INTENSIFYING agriculture is never going to be the new rock 'n' roll, but the idea is pretty fashionable right now. Last week a major study led by the UK government's chief scientist John Beddington warned that the only way to feed the world is to produce more food from the same amount of land.
Some say that misses the point: we already produce enough food to feed 10 billion people, if only we didn't waste so much. But there is another argument for intensifying agriculture: to save the rainforests. At last December's climate conference in Cancún, Mexico, many delegates called for investment in farming to be included in REDD, the fund that will pay tropical countries to protect their rainforests and the carbon they lock away.
The argument runs like this. As demand for food increases, farmers - already the biggest destroyers of forest - are likely to chop down yet more trees. So to prevent further destruction, we urgently need to intensify agriculture. As climate economics guru Nicholas Stern put it in Cancún: "Cattle pasture in Brazil has only one animal per hectare. Raise that to two and you can save the Amazon rainforest." The Brazilian government's strategy is based on exactly that premise. The World Bank, which will run the fund, made the same pitch.
The idea that intensifying agriculture relieves pressure on land is sometimes called the Borlaug hypothesis after Norman Borlaug, the pioneer of the green revolution, who first articulated it. But before we go ahead we had better be sure that it is true.
The counter-argument is that farmers don't clear forests to feed the world; they do it to make money. So helping farmers become more efficient and more productive - especially those living near forests - won't reduce the threat. It will increase it.
Tony Simons, deputy director of the World Agroforestry Centre in Nairobi, put it this way in Cancún. "Borlaug thought that if you addressed poverty in the forest border, they'd stop taking their machetes into the forest. Actually, they get enough money to buy a chainsaw and do much more damage."
One recent study seems to bear out this contrarian view. Thomas Rudel of Rutgers University in New Brunswick, New Jersey, compared trends in national agricultural yields with the amount of land under crops since 1990. If Borlaug was right then where yields rose fastest, the rise in cropland should be least. It might even go into reverse.
No such luck. Mostly, yields and cultivated area rose together. Rudel compared the finding to the Jevons paradox, named after the 19th-century economist William Jevons who found that increasing the efficiency of coal burning led to more, not less, coal being burned (Proceedings of the National Academy of Sciences, vol 106, p 20675).
That's not to say intensification isn't needed - the world has to be fed, after all. But it won't necessarily save the forests. Any climate protection scheme that assumes it does is likely to be handing out money for nothing.
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