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)
