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. 2013 May 21;110(21):8363-8.
doi: 10.1073/pnas.1208065110. Epub 2013 May 13.

Green Revolution research saved an estimated 18 to 27 million hectares from being brought into agricultural production

James R Stevenson  1 , Nelson Villoria, Derek Byerlee, Timothy Kelley, Mywish Maredia
Affiliations

Green Revolution research saved an estimated 18 to 27 million hectares from being brought into agricultural production

James R Stevenson et al. Proc Natl Acad Sci U S A. .

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.

Keywords: agricultural productivity; land-use change.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Fig. 1.
Fig. 1.
Negative shocks to TFP growth in developing country agriculture during the period 1965–2004 equivalent to removing the observed productivity gains from crop germplasm improvement [estimated by Evenson (17), pp. 466–467]. The lower-bound TFP shocks are given by the segment between the origin and the white line. The additional segment represents the upper-bound TFP shocks.
Fig. 2.
Fig. 2.
Percentage changes relative to the baseline year (2004) in production, price, imports, and harvested area aggregated using as weights: output values (for prices), physical output (for production), and physical area. For each scenario the values for the lower and upper bounds are separated by a white line.
Fig. 3.
Fig. 3.
Estimated land-use/land-cover change in 2004 under two scenarios: lower bound (Left) and upper bound (Right) effects of crop germplasm improvement. Whiskers reflect 95% CIs to uncertainty in the parameters regulating the ease with which yield responds to increases in crop prices, the assumed productivity of the new forests and pastures that enter into production, the ease with which land is transformed from forests and pastures into crops, and the ease with which land switches among crops.
Fig. 4.
Fig. 4.
Estimated increase in total GHG emissions (in Gt of CO2) for the period 1965–2004 from land-cover change. Two scenarios and CIs as per Fig. 3.
Fig. 5.
Fig. 5.
Estimated agricultural emissions from changes in input use, agricultural soils, and rice cultivation associated with a counterfactual of no crop germplasm improvement over the period 1965–2004. Two scenarios and CIs as per Fig. 3.
See this image and copyright information in PMC

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