Change in jet stream behind Storm Eunice may be indicator of climate crisis

22 Feb 2022

Image: © Marina Gordejeva/Stock.adobe.com

The jet stream has moved 330km northwards and increased in speed between 1871 and 2011, a new Irish-led study has found.

A new study has found that the North Atlantic and Eurasia jet stream that brought storms Dudley, Eunice and Franklin to Ireland and the UK in recent days has been moving northwards and increasing in speed over the past century, influencing storm activity.

Jet streams are fast bands of air that flow around the globe at around 10km above the Earth’s surface.

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Led by Maynooth University researcher Dr Samantha Hallam, the study analysed jet stream patterns over a 141-year period between 1871 and 2011. It found that the North Atlantic and Eurasia jet stream has moved northwards by approximately 330km and the mean winter jet speed has increased 8pc to 212kph.

This has had a considerable influence over storm activity and temperature patterns in the North Atlantic, increasing the likelihood of strong winds and flooding events. However, the same trend has not been observed in the North Pacific.

The study found that jet stream trends vary on a regional and seasonal basis, and said that the trends observed over time are potential indicators of the climate crisis.

Headshot of Dr Samantha Hallam smiling at the camera.

Dr Samantha Hallam. Image: Maynooth University

Hallam, who is lead author of the study, said that the significant increases in winter jet stream latitude and speed observed over the North Atlantic and Eurasia regions are consistent with the decreasing temperature and increasing pressure gradients observed between the equator and the Arctic over the period.

“Over the North Pacific, no increase in jet latitude or speed are observed. However, changes in the North Pacific sea surface temperatures explains over 50pc of the variability in jet latitude,” she said.

“The results highlight that Northern Hemisphere jet variability and trends differ on a regional basis. This is important for making climate predictions and in developing plans to combat climate change.”

The study was published in the scientific journal Climate Dynamics this week.

A collaboration between the ICARUS climate research centre at Maynooth University, the University of Southampton and the UK’s National Oceanographic Centre, the study was supported by the Marine Institute and funded by the Irish Government.

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Vish Gain is a journalist with Silicon Republic

editorial@siliconrepublic.com