The shifting jet stream has magnified wildfires and plagues. What’s next?

When the bubonic plague hit England in the summer of 1348 – believed to be spread by fleas, lice, or infected humans – it found a fertile ground for disease to spread. London’s unsanitary conditions, coupled with overcrowded homes, made it difficult for the immune systems of its residents to fight off the new strains of plague circulating through Europe. The jet stream, a band of winds high in the atmosphere, had shifted drastically northward at the time, bringing cool, damp summers that kept people indoors, where diseases spread easily. By 1350, the Black Death had claimed the lives of a third of England’s population. Recent research published in the journal Nature suggests that the jet stream’s movements can exacerbate epidemics, impact crop harvests, and fuel wildfires. Despite the complexities of its behavior, understanding how the jet stream operated in the past can provide vital insights into how it may be changing due to climate change. Analyzing tree ring data spanning 700 years, researchers were able to reconstruct the jet stream’s historical patterns and their impact on epidemics, crop yields, and wildfires. The study found correlations between extreme positions of the jet stream and their effects on the ground. These findings underscore the importance of studying ancient climate patterns to predict future climate change impacts accurately.