Researchers at Princeton University’s Woodrow Wilson School of Public and International Affairs and Department of Ecology and Evolutionary Biology have found that only 2.0 to 11 percent of Africa’s wet savannas have the potential to produce staple crops while releasing less carbon dioxide than the world’s average croplands. Additionally, the researchers found that less than one percent of these lands would be able to produce biofuels that meet European standards for greenhouse-gas reductions.
Tim Searchinger, a research scholar at Princeton’s Program in Science, Technology and Environmental Policy (STEP), points out that many policymakers are assuming that Africa’s wet savannas are expendable from an environmental standpoint because they aren’t forests, and that is entirely wrong thinking.
Searchinger says: “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.”
The idea of wanting to turn savannas into croplands raises some serious questions, according to the research team. Among them is that farming a large part of Africa’s savannas, almost one-half of the world’s remaining savannas, would have a negative effect on the flora and fauna of the savanna’s ecosystem. Even more problematic is using the converted lands to raise crops for export. This would mean depriving Africa’s own people of food say the researchers.
This very problem was well documented in Karen Hardison’s article in Digital Journal, “Militarization and alternative biofuel drives Ethiopian land-grab.” Large tracts of land are being leased to foreign investors for next to nothing, but none of the lands are being used to meet the needs of feeding a growing population. Hardison cites India as an excellent example of using a mal-nourished country’s land to grow food for export to their own country.
The study’s co-lead author Lyndon Estes, an associate research scholar at Princeton’s Wilson School and STEP says the study highlights the need for policies that prioritize and influence the extent that cropland expansion is done. He says that feeding Africa’s growing population should be the top priority for any new cropland development.
“Our paper does not merely analyze the climate costs of different lands but does so relative to their potential food benefits. 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,” Estes said.
The researchers determined that each country should have an analysis of its own productivity, as well as any environmental impact involved before considering mass land conversions. The overall impact of the release of high levels of stored carbon from cultivated lands and the high cost in terms of lost species really has to be considered. “One basic lesson is that Africa’s wet savannas deserve more environmental respect than they get,” said Phil Thornton, a co-author and senior researcher with the CGIAR Research Program on Climate Change, Agriculture and Food Security.
Africa’s savannas and vegetation zones
In Africa, one can see that savannas cover both sides of the equator, forming a transition zone next to the rainforest regions. Savannas worldwide cover only 15 percent of the mainland surface of the Earth. The type of savanna, such as wet, dry or thorn savannas is determined by the amount of annual rainfall. A good example of a thorn savanna is found in Ethiopia, where the land is a transition zone between a desert to the north and a dry savanna.
The dry savanna is a transition zone between thorn and wet savannas. It is in this zone that we see huge expanses of grasslands and acacia forests and Baobab trees. This region has five to seven moist months a year. It is the wet savanna, with one-half being its man-high grasses and the other half, evergreen forests, that policymakers are drooling over. Nigeria is a good example of a country with wet savannas.
The paper, “High Carbon and Biodiversity Costs from Converting Africa’s Wet Savannas to Cropland,” was published online March 16 in Nature Climate Change.
