20
Tue, Feb

Jet Stream Changes Since 1960s Linked to More Extreme Weather

Typography

Increased fluctuations in the path of the North Atlantic jet stream since the 1960s coincide with more extreme weather events in Europe such as heat waves, droughts, wildfires and flooding, reports a University of Arizona-led team.

The research is the first reconstruction of historical changes in the North Atlantic jet stream prior to the 20th century. By studying tree rings from trees in the British Isles and the northeastern Mediterranean, the team teased out those regions' late-summer weather going back almost 300 years — to 1725.

Increased fluctuations in the path of the North Atlantic jet stream since the 1960s coincide with more extreme weather events in Europe such as heat waves, droughts, wildfires and flooding, reports a University of Arizona-led team.

The research is the first reconstruction of historical changes in the North Atlantic jet stream prior to the 20th century. By studying tree rings from trees in the British Isles and the northeastern Mediterranean, the team teased out those regions' late-summer weather going back almost 300 years — to 1725.

"We find that the position of the North Atlantic jet in summer has been a strong driver of climate extremes in Europe for the last 300 years," said Valerie Trouet, an associate professor of dendrochronology at the UA Laboratory of Tree-Ring Research

Having a 290-year record of the position of the jet stream let Trouet and her colleagues determine that swings between northern and southern positions of the jet became more frequent in the second half of the 20th century, she said.

"Since 1960 we get more years when the jet is in an extreme position," Trouet said, adding that the increase is unprecedented. 

Read more at University of Arizona

Photo: Valerie Trouet takes a pencil-thin core from an old Bosnian pine (Pinus heldreichii) growing on Mount Olympus in Greece. (Photo Credit: Greg King © 2010)