Climate change could increase the likelihood of civil war in sub-Saharan Africa by over 50 percent within the next two decades, according to a study led by a team of researchers at Stanford University, the University of California-Berkeley, New York University and Harvard University. The study is published in the Nov. 23 online issue of theProceedings of the National Academy of Sciences (PNAS).

The study provides the first quantitative evidence linking climate change and the risk of civil conflict. It concludes by urging accelerated support by African governments and foreign aid donors for new and/or expanded policies to assist with African adaptation to climate change.

"Despite recent high-level statements suggesting that climate change could worsen the risk of civil conflict, until now we had little quantitative evidence linking the two," said Marshall Burke, the study's lead author, a former researcher at Stanford’s Program on Food Security and the Environment. "Unfortunately, our study finds that climate change could increase the risk of African civil war by over 50 percent in 2030 relative to 1990, with huge potential costs to human livelihoods."

The link between climate change and the incidents of civil war in Africa is clear and strong, says Center Fellow David Lobell.

Civil war and climate

In the study, the researchers first combined historical data on civil wars in sub-Saharan Africa with rainfall and temperature records across the continent. They found that between 1980 and 2002, civil wars were significantly more likely in warmer-than-average years, with a 1-degree Celsius increase in temperature in a given year raising the incidence of conflict across the continent by nearly 50 percent.

Building on this historical relationship between temperature and conflict, the researchers then used projections of future temperature and precipitation change to quantify future changes in the likelihood of African civil war. Based on climate projections from 20 global climate models, the researchers found that the incidence of African civil war could increase roughly 55 percent by 2030, resulting in an additional 390,000 battle deaths if future wars are as deadly as recent wars.

All climate models project rising temperatures in coming decades, said study co-author David Lobell, an assistant professor of environmental earth system science and center fellow at the Woods Institute for the Environment at Stanford.

"On average, the models suggest that temperatures over the African continent will increase by a little over 1 degree Celsius by 2030," Lobell added. "Given the strong historical relationship between temperature rise and conflict, this expected future rise in temperature is enough to cause big increases in the likelihood of conflict."

To confirm that this projection was not the result of large effects in just a few countries or due to over-reliance on a particular climate model, the researchers recalculated future conflict projections using alternate data.

"No matter what we tried – different historical climate data, different climate model projections, different subsets of the conflict data – we still found the same basic result," said Lobell, who is also a fellow at the Program on Food Security and the Environment.

"We were definitely surprised that the linkages between temperature and recent conflict were so strong," said Edward Miguel, professor of economics at UC-Berkeley and faculty director of UC-Berkeley's Center for Evaluation for Global Action. "But the result makes sense. The large majority of the poor in most African countries depend on agriculture for their livelihoods, and their crops are quite sensitive to small changes in temperature. So when temperatures rise, the livelihoods of many in Africa suffer greatly, and the disadvantaged become more likely to take up arms."

Understanding the causes and consequences of civil strife in much of the African continent has been a major focus of the social sciences for decades, Miguel said, given the monumental suffering that has resulted.

Near-term impacts

It's easy to think of climate change as a long way off, the researchers said, but their study shows how sensitive many human systems are to small increases in temperature, and how fast the negative impacts of climate change could be felt.

"Our findings provide strong impetus to ramp up investments in African adaptation to climate change, for instance by developing crop varieties less sensitive to extreme heat and promoting insurance plans to help protect farmers from adverse effects of the hotter climate," Burke said.

Applying findings from this study could prove useful to policymakers at the Copenhagen negotiations in December 2009 in determining both the speed and magnitude of response to climate change, the authors said.

"If the sub-Saharan climate continues to warm and little is done to help its countries better adapt to high temperatures, the human costs are likely to be staggering," said Burke, who is now a graduate student at UC-Berkeley's Department of Agricultural and Resource Economics.

Stanford’s Program on Food Security and the Environment is a joint program of the Freeman Spogli Institute for International Studies and the Woods Institute for the Environment.

This article was originally published by the Stanford News Service.