The patterns of Earth’s high winds have surprisingly widespread effects on life on the ground. A recent study in the journal Nature shows that when the summer jet stream over Europe veers north or south of its usual path, it brings weather extremes that can exacerbate epidemics, ruin crop harvests, and feed wildfires.

“The jet stream has caused these extreme conditions for 700 years in the past without greenhouse gases,” said Ellie Broadman, a co-author of the study and a researcher at the University of Arizona. “To me, that’s a little scary, to think about the compound effects of simply adding more heat to the atmosphere and imagining how those extremes might get more extreme in the future.”