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Plants absorb more carbon under hazy skies
Plants absorbed carbon dioxide more efficiently under the polluted skies of recent decades than they would have done in a cleaner atmosphere, according to new findings published in Nature.
The results of the study have important implications for efforts to combat future climate change, which are likely to take place alongside attempts to lower air pollution levels.
The research team included scientists from the Centre for Ecology & Hydrology, the Met Office Hadley Centre, ETH Zurich and the University of Exeter.
Lead author Dr Lina Mercado, from the Centre for Ecology & Hydrology, said, "Surprisingly, the effects of atmospheric pollution seem to have enhanced global plant productivity from 1960 to 1999. This resulted in a net 10% increase in the amount of carbon stored by the land once other effects were taken into account."
An increase in microscopic particles released into the atmosphere (known as aerosols), by human activities and changes in cloud cover, caused a decline in the amount of sunlight reaching the Earth’s surface from the 1950s up to the 1980s (a phenomenon known as ‘global dimming’).
Although reductions in sunlight reduce photosynthesis, clouds and atmospheric particles scatter light so that the surface receives light from multiple directions (diffuse radiation) rather than coming straight from the sun. Plants are then able to convert more of the available sunlight into growth because fewer leaves are in the shade.
Scientists have known for a long time that aerosols cool climate by reflecting sunlight and making clouds brighter, but the new study is the first to use a global model to estimate the net effects on plant carbon uptake resulting from this type of atmospheric pollution.
Read the full story on the CEH website.
Lina M. Mercado, Nicolas Bellouin, Stephen Sitch, Olivier Boucher, Chris Huntingford, Martin Wild and Peter M. Cox ‘Impact of Changes in Diffuse Radiation on the Global Land Carbon Sink’ will be published in Nature on 23 April 2009 [doi:10.1038/nature07949]
