Ramankutty, N., J.A. Foley , J. Norman, and K. McSweeney (2002). The global distribution of cultivable lands: current patterns and sensitivity to possible climate change. Global Ecology and Biogeography, 11, 377-392.

Abstract:

Aim: This study makes quantitative global estimates of the extent of land that is suitable for cultivation based on climate and soil constraints. It further evaluates the sensitivity of suitable croplands to any possible changes in climate, and also the potential shifts in croplands due to possible climate change from increasing greenhouse gas concentrations.

Location: Global,geographically-explicit.

Methods: Spatial data synthesis and analysis,numerical modeling.

Results: We find that there is a cropland “reserve ”of an additional 80%,mainly in tropical South America and Africa. Our climate sensitivity analysis indicates that the southern provinces of Canada, northwestern and north-central states of the U.S.A., northern Europe, southern Former Soviet Union, and the Manchurian plains of China are most sensitive to changes in temperature. The Great Plains region of the U.S.A. and northeastern China are most sensitive to changes in precipitation.We estimate that climate change, as simulated by global climate models, will expand cropland suitability by an additional 20%, mainly in the Northern Hemisphere high latitudes. However, the tropics (mainly Africa, northern South America, Mexico & Central America, and Oceania) will experience a small decrease in suitability due to climate change.

Main Conclusions: There is a large reserve of cultivable croplands,mainly in tropical South America and Africa. However,much of this land is under valuable forests or in protected areas. Furthermore, the tropical soils could potentially lose fertility very rapidly once the forest cover is removed. Regions that lie at the margins of temperatureor precipitation limitation to cultivation are most sensitive to changes in climate. It is anticipated that climate change will result in an increase in cropland suitability in the Northern Hemisphere high latitudes (mainly in developed nations), while the tropics will lose suitability (mainly in developing nations).