Trading carbon for food: Global comparison of carbon stocks vs. crop yields on agricultural land
- aCenter for Sustainability and the Global Environment (SAGE), University of Wisconsin, Madison, WI 53726;
- bCenter for Limnology, University of Wisconsin, Madison, WI 53706;
- cProgram on Food Security and the Environment (FSE), The Woods Institute for the Environment, Stanford University, Stanford, CA 94305;
- dConsortium for Science, Policy and Outcomes (CSPO), Arizona State University, Tempe, AZ 85287;
- eWisconsin Program, The Nature Conservancy, Madison, WI 53703; and
- fInstitute on the Environment (IonE), University of Minnesota, St. Paul, MN 55108
See allHide authors and affiliations
Edited by Ruth S. DeFries, Columbia University, New York, NY, and approved October 1, 2010 (received for review July 28, 2010).

Abstract
Expanding croplands to meet the needs of a growing population, changing diets, and biofuel production comes at the cost of reduced carbon stocks in natural vegetation and soils. Here, we present a spatially explicit global analysis of tradeoffs between carbon stocks and current crop yields. The difference among regions is striking. For example, for each unit of land cleared, the tropics lose nearly two times as much carbon (∼120 tons·ha−1 vs. ∼63 tons·ha−1) and produce less than one-half the annual crop yield compared with temperate regions (1.71 tons·ha−1·y−1 vs. 3.84 tons·ha−1·y−1). Therefore, newly cleared land in the tropics releases nearly 3 tons of carbon for every 1 ton of annual crop yield compared with a similar area cleared in the temperate zone. By factoring crop yield into the analysis, we specify the tradeoff between carbon stocks and crops for all areas where crops are currently grown and thereby, substantially enhance the spatial resolution relative to previous regional estimates. Particularly in the tropics, emphasis should be placed on increasing yields on existing croplands rather than clearing new lands. Our high-resolution approach can be used to determine the net effect of local land use decisions.
Footnotes
- 1To whom correspondence should be addressed. E-mail: pcwest{at}wisc.edu.
Author contributions: P.C.W., H.K.G., C.M., C.C.B., S.R.C., and J.A.F. designed research; P.C.W., C.M., and J.W. performed research; P.C.W., H.K.G., and J.W. analyzed data; and P.C.W., H.K.G., C.M., J.W., C.C.B., S.R.C., and J.A.F. wrote the paper.
The authors declare no conflict of interest.
This article is a PNAS Direct Submission.
This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1011078107/-/DCSupplemental.
Citation Manager Formats
Article Classifications
- Biological Sciences
- Sustainability Science