Cropping Africa's wet savannas would bring high environmental costs

Typography

With the global population rising, analysts and policymakers have targeted Africa's vast wet savannas as a place to produce staple foods and bioenergy groups at low environmental costs. But a new report published in the journal Nature Climate Change finds that converting Africa's wet savannas into farmland would come at a high environmental cost and fail to meet some existing standards for renewable fuels.

With the global population rising, analysts and policymakers have targeted Africa's vast wet savannas as a place to produce staple foods and bioenergy groups at low environmental costs. But a new report published in the journal Nature Climate Change finds that converting Africa's wet savannas into farmland would come at a high environmental cost and fail to meet some existing standards for renewable fuels.

Led by researchers from Princeton University's Woodrow Wilson School of Public and International Affairs and Department of Ecology and Evolutionary Biology, the study finds that only a small percentage of Africa's wet savannas (2 to 11 percent) have the potential to produce staple crops while emitting significantly less carbon dioxide than the world's average cropland. In addition, less than 1 percent of these lands would produce biofuels that meet European standards for greenhouse-gas reductions (taking land conversion into account).

"Many papers and policymakers have simply assumed that Africa's wetter savannas are expendable from an environmental standpoint because they aren't forests,” said co-lead author Tim Searchinger, a research scholar at Princeton's Program in Science, Technology and Environmental Policy (STEP), which is based at the Woodrow Wilson School. "Governments have used this assumption to justify large leases of such lands to produce food for the outside world and large global targets for bioenergy. But when you actually analyze the realistic potential to produce food or bioenergy relative to the losses of carbon and animal biodiversity, the lands turn out not to be low cost."

Even if these lands are converted for agricultural use, the only way Africa could become an exporter of crops is by depriving its own people of food, the researchers report. Farming a large expansion of Africa's savannas — nearly half of the world's remaining savannas — would also have negative impacts on the rich and diverse population of tropical birds and mammals.

The results highlight the need for policies that influence where and to what extent cropland expansion occurs. Likewise, any new cropland that is created for growing staple foods should be prioritized to meet Africa's growing food demands, the researchers report.

"Our paper does not merely analyze the climate costs of different lands, but does so relative to their potential food benefits," said co-lead author Lyndon Estes, associate research scholar at Princeton's Wilson School and STEP. "Because of Africa's rapidly increasing needs for more food, and the high environmental costs of agriculture, it is important to perform this analysis on a more detailed level in each country to determine which lands would produce the most crops for the least environmental cost."

Continue reading at Princeton University.

African savanna image via Shutterstock.