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Study: Pollution helps plants absorb C02

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  • Sunlight scattered by pollution means less plants left in the shade, study finds
  • Study: Plant productivity rose by as much as a quarter from 1960 to 1999
  • Cleaning up air pollution could make efforts to reduce CO2 even harder
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(CNN) -- Plants absorbed carbon dioxide more efficiently under polluted skies than they would have done in a cleaner atmosphere, according to new findings published this week in Nature magazine.

Smoggy skies, green leaves: Pollution has helped plant growth, according to a new study.

Smoggy skies, green leaves: Pollution has helped plant growth, according to a new study.

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 Center for Ecology & Hydrology, the Met Office Hadley Centre, ETH Zurich and the University of Exeter.

"Surprisingly, the effects of atmospheric pollution seem to have enhanced global plant productivity by as much as a quarter from 1960 to 1999. This resulted in a net 10 percent increase in the amount of carbon stored by the land once other effects were taken into account," said lead author Dr Lina Mercado, from the Center for Ecology & Hydrology in a press statement.

Reductions in sunlight reduce photosynthesis, but clouds and atmospheric particles scatter sunlight, meaning plants are then able to convert more of the available sunlight into growth because fewer leaves are in the shade.

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 1950's up to the 1980's -- a phenomenon known as "global dimming."

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 intake resulting from this type of atmospheric pollution.

"Although many people believe that well-watered plants grow best on a bright sunny day, the reverse is true. Plants often thrive in hazy conditions such as those that exist during periods of increased atmospheric pollution," co-author Dr. Stephen Sitch from the University of Leeds said to the press.

The research team also considered the implications of these findings for efforts to avoid dangerous climate change.

"As we continue to clean up the air in the lower atmosphere, which we must do for the sake of human health, the challenge of avoiding dangerous climate change through reductions in CO2 emissions will be even harder," said co-author Professor Peter Cox of the University of Exeter in a press statement.

Under an environmentally friendly scenario in which sulphate aerosols decline rapidly in the 21st century, the researchers found that by cleaning up the atmosphere, even steeper cuts in global CO2 emissions would be required to stabilize carbon dioxide concentrations below 450 parts per million by volume.

"Different climate changing pollutants have very different direct effects on plants, and these need to be taken into account if we are to make good decisions about how to deal with climate change," said Cox.

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