12, Feb, 2012

Less Smog Means More Global Warming

Written by spacetravel.org

Thursday, 12 May 2005 20:32

Climate scientists say that in the past half-century, rising levels of greenhouse gases, such as carbon dioxide, have warmed the Earth. However, a corresponding increase in smog particles has shaded the Earth, partly offsetting the warming. Martin Wild at the Institute for Atmospheric and Climate Science in Zurich, Switzerland says that this trend has now reversed, and there is no longer a dimming to counteract the greenhouse effect.

Wilds team analyzed data from a global network of instruments measuring the radiation reaching the Earths surface and found that on average the surface had brightened about 4 percent over the past decade. Rachel Peaker, a meteorologist at the University of Maryland in College Park and her colleagues have backed up these figures with satellite measurements from 1983 to 2001. The satellite records show that while dimming occurred in the early years, the trend reversed in 1992.

Cleaner air is letting in more solar radiation, especially in Europe and the former Soviet Union, where there has been industrial decline. However, the same trend emerges in North America, Japan, Australasia and most recently, China, where smog has been kept in check despite rapid industrialization.

Wild states that this does not mean that returning to smoggy air will halt global warming. He points out that carbon dioxide remains in the atmosphere for a century or more, while aerosols typically stay in the atmosphere for only a few days. This would mean that smog would have to continuously become thicker, and become even more of a health threat, to counteract rising levels of carbon dioxide.

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