Man-made climate changes may be behind extreme weather patterns that ravage the world such as the US and Russian heat waves in 2011 and 2010 and the unprecedented floods in Pakistan.
Potsdam Institute for Climate Impact Research (PIK) scientists from Germany have revealed how man-made climate change upsets the patterns of atmospheric flow around the Northern Hemisphere.
“An important part of the global air motion in the mid-latitudes of the Earth normally takes the form of waves wandering around the planet, oscillating between the tropical and the Arctic regions,” says Vladimir Petoukhov of PIK, who led the study, the journal Proceedings of the National Academy of Sciences reports.
“So when they swing up, these waves suck warm air from the tropics to Europe, Russia, or the US, and when they swing down, they do the same thing with cold air from the Arctic,” explains lead author Vladimir Petoukhov, according to a PIK statement.
“What we found is that during several recent extreme weather events these planetary waves almost freeze in their tracks for weeks. So instead of bringing in cool air after having brought warm air in before, the heat just stays. In fact, we observe a strong amplification of the usually weak, slowly moving component of these waves,” says Petoukhov.
Time is critical here: two or three days of 30 degrees Celsius are no problem, but 20 or more days lead to extreme heat stress. Since many ecosystems and cities are not adapted to this, prolonged hot periods can result in a high death toll, forest fires, and dramatic harvest losses.
Climate change caused by emissions from fossil-fuel burning does not mean uniform global warming in the Arctic, the relative increase of temperatures, amplified by the loss of snow and ice, is higher than on average.