Ozone cuts plant growth, spurs global warming: study

[jpak]

http://www.reuters.com/article/environmentNews/idUSN2527873420070725

WASHINGTON (Reuters) - The affects of greenhouse gas ozone, which has been increasing near Earth's surface since 1850, could seriously cut into crop yields and spur global warming this century, scientists reported on Wednesday.

Ozone in the troposphere -- the lowest level of the atmosphere -- damages plants and affects their ability to absorb carbon dioxide, another global warming gas whose release into the atmosphere accelerates climate change, the researchers wrote in the journal Nature.

While carbon dioxide is blamed for global warming, it also has a beneficial effect on plant growth, and ozone counteracts this effect, said Stephen Sitch, a climate researcher at Britain's Met Office, which deals with meteorology.

"As CO2 (carbon dioxide) increases in the atmosphere, that stimulates plant growth," Sitch said by telephone. He noted that many scientific simulations that predict the impact of global warming have included this effect but "they haven't included the other effect, the negative effect of ozone damaging productivity."

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[OKIsItJustMe]

1. Nature Article

http://www.nature.com/nature/journal/v448/n7152/full/448396b.html

Carbon sinks threatened by increasing ozone

Michael Hopkin

Abstract

Pollutant poisons plants and hampers photosynthesis.
Carbon sinks threatened by increasing ozone

R. KRAUSE/REUTERS

Beijing smog is a sign of rising ozone pollution.

Rising levels of ozone pollution over the coming century will erode the ability of plants to absorb carbon dioxide from the atmosphere, a new climate-modelling study predicts.

Ozone is already known to be a minor greenhouse gas, but the new calculations highlight another, indirect way in which it is likely to influence global warming by 2100. High levels can poison plants and reduce their ability to photosynthesize, says Stephen Sitch of the UK Met Office's Hadley Centre for Climate Prediction and Research in Exeter.

Whereas ozone high in the stratosphere shields Earth from solar ultraviolet rays, high levels of ozone closer in are toxic to plants and animals. Ozone is generated when oxides of nitrogen — chiefly from vehicle exhausts and fossil-fuel power stations — react with other chemicals in the air.

Many of the world's most polluted areas routinely endure ozone concentrations higher than 40 parts per billion, enough to damage plant life. By the end of the century, virtually all the world's populated areas are predicted to be above this threshold.

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