Global market integration increases likelihood that a future African Green Revolution could increase crop land use and CO₂ emissions

• Published in: Proceedings of the National Academy of Sciences - PNAS 2014-09, Vol.111 (38), p.13799-13804
• Main Authors: Hertel, Thomas W., Ramankutty, Navin, Baldos, Uris Lantz C.
• Format: Article
• Language: English
• Subjects: Africa; agricultural economics; Agricultural land; Asia; Carbon Dioxide; Carbon dioxide emissions; Crop economics; cropland; Crops, Agricultural - economics; Crops, Agricultural - growth & development; deforestation; Farmlands; Food crops; Green revolution; greenhouse gas emissions; Humans; Land use; Latin America; Marketing; markets; Middle East; Models, Biological; Models, Economic; Pollutant emissions; prices; profitability; Social Sciences; Sustainable agriculture; Technological innovation
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.1403543111

Significance Agriculture is a key driver of tropical deforestation, and there is heated debate about whether productivity-enhancing crop innovations can slow such environmental degradation. For fixed food demand, globally higher yields will reduce cropland and hence deforestation. However, regional innovations often boost agricultural profitability and lower prices, thereby leading to cropland expansion in the innovating region. This paper develops a framework for understanding the impact of regional innovations on global land use and the environment. Although the historical Green Revolution in Asia, Latin America, and the Middle East is shown to have been land sparing, a future Green Revolution in Africa could lead to global cropland expansion in the context of a more fully integrated global agricultural economy. There has been a resurgence of interest in the impacts of agricultural productivity on land use and the environment. At the center of this debate is the assertion that agricultural innovation is land sparing. However, numerous case studies and global empirical studies have found little evidence of higher yields being accompanied by reduced area. We find that these studies overlook two crucial factors: estimation of a true counterfactual scenario and a tendency to adopt a regional, rather than a global, perspective. This paper introduces a general framework for analyzing the impacts of regional and global innovation on long run crop output, prices, land rents, land use, and associated CO ₂ emissions. In so doing, it facilitates a reconciliation of the apparently conflicting views of the impacts of agricultural productivity growth on global land use and environmental quality. Our historical analysis demonstrates that the Green Revolution in Asia, Latin America, and the Middle East was unambiguously land and emissions sparing, compared with a counterfactual world without these innovations. In contrast, we find that the environmental impacts of a prospective African Green Revolution are potentially ambiguous. We trace these divergent outcomes to relative differences between the innovating region and the rest of the world in yields, emissions efficiencies, cropland supply response, and intensification potential. Globalization of agriculture raises the potential for adverse environmental consequences. However, if sustained for several decades, an African Green Revolution will eventually become land sparing.