TALKS to salvage the Kyoto Protocol could be undermined before they even
start by research suggesting that planting forests to curb global warming could
backfire.
The world鈥檚 nations are due to meet in Bonn next week to thrash out ways to
combat climate change. The protocol gives governments the option to plant trees
to soak up carbon dioxide, rather than cutting emissions of the greenhouse
gas.
But this provision is deeply flawed, warns Richard Betts of Britain鈥檚
Meteorological Office. He says it doesn鈥檛 take into account other ways that new
forests can affect climate. 鈥淐arbon accounting alone will overestimate the
contribution of afforestation to reducing climate warming,鈥� he told New
快猫短视频.
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This week, Betts presented the first detailed calculations showing that
planting trees across the snow-covered swathes of Siberia and North America will
heat the planet rather than cool it. And even away from the tundra, the cooling
potential of forests is much less than previously supposed, he told a climate
conference in Amsterdam.
His findings may further undermine support for the Kyoto Protocol. Several
industrialised countries are wavering following the withdrawal of the US from
the proposed treaty earlier this year.
Green forest canopies reflect much less solar radiation than most other land
surfaces. They also absorb more, heating the Earth鈥檚 surface. This effect is
greatest where forests replace snowy tundra, which normally reflects large
amounts of solar radiation. Betts calculates that at northern latitudes, warming
as a result of planting forests will overwhelm any cooling effect due to the
trees soaking up CO2.
Both Canada and Russia want to plant forests in their empty tundras to help
meet their Kyoto commitments, because a hectare of immature forest can absorb
more than 100 tonnes of carbon each year, despite growing slowly. But Betts
calculates that the net warming effect of heat-absorbent forests in both regions
is equivalent to an annual emission of 75 tonnes of carbon per hectare.
His new calculations also halve estimates for the carbon sink potential of
western European forests. 鈥淓ven in places where the cooling effect is still
dominant,鈥� says Betts, 鈥渢he cooling influence is generally much smaller than
expected when considering carbon sequestration alone.鈥�
So should some countries be destroying forests instead? 鈥淚 am not suggesting
that we deforest,鈥� says Betts. 鈥淏ut afforestation is not always an effective
alternative to cutting fossil fuel emissions.鈥�
