Pollution 'fights global warming:
By Matt McGrath
BBC News science reporter
[1] Air pollution may be helping the fight
against global warming by enhancing the
ability of plants to absorb carbon dioxide,
scientists say.
[5] Since the 1960s, increased levels of at-
mospheric pollution have enhanced plant
productivity by as much as one quarter, re-
search has found.
In terms of carbon dioxide, this means
[10] that an extra 10% has been stored in the soil.
The research was published in the
scientific journal, Nature.
It is a common assumption that plants
grow best in clear sunny weather, but
[15] scientists say this is not always the case.
Research has shown that forests and
crops can also thrive in hazy conditions be-
cause clouds and particles in the atmosphere
scatter sun light so that it bathes more
[20] leaves.
That enhances photosynthesis, the process
by which plants turn light and carbon dioxide
into food.
Global dimming
[25] Researchers have now analyzed the im-
pact on plants of the dimmer, hazier skies
that have resulted from increases in air pol-
lution around the world since the 1900s.
They have calculated that this so-called
[30] "global dimming” is responsible for increas-
ing plant productivity by as much as one
quarter from 1960 to 1999.
Dr Lina Mercado from the UK's Centre for
Ecology and Hydrology, the lead author of
[35] the study, said:
“This resulted in a net 10% increase in the
amount of carbon stored by the land once
other effects were taken into account,
she was quoted as saying by the Press As-
[40] sociation.
This study highlights some of the compli-
cations that arise when we try to tackle
global warming.
As the world attempts to reduce the
[45] amount of smog and particulates in the at-
mosphere to improve human health, it will
require even greater efforts to cut back on
carbon dioxide.
This new research shows that plants will
[50] simply not absorb as much carbon dioxide in
cleaner air conditions.
The research will also add weight to ar-
guments about geo-engineering, the idea of
curbing global warming by adding reflective
[55] materials to the atmosphere.
US President Barack Obama's chief
scientific adviser, Professor John Holdren,
recently told reporters that such ideas, once
dismissed as half-baked, would have to be
[60] seriously discussed, such was the scale of
the climate challenge.
Fonte: http://news.bbc.co.uk/2/hi/science/nature/8013709.stm Thursday, 23 April 2009.
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