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The growth of plants around the world might be stunted because of air pollution by the end of the century, a new report concludes.

 

Increasing concentrations of ozone from pollution will damage plants and keep them from breathing the odorless, invisible gas they need to live, some say. The change would occur despite the carbon dioxide boost to greenery that some have said global warming will provide.

 

The result is carbon dioxide concentrations would build up in the atmosphere even more than expected, the study researchers say. But other factors, including ozone, come into play and may prevent plants from taking up as much carbon dioxide as they need.

 

Some scientists have said that one of the benefits of global warming will be a boom in the plant population brought on by higher carbon dioxide levels that feed plants through photosynthesis. Plants do in fact act as an important carbon sink, or means of taking the potent greenhouse gas from the atmosphere.

 

Previous models have included the beneficial effects to plants, "but they haven't included the negative effects," said Stephen Sitch of the UK Met Office, lead author of the new study, published in the July 25 online edition of the journal Nature.

 

Plants normally take in ozone and other gases through their stomata, or pores, but when ozone levels surpass a certain amount, the gas causes cellular damage inside the plant's leaves, and they become visibly damaged with brown splotches. The ozone also reduces the rate of photosynthesis in the plant and cripples its ability to grow.

 

"In effect the cells have been disrupted," Sitch told LiveScience. "Essentially the photosynthetic apparatus has been damaged."

 

(Xinhua News Agency via Agencies July 28, 2007)