A Stagnant Jet Stream Is Fueling Intense Heat Worldwide. Could Climate Change Be to Blame?

A stagnant polar jet stream is currently trapping heat over parts of North America, Europe, and Asia. UK Met Office
A stagnant polar jet stream is currently trapping heat over parts of North America, Europe, and Asia. UK Met Office

The jet stream, the narrow band of westerly winds circling the northern hemisphere, is stagnating, giving rise to severe heat across much of the globe, and climate change may be making it worse, a new study finds.

“The jet stream is currently in a stationary position, which means that weather systems are kept in a holding pattern that makes heat build up in some regions of the world, such as southern Europe, southern North America, and Eastern China,” said Liz Stephens, a climate scientist of the University of Reading, who was not affiliated with the new research.

Scientists have long posited that rising temperatures may be weakening the jet stream, which is formed by the collision of cold, Arctic air with warm, southerly air. With climate change, the Arctic is warming faster than the lower latitudes, narrowing the difference in temperature. As a result, the jet stream may be growing slower and wavier, allowing warm air from the tropics to flow north and become trapped over Europe, Asia, and North America, fueling severe heat and intense wildfires.

The new study finds evidence that rising temperatures in the Arctic are, in fact, distorting the jet stream. Examining weather data from 1979 to 2022, researchers found that as snow cover in northern Canada declined, the jet stream grew wavier, allowing warm air to settle over Greenland, hastening ice melt. The findings were published in the journal Nature Communications.

“That’s the question behind a lot of emerging climate research, whether we are going to expect to see more persistent weather extremes,” said Jonathon Preece, a postdoctoral researcher at the University of Georgia and lead author of the study. “These persistent and extreme conditions are thought to be increasing in the future as a result of this increased waviness in the jet stream.”

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