us heatwave
A man rests during a heat wave in Manhattan, New York, July 19, 2013. reuters/Eduardo Munoz

A rapid rise in temperature in the Arctic region over the last two decades could be responsible for extreme weather events throughout the northern hemisphere, scientists from the Potsdam Institute for Climate Impact Research in Germany said in a study published Monday. Both U.S. and Europe have seen cold snaps, heat waves and flooding in recent years.

“The large number of recent high-impact extreme weather events has struck and puzzled us,” Dim Coumou, lead author of the study published in the journal Proceedings of the National Academy of Sciences, said in a press release. “Of course we are warming our atmosphere by emitting CO2 from fossil fuels, but the increase in devastating heat waves in regions like Europe or the US seems disproportionate.”

The U.S. had, in 2011, witnessed average summer temperatures of 74.5 degrees Fahrenheit, making it the hottest summer on record since 1936. The paper also studied the 2010 heat wave in Russia and floods in Pakistan, a 2003 heat wave in Europe, and rains that caused flooding of the Elbe and Danube Rivers in Europe in 2002.

The scientists analyzed large sets of global weather data and concluded that wind patterns called “Rossby waves” were responsible for the anomalous weather.

Researchers said that the loss of sea ice in the Arctic, and a subsequent increase in surface temperatures, were causing wide fluctuations, called Rossby waves, in the high-altitude winds flowing around the polar region. This was causing them to “become virtually stalled and greatly amplified” in low-lying areas, the paper said.

When this high-altitude wave swung north, it swept warm air from the tropics over Europe, Russia or North America, and when it swung south it sucked in cold air from the Arctic, resulting in long-lasting weather patterns and causing extreme heat, cold, drought or flood, the researchers claimed.

The study found a correlation between the frequency and strength of such stalled waves and the increase in the Arctic surface temperature.

The paper said that since 2000, the Arctic has been heating up about twice as fast as the rest of the world, which is causing a decline in the temperature difference between the North Pole and the rest of the world, resulting in widespread “perturbations” in the atmospheric circulation patterns.

The study also found that the number of extreme weather events, such as heat waves, floods and droughts, had almost doubled over the same period.

“This illustrates how delicately interlinked components in the Earth system are,” study co-author Hans Joachim Schellnhuber said.