Whiff of Trouble

Chemical emissions from biofuel crops could worsen air pollution and yields of food crops, scientists warn in Nature Climate Change.

Farmers are growing more plants that can be processed to make cellulosic ethanol, a biofuel. But some biofuel crops release relatively high amounts of isoprene, a chemical that contibutes to the formation of ozone. Ground-level ozone pollution can cause human health problems and lower crop yields.

The researchers estimated what would happen if Europe planted 72 megahectares of biofuel crops, such as poplar and eucalyptus. Annual isoprene emissions would increase by about 39 percent, they found, making ground-level ozone levels rise as well.

That increase in ground-level ozone would in turn cause about 1,365 extra premature deaths per year, the team predicts. Wheat yields would drop by 3.5 percent and corn yields by 1 percent. The authors estimate that the cost of the additional deaths and crop losses would add up to more than 8 billion US dollars.

Europe is working to reduce ground-level ozone pollution, but the expansion of biofuel crops “could negate much of the effects of present ozone-related pollution control policies,” the team writes. To address the problem, scientists could genetically-engineer these crops to emit less isoprene. And farmers could avoid growing the plants in areas with lots of people or food crops. Roberta Kwok | 8 January 2013

Source: Ashworth, K., Wild, O., and C.N. Hewitt. 2013. Impacts of biofuel cultivation on mortality and crop yields. Nature Climate Change doi: 10.1038/nclimate1788.

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