The scenario of planting trees to halt global warming is a
popular one that some researchers warn is a little specious.
Put simply, global warming is due to the sun’s energy being
trapped in our atmosphere by so-called greenhouse gasses such as carbon
dioxide. Our petrol driven cars and aeroplanes and coal-fired power stations
etc, are the prime cause of increased carbon dioxide in the atmosphere.
(Other greenhouse gasses include methane, nitrous oxide and
even water vapour. Pound for pound, methane is the worst – best? - gas in the
atmosphere for trapping the sun’s energy and warming the planet. Methane is
produced in the production of natural gas, coal mining, decomposition of
rubbish, even cows produce a measurable amount of atmospheric methane.)
Trees, (all vegetation in fact), absorb carbon dioxide from
the air and store the carbon in their trunks, branches, leaves and roots and
give off life-sustaining oxygen.
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Part of a Greening Australia re-vegetation project in East Gippsland |
So, it would seem that it is a ‘no brainer’ – plant more
trees and save the planet.
However, when trees die, (all vegetation in fact), their
stored carbon is returned to the atmosphere. Also. their carbon is released to the
atmosphere when they burn.
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When forests burn the carbon in the trees is returned to the atmosphere |
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The carbon in rotting vegetation returns to the environment. |
Added to this, recent calculations estimate that if we
continue to produce carbon dioxide at today’s rate, the number of trees needed
to just barely hold steady the rise in global temperature would be many millions.
These millions of trees would require billions of hectares of land and not all
of the currently available land is suitable for growing trees. It is estimated
that about 10% of the world’s most productive agricultural land would be
required as well, reducing the calories available to the global food system by
as much as 40% - not a good outcome for the nearly 8 billion humans on the
planet!
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Should arable agricultural land be sacrificed for planting trees? |
China’s Green Great Wall is a tree planting project that has
planted more trees than the rest of the world combined. It has been blamed for
absorbing precious ground water reserves in arid regions and for creating worse
smog conditions in Beijing!
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Yefu Mountain National Forest Park in Lujiang county, Anhui
province. (Photo – theasian.asia)
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The unmistakable conclusion is that we cannot halt global
warming without reducing emissions and we cannot plant our way out of climate
change.
National Tree Day
Sunday July 28th
Come and meet the ‘friends’ at Clifford Dr, Drouin, 10 –
12noon
All of Australia’s capital cities and many regional
centres are conducting urban tree planting projects to provide a multitude
of benefits to the environment, the economy and the community.
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