Recent studies indicate that the increasingly erratic winter weather in the Northern Hemisphere is not solely due to more pronounced wavy polar jet streams.

The Arctic jet stream functions as a wind current that helps to maintain the balance between temperate and cold air in the Arctic region.

For over a decade, some researchers have engaged in discussions regarding the effects of the warm Arctic on the jet stream. This warming has reportedly intensified in winter, leading to severe storms that carry snow and ice much further south than usual.
However, doubts persist about this theory.

Testing this hypothesis has proven challenging due to limited satellite data and the natural fluctuations of the jet stream during winter.

Researchers like Erich Osterberg from Dartmouth University have sought to determine whether the recent behavior of the jet stream deviates from the long-term average.

Since satellite observations of the jet stream began only in 1979, researchers leveraged temperature and atmospheric pressure data extending back to 1901 to reconstruct the movement of polar jets across the United States throughout the 20th century.

They discovered that polar jets exhibited wave-like patterns during various periods, indicating that the current erratic behavior may not be unprecedented. In fact, at times, the winter jet stream was even more undulating than it is today. “What we’re observing with the jet stream now is not particularly unusual when you consider the broader context of the 20th century,” Osterberg states.

The winters in the Northern Hemisphere are becoming warmer and wetter, a trend emphasized by Osterberg even as climate change continues to provoke more severe storms and precipitation. “It’s evident that climate change is influencing extreme weather events significantly,” he remarks. “However, in the context of winter jet streams, these changes don’t appear to be a fundamental factor.”

Similarly, Tim Woolling from Oxford University highlights the importance of long-term data in identifying shifts in polar jet stream behavior, noting its significant variability in the short to medium term. “Utilizing extensive data records and diverse methodologies reveals that today’s North American winter jet patterns are not necessarily worse than in previous decades,” he explains.

Contrastingly, during the Northern Hemisphere summer, emerging evidence suggests that climate change has elevated tropical temperatures, leading to broader polar waves in warmer months. “In summer, it seems that the jet stream undergoes a fundamental shift in behavior, with larger waves leading to intense heat waves, droughts, and wildfires,” Osterberg adds. “This phenomenon appears to be linked to climate change.”