Europe’s Weather Engine is stalling: Climate Change suppresses the jet stream variability

The North Atlantic jet stream is one of the main regulators of the European climate: an intense westerly airflow that guides storms toward the continent. New evidence suggests this system is changing.

A new study published in Nature Communications Earth & Environment—conducted by researchers from the Politecnico di Torino, the University of Leeds and the University of Padua—shows that the winter variability of the jet stream is decreasing in response to emissions linked to human activities.

Using an innovative methodology developed at the University of Leeds, the research team found that jet stream fluctuations have progressively reduced over the past 80 years. While the latest generation of climate models showed a similar signal, the observed changes are on average four times stronger than in the simulations.

“Climate models agree in predicting a reduction in variability due to anthropogenic emissions, but the trend in historical reanalyses lies at the edge of the simulated trend range”, explains Andrea Vito Vacca, a PhD student at the Politecnico di Torino, who conducted the research while undertaking a research visit with Professor Amanda Maycock from the School of Earth, Environment and Sustainability.

“This indicates that the models either underestimate the atmosphere's response to greenhouse gases, or they underestimate the natural variability of the system, which could be amplifying the weakening.”

Professor Maycock said: “These new results have important implications for understanding how climate change is affecting European winter weather. A less variable jet stream could foster more persistent weather conditions, increasing the risk of extreme events”.

The study highlights how monitoring ongoing changes in atmospheric dynamics is crucial to understanding the impacts of global warming. Indeed, the emerging discrepancies between models and observations suggest that the climate system may be more sensitive than previously estimated.

Read Subseasonal variability of the winter North Atlantic jet stream has decreased due to climate change in Nature Communications Earth & Environment.