With rainfall down by up to 30% over 40 years and the Sahara advancing by over a mile every year, tensions between farmers and herders over disappearing pasture and evaporating water holes threaten to reignite the war between north and south Sudan. The southern Nuba tribe, for example, have warned they could "restart the war" because Arab nomads - pushed southwards into their territory by drought - are cutting down trees to feed their camels.
The UNEP investigation into links between climate and conflict in Sudan predicts that the impact of climate change is likely to go far beyond its borders. It found there could be a drop of up to 70% in crop yields in the most vulnerable areas of the Sahel. "It doesn't take a genius to work out that as the desert moves southwards there is a physical limit to what [ecological] systems can sustain, and so you get one group displacing another." said Achim Steiner, UNEP's executive director
The immediate cause of the Darfur conflict was a regional rebellion, to which Khartoum responded by recruiting Arab militias to wage a campaign of ethnic cleansing against African civilians. The UNEP study suggests the true genesis of the conflict pre-dates 2003 and is to be found in failing rains and creeping desertification. It found that: The desert in northern Sudan has advanced southwards by 60 miles over the past 40 years; Rainfall has dropped by 16%-30%;; Yields in the local staple, sorghum, could drop by 70%.
UN secretary-general, Ban Ki-moon, argued: "Almost invariably, we discuss Darfur in convenient military and political shorthand - an ethnic conflict pitting Arab militias against black rebels and farmers. Look to its roots, though, and you discover a more complex dynamic. Amid the diverse social and political causes, the Darfur conflict began as an ecological crisis, arising at least in part from climate change."
In turn, the Darfur conflict has exacerbated Sudan's environmental degradation, forcing more than two million people into refugee camps. Deforestation has been accelerated while underground aquifers are being drained. The UNEP report warns that no peace will last in the area without sustained investment in containing environmental damage and adapting to climate change. Mr Steiner said: "Simply to return people to the situation there were in before is a high-risk strategy."