Pollution reduces carbon dioxide levels?
The world’s vegetation soaked up carbon dioxide more efficiently under the polluted skies of recent decades than it would have under a pristine atmosphere, a new analysis in the April 23 Nature suggests. The trend hints that relying on forests and other vegetation to sequester carbon may not be effective if skies continue to clear, researchers say.
Major volcanic eruptions throw large quantities of aerosols, such as small bits of fractured rock and droplets of sulfuric acid, high into the atmosphere. Those particles scatter incoming solar radiation, preventing some of it from reaching Earth’s surface and thereby cooling climate temporarily (SN: 11/5/05, p. 294).
That scattering also, however, boosts how much carbon vegetation takes in, says Lina M. Mercado, an ecosystem modeler at the Centre for Ecology & Hydrology in Wallingford, England. Although aerosols, including many types of air pollution, decrease the overall amount of light falling onto a tree, the particles diffuse the radiation that reaches the ground so that it actually illuminates more leaves. In that case, leaves below the tree’s outer canopy are less likely to be shaded. . . . .
Labels: Environment, GlobalWarming
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