What surprised the scientists was that the jet stream’s meandering has become more frequent. “Since 1960 we get more years when the jet is in an extreme position,” Trouet says, either in its northernmost or southernmost position. She adds that this pattern of more frequent, extreme shifts north and south has never been seen before in her 290-year record.
Writing in the journal Nature Communications, the researchers say these more dramatic fluctuations may be responsible for some recent extreme weather events, not just in Europe, but also North America.
“Heat waves, droughts and floods affect people,” says Trouet. These “happen on top of already increasing temperatures and global warming — it’s a double whammy.”