Too warm or too cold? Scientists find clear warming trend

The past two years have been marked by extreme weather in the Northern Hemisphere. It’s been either too warm and too cold. “Snowmaggedon” in the Northeast turned into this summer’s record-breaking sweat fest.

The two extremes don’t cancel each other out, however. On the whole, the warm weather has beaten out the cold in frequency and magnitude, say Scripps Institute of Oceanography scientists. Moreover, they say that the cold weather can be explained by a natural climate cycle having to do with changes in atmospheric pressure at sea level, called the North Atlantic Oscillation. The heat waves could only be explained by a trend towards warmer and warmer weather that is believed to be climate change.

“Over the last couple of years, natural variability seemed to produce the cold extremes, while the warm extremes kept trending just as one would expect in a period of accelerating global warming,” says Scripps climate researcher Alexander Gershunov, a
report co-author in a press release.

Also, while the blizzards stick out in memory, the number of cold events since 2000 were less prominent than in previous decades, the scientists state the paper that’s due to be published in the journal Geophysical Research Letters, a publication of the American Geophysical Union. The winters of 2009-2010 and 2010-2011 were mild, ranking 21st and 34th respectively compared to others since 1970s. The opposite holds true for warm events, which ranked 12th and 4th respectively for those decades.

Is it possible that all this warm weather is making the snow storms seem more extraordinary?

If the human eye could see the heat radiating out of the United States on July 22, 2011, it would look like this image. Photo: NASA