Despite suggestions to the contrary, rapid Arctic warming has not led to a “wavier” jet stream around Earth’s mid-latitudes, new research suggests.
In fact, say scientists from the University of Exeter, UK, in a paper in the journal Science Advances, it is likely the other way around.
Random fluctuations in the jet stream are influencing Arctic temperatures.
“While there does appear to be a link between a wavier jet stream and Arctic warming in year-to-year and decade-to-decade variability, there has not been a long-term increase in waviness in response to the rapidly warming Arctic,” says co-author Russell Blackport.
For two decades, scientists have observed the jet stream – a powerful band of westerly winds across the mid-latitudes – getting a “wavier” flow, coinciding with greater Arctic warming through climate change.
These waves have caused extreme weather conditions to strike mainland Europe and the US, bringing intense cold air that leads to extreme cold weather.
In their study, Blackport and colleague James Screen studied climate model simulations and observed conditions going back 40 years.
They found that the previously reported trend toward a wavier circulation during autumn and winter has reversed in recent years, despite continued Arctic amplification.
This reversal has resulted in no long-term trends in waviness, in agreement with climate model simulations, which also suggest little change in “waviness” in response to strong Arctic warming.
“The well-publicised idea that Arctic warming is leading to a wavier jet stream just does not hold up to scrutiny,” says Screen.
“With the benefit of ten more years of data and model experiments, we find no evidence of long-term changes in waviness despite on-going Arctic warming.”
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