The model produced a pattern of rainfall consistent with an extraordinary run of washed-out summers experienced in the UK between 2007 and 2012.
Lead researcher Dr James Screen said: "The results of the computer model suggest that melting Arctic sea ice causes a change in the position of the jet stream and this could help to explain the recent wet summers we have seen.
"The study suggests that loss of sea ice not only has an effect on the environment and wildlife of the Arctic region but has far-reaching consequences for people living in Europe and beyond."
Jet streams are powerful 200mph air currents high in the atmosphere that steer weather systems.
Normally in summer, the polar jet stream flowing between Scotland and Iceland keeps bad weather north of the UK. When the jet stream shifts south, it brings unseasonable wet weather with it.
Arctic sea ice is retreating at a rate of around half a million square kilometres per decade - about twice the area of the UK.
The study, published in the journal Environmental Research Letters, compared weather patterns associated with low levels of Arctic sea ice and the high sea ice conditions seen in the late 1970s.
It showed that while melting sea ice led to more summer rain in north-west Europe, Mediterranean regions were likely to get drier.
Further ice loss could increase the risk of wet summers in the UK, say the scientists, although they make no prediction of future sea ice levels.
In their paper, the researchers point out that the series of wet summers that doused north west Europe between 2007 and 2012 was "unprecedented".
For England and Wales, the summer of 2012 was the wettest and the summer of 2007 the second wettest since 1912.
The model showed that while the effect of low Arctic sea ice was significant, its influence could be cancelled out by other factors.
Precisely how melting Arctic sea ice affects the jet stream is unclear, say the scientists.
One study suggested a connection between reduced snow cover and sea ice, ridges of high atmospheric pressure over Greenland, and a southward meander in the jet stream.