Feb 052011
Gasohol (Ethanol)
Image by Todd Ehlers via Flickr

Does ethanol in Iowa cause deforestation in Brazil?

HOW green is ethanol? The Renewable Fuels Association (RFA), an American lobby for the stuff, obviously wants voters and politicians to think it is very green indeed. The association’s cool-coloured website plays down claims that ethanol may actually harm the environment. The biggest target of those claims these days is that growing maize to make ethanol causes indirect changes in land use by altering the incentives of other, often foreign, farmers.

Adding ethanol to the traditional markets for maize (food and fodder) inevitably pushes the price up. That encourages farmers, including those in poor countries, to boost production. If some of those farmers plough up savannah or cut down forest to grow the extra crops, the carbon dioxide released from the plants destroyed and soil ploughed up reduce the benefits of substituting the ethanol produced for petrol. If forests that are still growing are cleared, the environment loses the effect of their future uptake of carbon dioxide, too.

The benchmark paper on this, published in Science in February 2008, argues that, if such changes in land use are taken into account, ethanol is twice as carbon-intensive as petrol in the short run. Making ethanol and burning it in a car (without land changes) emits 20% less carbon dioxide than refining and burning petrol. But planting a hectare of ethanol causes someone to clear land for food crops elsewhere. That ethanol crop must provide that modest 20% reduction for 167 years to achieve a net carbon reduction. By then, of course, it is far too late to mitigate climate change.

Bob Dinneen, the RFA’s head, calls these worries “crying wolf” and a “big lie”. A video on the association’s home page has a narrator, brow furrowed, looking puzzled while explaining land-use concerns—how could ethanol cause deforestation “halfway around the world”?—while the text on screen says flatly that ethanol has “no impact on rainforests”. In more sober language, the RFA says that crop yields will increase to meet the maize diverted to ethanol, and points to United Nations’ estimates that there are still billions of hectares of unused arable land around the world.

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