“Warming Hole” Over the Eastern U.S. Due to Air Pollution

[tabatha]

Temperatures are increasing on a global scale, but at the regional level, the story gets complicated. In the central and eastern United States, for example, warming has not kept pace with other parts of the world over much of the last century.

As shown in the lower map, which is based on data from NASA’s Surface Temperature Analysis (GISTEMP), parts of the United States even cooled between 1930 and 1990. Areas of the greatest cooling are blue; those that warmed are red. Climate scientists have taken to calling the large area of cooling a “warming hole” because the areas surrounding it have warmed at a faster rate.

For more than a decade, researchers have puzzled over what’s causing the warming hole over the United States. Previous research has suggested natural variations in sea surface temperatures might be responsible, but a new study puts the focus on sulfates, a type of aerosol produced by coal power plants that’s known for causing acid rain. Sulfates are light-colored, and they cause cooling by scattering and reflecting sunlight. They also lower temperatures indirectly by making clouds more reflective and long-lasting.

The researchers, led by Eric Leibensperger when he was at Harvard University, used global climate models to estimate the cooling effect sulfates have had on the climate of the United States since 1950. As seen in the top map, they found that between 1970 and 1990—the period when sulfates were at their highest levels—average temperatures were nearly 1°Celsius (1.8°Fahrenheit) cooler in a core area centered on Arkansas and Missouri and about 0.7°Celsius cooler in a larger tear-drop region throughout the Midwest and Mid-Atlantic. The cooling effect extended into the North Atlantic Ocean as well; sulfate pollution lowered sea surface temperatures there by 0.3°Celsius.

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NASA Earth Observatory image by Jesse Allen, based on data provided by Eric Leibensperger (Harvard University). Caption by Adam Voiland.

http://www.flickr.com/photos/gsfc/7221961778/

[unblock]

1. egads, i can't wait for the right-wing to say pollution is the cure for global warming!

"pollute, baby, pollute!"

[tabatha]

2. Check this out:

http://www.treehugger.com/clean-technology/pumping-sulfate-particles-into-the-stratosphere-not-such-a-hot-idea-after-all.html