While we agree with N. Borlaug that the Green Revolution increased crop productivity in certain regions of the world (Editorial, "Feeding a hungry world," 19 October 2007, p. 359), its large-scale negative social and environmental effects now threaten future food production.
The Green Revolution model of agriculture promotes the exploitation of natural resources. The trade-off for chemical-dependent yield increases is degraded lands, contaminated and overdrawn water supplies, diminished crop and agroecosystem diversity, and worrying declines in soil fertility across the globe (1). The model seriously compromises its own future viability and could endanger future food production (2).
Claims that the Green Revolution spared land from farming and effectively spared land for nature are questionable (3). Often, land intensification prevents biodiversity conservation in neighboring lands (4) and causes major environmental problems downwind and downstream of agriculture. Experience in Mexico’s Sea of Cortez, referred to as the "Aquarium of the World" due to its richness in biological diversity, highlights the present and future vulnerability of ecosystems to agricultural runoff (5). Here, overuse of agrochemicals in what is one of the birthplaces of the Green Revolution has led to serious nitrogen pollution and algal blooms.
Genetic engineering currently serves to reinforce rather than resolve the environmental mistakes of the Green Revolution. Crops which are engineered to tolerate herbicides merely prolong an ecologically damaging, chemical-dependent agricultural system (6).
N. Borlaug assumes that we merely need to produce more food and people will eat. Yet any historian of the Green Revolution will concede that its productivity gains were not shared equitably and that more production does not necessarily lead to fewer hungry people. (7, 8). Despite localized productivity increases, close to a billion people were left behind by this "revolution" and remain without sufficient food to eat. More of the same environmentally destructive approaches will not magically start to feed people.
The new challenges facing agriculture require new approaches. A 21st century approach will integrate people, biodiversity, and environment and be based on agroecological principles (1). There are many examples, especially in developing countries, where farmers maintain high yields from their land in biologically- and biodiversity-based systems that ensure both a healthy livelihood and environment (9, 10). Long-term sustainability in agricultural production will depend substantially on not repeating the mistakes of the last half-century.
Reyes Tirado
Greenpeace Research Laboratories, University of Exeter, UK.
Doreen Stabinsky
Greenpeace International, College of the Atlantic, Bar Harbor, ME, USA.
References
1. G. P. Robertson, S. M. Swinton, Frontiers in Ecology and the Environment 3, 38 (2005).
2. D. Tilman, K. G. Cassman, P. A. Matson, R. Naylor, S. Polasky, Nature 418, 671 (2002).
3. P. A. Matson, P. M. Vitousek, Conservation Biology 20, 709 (2006).
4. M. M. Mayfield, G. C. Daily, Ecological Applications 15, 423 (2005).
5. J. M. Beman, K. R. Arrigo, P. A. Matson, Nature 434, 211 (2005).
6. S. Krimsky, R. Wrubel, Agricultural Biotechnology and the Environment: Science, Policy, and Social Issues (University of Illinois Press, Urbana, IL, 1996).
7. D. K. Freebairn, World Development 23(2) 265 (1995).
8. A. Sen, Poverty and Famines: An Essay on Entitlement and Deprivation (Oxford University Press, Oxford, UK, 1981).
9. J. N. Pretty, J. I. L. Morison, R. E. Hine, Agriculture, Ecosystems and Environment 95, 217 (2003).
10. C. Badgley et al., Renewable Agriculture and Food Systems 22, 86 (2007).
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