The extreme cold snap that left millions of people in Texas without power last winter appears to have been made more likely by melting Arctic sea ice thousands of kilometres away, research suggests.
For the past decade, evidence has been building in support of the counterintuitive idea that some of the recent cold winter spells at mid-latitudes in North America and Eurasia are linked to the Arctic warming faster than the rest of the world due to climate change.
That link still isn’t fully established. However, a group led by Judah Cohen at the Massachusetts Institute of Technology found that vanishing sea ice and greater snowfall in the Arctic over the past 40 years, effects caused by climate change, may be driving cold winter weather in North America and Eurasia via the stratospheric polar vortex, the cold winds high above the pole. The rapid warming in the Arctic appears to be disrupting – that is, stretching – this vortex in a way that has a knock-on effect on atmospheric circulations above North America, generating unusually cold spells in winter.
“If you expected global warming to help you out with preparing for severe winter weather, our paper says the cautionary tale is: don’t necessarily expect climate change to solve that problem for you,” says Cohen. “This is an unexpected impact from climate change that we didn’t appreciate 20 years ago.”
The researchers arrived at their findings using modelling of Arctic snow and sea ice, as well as observations snow and sea ice from October 1980 to February 2021. They also used data on the polar vortex and temperature data for North America. Cohen and his colleagues say their analysis suggests that the cold that hit Texas in February was likely a response to disruption in the stratospheric polar vortex in the same month. “I think it made it more likely,” he says.
Jennifer Francis at the Woods Hole Oceanographic Institution in Falmouth, Massachusetts, says: “By analysing both observations and model simulations, the conclusions are well supported and help explain how extreme cold spells like the debilitating one in Texas this past February are still likely – and perhaps more so – as the climate crisis unfolds.”
Journal reference: Science, DOI: 10.1126/science.abi9167
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