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Crops & Carbon

November 25, 2010

Replacing native plants with crops diminishes the Earth’s ability to store carbon.


The carbon cost of cropland…I’m Bob Hirshon and this is Science Update.

Clearing native plants for farming produces a bumper crop — of carbon dioxide gas. That’s because clear-cutting old growth and tilling the soil releases more carbon than the new crops can absorb. Now, University of Wisconsin ecologist Paul West and his colleagues have quantified this in unprecedented detail.

PAUL C. WEST (University of Wisconsin, Madison):
While we worked with massive amounts of data, the actual math that we used was as simple as balancing a checkbook.

They found that the impact was especially high in the tropics, where expanding farmland releases up to 75 tons of carbon for every ton of food produced. But replacing native plants with crops creates a net carbon emission no matter where you do it. West says the best way to avoid this is to improve and repurpose existing farmland, rather than forging into pristine forests. I’m Bob Hirshon, for AAAS, the science society.