A wavy polar jet stream can bring icy storms further south
Science History Images / Alamy Stock Photo
Recent research suggests that the increasingly erratic winter weather in the northern hemisphere is not primarily caused by the polar jet stream becoming more wavy. While climate change is intensifying winter storms in other ways, the behavior of the jet stream remains relatively consistent.
The northern polar jet stream is a high-altitude wind current that flows across the northern hemisphere, influenced by the temperature differences between the Arctic region and lower latitudes.
Although some scientists have proposed that a warming Arctic is leading to more pronounced waviness in the jet stream during winter, recent studies have found it challenging to conclusively prove this theory due to limited satellite data and natural variability in the jet stream’s patterns.
Researchers, including Erich Osterberg from Dartmouth College, conducted a study using historical temperature and pressure data dating back to 1901 to analyze the jet stream’s movements over the US. Their findings indicated that the jet stream has exhibited periods of increased waviness throughout the 20th century, suggesting that the current erratic behavior is not unprecedented.
Osterberg emphasizes that while winters in the northern hemisphere are indeed experiencing changes due to climate change, the jet stream may not be the primary driver of these alterations. He notes that winter weather is becoming warmer and wetter, leading to more intense storms and precipitation events.
Tim Woollings, a researcher at the University of Oxford, underscores the importance of long-term data analysis when studying the polar jet stream, which can exhibit significant variability over different time scales. While recent winters in North America have shown increased waviness in the jet stream, this trend is not significantly different from past decades.
Interestingly, the behavior of the polar jet stream during summer months appears to be undergoing more noticeable changes linked to climate change. Osterberg points out that the jet stream is becoming slower and exhibiting larger waves in summer, contributing to phenomena such as heatwaves, droughts, and wildfires.
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