Biofuels are the poster children of such good intentions gone terribly awry. Rather than retard global warming, scientists (such as Holly Gibbs, a postdoctoral researcher at Stanford's Woods Institute for the Environment, Matt Strue big from Queen Mary, University of London, and Emily Fitzherbert from the Zoological Society of London and University of East Anglia) are now warning that they may enhance and accelerate it by encouraging deforestation in the tropics. Indeed, the higher the prices fetched by biofuels, the more rainforests are being ferociously decimated in the quest for arable land.

Moreover, biofuels are energy-inefficient: their production consumes more energy than they yield in burning. The disastrous effect they have on food prices is amply documented. Another study demonstrates that their consumption releases more carbon dioxide into the atmosphere than the quantity of fossil fuels that they replace.

This "carbon debt" is especially true if we take into account the gases released by the incineration of trees mowed down to make place for the (often state subsidized) cultivation of biofuels. There is also a "biodiversity debt": up to five-sixths of indigenous species are extinguished once a forest is cleared to make way for oil palm plantations, for instance.

Though much hyped, biofuels should not serve as part and parcel of the energy policy mix. Some wonks suggest that biofuels should be allowed to be grown only on marginal or degraded land. But, this would require enormous investments in fertilizers and other technologies intended to halt soil erosion and nutrient leeching. From the point of view of environmental accounting, such tracts better be re-forested. Forests recycle rainwater, act as carbon skins, prevent floods, and serve as habitats to species, some of them endangered.

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