Chilling: Cold Snaps Will Persist in Warming World

Charles Q. Choi LiveScience.com Yahoo News 13 Apr 11;

Although the planet is warming overall, events of extreme cold are still likely to persist on each continent for the next century, researchers say.

The Southeast and Northwest in the United States may be especially vulnerable to these chills, scientists added.

Investigators at Oak Ridge National Laboratory used nine global climate models assuming moderate levels of greenhouse gas emissions (the gases that build up in the atmosphere and trap heat) to compare the climates of 1991 to 2000 with 2091 to 2100.

All nine models found that climate would overall experience warming at the end of the century. However, they forecast that events of extreme cold would still happen, although they would occur less frequently.

"The fact that future extreme cold events will continue to be at least as intense and long-lasting in many regions of the world, even under warming scenarios, may not seem intuitive," researcher Auroop Ganguly, a civil and environmental engineer at Oak Ridge National Laboratory, told Our Amazing Planet.

One can think of the existence of extreme cold events despite an overall trend of global warming much as one would the presence of millionaires in the midst of the Great Depression or the current global economic crisis. Global warming and the Great Depression represent average trends, while cold snaps and millionaires represent extreme cases within those trends.

"Global warming happens over and above natural climate variability, and the latter may cause cold snaps on any given winter and at specific regions of the world even though the overall longer-term global trend is one of warming," Ganguly said.

In addition, "as others have said previously, global warming is probably better understood as 'global weirding' — for example, the changes in temperature patterns are expected to have significant geographical variability," he added.

And global warming is of course not the only factor determining the temperatures at a particular place and time.

"Climate and weather are governed by complex physical mechanisms related to, for example, topography, atmospheric movements and ocean currents, and warming in one region may actually lead to cold extremes in others," Ganguly explained.

Although the researchers found that the Southeast and Northwest may be especially prone to persistence of extreme cold events, they cannot yet pinpoint why, Ganguly said. "We may be able to speculate, based on the related scientific literature, that topography, natural climate variability, atmospheric blocking effects and ocean warming all play a role," he said.

These findings suggest that regional plans in the face of climate change "cannot afford to relax readiness for extreme cold events even as preparations are made to adapt to a generally warming world," Ganguly said.

Ganguly and his colleagues, climate statistician Evan Kodra and climate data mining researcher Karsten Steinhaeuser, detailed their findings online March 16 in the journal Geophysical Research Letters.