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06 Oct 07
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<!--******** "Todays date" component ******** -->Wednesday, October 20, 1999 Published at 22:49 GMT 23:49 UK<!--******** END COMPONENT ******** -->
Sci/Tech
Trees 'will not avert climate change'
The world's forests can buy a little time, before they start adding to the warming
By Environment Correspondent Alex KirbyHopes that planting trees could absorb significant amounts of carbon dioxide (CO2) and so help to sl >ow down global warming look set to be dashed.
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Hopes that planting trees could absorb significant amounts of carbon dioxide (CO2) and so help to sl > >ow down global warming look set to be dashed
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Hopes that planting trees could absorb significant amounts of carbon dioxide (CO2) and so help to sl
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down global warming look set to be dashe
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l > > >ow down global warming look set to be dashe >d.
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sl > > >ow
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New forests are temporary reservoirs that can buy valuable time to reduce industrial emissions, not permanent offsets to these emissions."
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Annual CO2 emissions from human activity add just over six billion tonnes of carbon to the atmosphere, of which about a third is absorbed by the world's forests.
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Governments thought this meant that more trees would simply mean more carbon absorption, leaving them more leeway to carry on polluting.
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The problem is that although trees absorb CO2 during photosynthesis, they also release it back into the air when plant matter breaks down the sugars they have made. This process is called respiration.
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Crucially, respiration increases in response to temperature rises, which are triggered by the rising levels of CO2. Many scientists believe that respiration may be about to accelerate, turning the forests from sinks to sources of carbon.
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