Global warming and airflow changes 'caused US and EU heatwaves'. Air systems that encircle planet can slow to standstill, as greenhouse gas heats Arctic and causes temperature imbalance
The study of meandering air systems that encircle the planet adds to understanding of extremes that have killed thousands of people and driven up food prices in the past decade.
Such planetary airflows, which suck warm air from the tropics when they swing north and draw cold air from the Arctic when they swing south, seem to be have slowed more often in recent summers and left some regions sweltering, they said.
"During several recent extreme weather events these planetary waves almost freeze in their tracks for weeks," wrote Vladimir Petoukhov, lead author of the study at the Potsdam Institute for Climate Impact Research in Germany.
"So instead of bringing in cool air after having brought warm air in before, the heat just stays," he said in a statement of the findings in the US journal Proceedings of the National Academy of Sciences... Full Guardian story here; more on climate change issues here.