Carbon Offsetting

Just a footnote to last month's item on this subject: an article in the current Kew Magazine reports on a study, discussed at a meeting of the American Geophysical Union, which suggests that the benefits that come from trees reducing atmospheric carbon dioxide can be outweighed by their capacity to trap heat near the ground.

Computer modelling indicates that trees only really work to cool the planet if they are planted in the tropics. There, they evaporate water to the atmosphere, thus increasing cloud cover which reflects solar radiation back into space. In high latitudes, however, the trees' dark foliage not only absorbs the sunlight, but in snow-covered areas can prevent the snow from reflecting it.

In the temperate forests of Europe and the United States, the climate benefit of planting trees is more or less zero.

There are good reasons for maintaining our temperate forests: they provide habitat for wildlife, protect biodiversity, provide timber and prevent soil erosion. But they won't neutralise that overseas holiday!

Source: Kew Magazine Spring 2007

If you'd like to know more about carbon offsetting and its defects/dangers visit www.carbontradewatch.org