Contrary to previous belief – researchers found that the jet stream’s recent “waviness”, its dramatic meanders that bring Arctic air southward—is not unprecedented and may not be directly linked to global warming.
The study, published in AGU Advances, analysed 125 years of wintertime jet stream variability using long-term climate records and machine learning, offering the first comprehensive dataset dating back to 1901.
Previous research largely focused on the satellite era, beginning in 1979.
“The jet stream was frequently just as wavy as it is today, if not more so, before climate change would have been a significant influence,” said lead author Jacob Chalif.
“This calls into question whether climate change is causing the jet stream to be more erratic now.”
Associate professor and senior author Erich Osterberg added: “Our research shows that the jet stream isn’t doing anything unusual that would cause the recent increase in intense storms.
Climate change is intensifying these storms through a different process.”
The research suggests that previous studies may have misinterpreted natural jet stream variability as a climate-driven trend due to the short observational window.
For example, a particularly wavy period in the 1960s–80s coincided with the “warming hole”—a regional cold anomaly in the southeastern US—demonstrating that such fluctuations have long existed.
While the study repositions the jet stream’s role in current climate models, it reinforces the urgency to address global warming.
“We must rapidly reduce the production of new greenhouse gas emissions worldwide,” said Osterberg, “but we must also identify the correct mechanisms driving extreme weather to inform better solutions.”
The findings highlight the importance of robust historical data to avoid oversimplifying complex climate systems.
