Sir

The “true culprit” in the Darfur crisis is the National Islamic Front, according to two recent News stories ('Darfur's climate roots challenged' Nature 447, 1038; doi:10.1038/4471038b 2007, and 'Darfur lake is a “mirage”' Nature 448, 394–395; doi:10.1038/448394a 2007).

Political scientists understandably point to specific parties, leaders and military factions to account for a specific crisis such as Darfur. It is also understandable that they do not want to make excuses for perpetrators of violence. Still, as quoted, they have gone too far in the opposite direction. They seem to overlook the point that Darfur's extreme poverty, rising population, growing water stress and desertification are all important contributors to the Darfur crisis.

The most authoritative recent study of the subject — the United Nations Environment Programme's report Sudan: Post-Conflict Environmental Assessment (http://www.unep.org/sudan) — rightly notes that desertification, land degradation and climate change are major factors in the crisis, and appropriately comments that they are “generally contributing factors only, not the sole cause for tension”. The report also states that long-term peace in the region will become possible only if environmental and livelihood issues are resolved.

These findings are in line with a growing number of studies that find extreme poverty, falling incomes and failing rains are strong predictors of outbreaks of violence in Africa. An excellent new book Too Poor for Peace? (eds L. Brainard and D. Chollet, Brookings Institution Press, 2007) notes that recent research strongly favours the claim that these are the crucial drivers of conflict in less developed countries; much less solid evidence implicates political repression.

It is important that considerations of ecology, climate and extreme poverty are integrated with political analyses of conflict. This is especially the case as demographic pressures hit against resource limitations and climate change in the Horn of Africa and elsewhere.