to plant, or not to plant?

Plant trees to soak up carbon dioxide – why not? But it’s more complicated than it sounds. As a meeting of the American Geophysical Union heard in December, computer models show that trees can cool the planet through photosynthesis, but only in the tropics.

The problem is that forests are dark and absorb sunlight, thereby raising the planet’s temperature. Light-coloured landscapes reflect sunlight and cool things down. In the United States and Europe, “the climate benefits of planting will be nearly zero”, according to American ecologist Govindasamy Bala. In the seasonally snow-covered regions at higher latitudes, “planting trees could be actually counter-productive”.

Other left field ideas include waiting for the next ice age, though best guesses put it at 40,000 years away.

The Sunday Age, 18 Feb 2007 – screen copy held by this website