By Stephen Leahy
UXBRIDGE, Canada, Feb 27 2013 (IPS)
Scientists in Germany say they have found how greenhouse gases from burning fossil fuels are helping to trap the jet stream, resulting in extraordinary weather such as the 2010 Pakistan flood and the 2011 heat wave in the United States.
Human-driven climate change repeatedly disturbs the flow of atmospheric waves around the globe’s Northern hemisphere, said lead author Vladimir Petoukhov of the Potsdam Institute for Climate Impact Research (PIK) in Germany.
Giant atmospheric waves called Rossby waves are meanders in the strong, high-altitude winds known as jet streams and have a major influence on weather. These wave movements are caused by the difference in temperatures between the cold air from the Arctic and hot air from the tropics.
When the waves shift north, they suck warm air from the tropics to Europe, Russia, or the U.S., and when they swing down, they do the same thing with cold air from the Arctic, said Petoukhov.
“During several recent extreme weather events, these planetary waves almost freeze in their tracks for weeks,” he said. “So instead of bringing in cool air after having brought warm air in before, the heat just stays.”