Amy Goodman speaks with Paul Epstein about how global warming contributes to extreme weather events.
DR. PAUL EPSTEIN: Good morning, Amy. Good to be with you.
Yes, we are certainly in a spate of extreme weather events, and it seems that this year has been a real uptick in all sorts of events, from heavy rains to droughts to heat waves and now cold weather. And I think if we think back at last winter, we also had a very intense winter with three large snowstorms together. And now we’re seeing this heavy snowfall in the United States, but also the last several months in Europe, as you recall here.
The underlying issue between global warming and climate change, meaning warming and changes in weather patterns, is that in the last 50 years, the oceans have absorbed 22 times as much heat as has the atmosphere. Let me repeat that, because it’s not often considered as part of the global warming story, but the heat of the last half century has built up in the oceans, and it’s the accelerated evaporation off of warm oceans that drives the heavy rains. A warmer atmosphere also holds more water vapor. For each one degree centigrade it heats up, it holds seven more—seven percent more water vapor.
From Time Magazine
The loss of Arctic sea ice helps accelerate the warming of the atmosphere in the far north, thanks to what’s known as the albedo effect. White ice reflects sunlight into space, cooling the air, but when ice melts and is replaced with dark ocean water, the effect is reversed and more of the sun’s heat is absorbed. As the Arctic air warms, it raises the altitude of discrete areas of high pressure, which can then alter wind patterns. This, in turn, can weaken the jet stream, allowing more cold air to seep out of the Arctic and into Europe and the eastern U.S. As the authors of the National Oceanic and Atmospheric Administration’s recent “Arctic Report Card” put it, “There is evidence that the effect of higher air temperatures in the lower Arctic atmosphere in fall is contributing to changes in the atmospheric circulation in both the Arctic and northern mid-latitudes. Winter 2009-2010 showed a new connectivity between mid-latitude extreme cold and snowy weather events and changes in the wind patterns of the Arctic; the so-called Warm Arctic–Cold Continents pattern.”
