Jet Stream’s Centuries-Long Impact on European Societies Revealed

The jet stream is a band of strong winds that encircles the Earth at high altitudes. Changes in the jet stream significantly influenced summer weather in Europe centuries ago, sometimes with serious social consequences. This finding comes from an international team of researchers, including a scientist from the University of Freiburg, in their recent study published in the journal Nature.

Direct measurements of the jet stream have only been available since the late 1940s. To overcome this limitation, the team analyzed tree rings from samples taken in three European regions (the British Isles, Alps, and Balkans) to reconstruct historical changes in the jet stream as far back as 1300 AD. Using this data, the researchers showed that for over 700 years, the jet stream has been generating contrasting summer weather between northwestern and southeastern Europe. The study also demonstrates that these weather patterns had major social impacts, as they contributed to harvest failures, wildfires, and epidemics.

“Our study demonstrates the jet stream’s significant impact on European agricultural production throughout history ” explains Dr. Andrea Seim from the Faculty of Environment and Natural Resources, a co-author of the study. “When the jet stream shifted abnormally northward, it led to cold, wet weather in northwestern Europe and hot, dry conditions in southeastern Europe. This often resulted in crop failures, rising grain prices, and threats to food security.” Dr. Seim, who will assume the Interim Professorship for Forest History at the University of Freiburg on October 1st, highlights the study’s key finding: “We’ve shown that summer weather extremes caused by unusual jet stream positions had profound effects on historical societies.” The researchers emphasize that these findings have implications for the future. They suggest that climate change could significantly alter the jet stream, potentially leading to more frequent and severe extreme weather events.