Atmospheric Waves Trapped by Emissions Caused Extreme U.S. Heat

Man-made greenhouse gas emissions trapped giant air waves in the atmosphere, causing extreme weather events such as a heat wave in the U.S. in 2011 and floods in Pakistan in 2010, researchers in Germany said.

The waves usually ship warm and cold air from the Tropics and Arctic to places such as Europe, Russia or the U.S, according to an article to be published this week in Proceedings of the National Academy of Sciences. Man-made climate change repeatedly disturbs the waves’ patterns and can trap them, the scientists at the Potsdam Institute for Climate Impact Research found.

“During several recent extreme weather events these planetary waves almost freeze in their tracks for weeks,” Vladimir Petoukhov, the study’s lead author, said in an e-mailed statement. “So instead of bringing in cool air after having brought warm air in before, the heat just stays.”

Climate change has moved up the U.S. political agenda in the wake of Hurricane Sandy. President Barack Obama presented climate change as a priority for his second term during his Feb. 12 State of the Union address, saying that heat waves, droughts, wildfires and floods “are now more frequent and intense.”

Scientists at the Potsdam Institute found that the waves get trapped because global warming disrupts the temperature differences, a driver of air flow, between locations such as the Arctic, which warms more, and Europe, which warms less.

“Our dynamical analysis helps to explain the increasing number of novel weather extremes,” said Hans Joachim Schellnhuber, a co-author of the study. “It complements previous research that already linked such phenomena to climate change, but did not yet identify a mechanism behind it.”

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