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Green Revolution research saved an estimated 18 to 27 million hectares from being brought into agricultural production
Edited by Kenneth G. Cassman, University of Nebraska, Lincoln, NE, and accepted by the Editorial Board December 16, 2012 (received for review June 15, 2012)

Abstract
New estimates of the impacts of germplasm improvement in the major staple crops between 1965 and 2004 on global land-cover change are presented, based on simulations carried out using a global economic model (Global Trade Analysis Project Agro-Ecological Zone), a multicommodity, multiregional computable general equilibrium model linked to a global spatially explicit database on land use. We estimate the impact of removing the gains in cereal productivity attributed to the widespread adoption of improved varieties in developing countries. Here, several different effects—higher yields, lower prices, higher land rents, and trade effects—have been incorporated in a single model of the impact of Green Revolution research (and subsequent advances in yields from crop germplasm improvement) on land-cover change. Our results generally support the Borlaug hypothesis that increases in cereal yields as a result of widespread adoption of improved crop germplasm have saved natural ecosystems from being converted to agriculture. However, this relationship is complex, and the net effect is of a much smaller magnitude than Borlaug proposed. We estimate that the total crop area in 2004 would have been between 17.9 and 26.7 million hectares larger in a world that had not benefited from crop germplasm improvement since 1965. Of these hectares, 12.0–17.7 million would have been in developing countries, displacing pastures and resulting in an estimated 2 million hectares of additional deforestation. However, the negative impacts of higher food prices on poverty and hunger under this scenario would likely have dwarfed the welfare effects of agricultural expansion.
Footnotes
- ↵1To whom correspondence should be addressed. E-mail: james.stevenson{at}fao.org.
Author contributions: J.R.S., D.B., T.K., and M.M. designed research; N.V. performed research; J.R.S., N.V., D.B., T.K., and M.M. analyzed data; and J.R.S., N.V., D.B., T.K., and M.M. wrote the paper.
The authors declare no conflict of interest.
This article is a PNAS Direct Submission. K.G.C. is a guest editor invited by the Editorial Board.
*The quote from Borlaug is: “If the global cereal yields of 1950 still prevailed in 2000, we would have needed nearly 1.2 billion more hectares of the same quality, instead of the 660 million hectares used, to achieve 2000’s global harvest.” (ref. 8, p. 359). We actually think that the “more” in this sentence is a typographical error. Borlaug’s argument fits better with a total area of cereals in 2000 of 1.2 billion in absence of observed yield increases. This suggests a land-saving effect of 560 million hectares (1,220 million ha − 660 million ha), rather than 1.2 billion additional hectares.
This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1208065110/-/DCSupplemental.
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