“The violence in Darfur is usually attributed to ethnic hatred. But global warming may be primarily to blame,” concludes the Atlantic Monthly (sub. req).

The article is worth quoting at length, for two reasons. First, the world needs to understand its moral obligation in Darfur if human emissions of greenhouse gases were a major contributing cause to the crisis. Second, the article almost single-handedly contradicts an absurd article that appears in the same issue by Gregg Easterbrook, suggesting that global warming might have as many winners as losers (which I will discuss in a later post). Here are the key parts of the Darfur article:

Why did Darfur’s lands fail? For much of the 1980s and ’90s, environmental degradation in Darfur and other parts of the Sahel (the semi-arid region just south of the Sahara) was blamed on the inhabitants. Dramatic declines in rainfall were attributed to mistreatment of the region’s vegetation. Imprudent land use, it was argued, exposed more rock and sand, which absorb less sunlight than plants, instead reflecting it back toward space. This cooled the air near the surface, drawing clouds downward and reducing the chance of rain. “Africans were said to be doing it to themselves,” says Isaac Held, a senior scientist at the National Oceanic and Atmospheric Administration.

But by the time of the Darfur conflict four years ago, scientists had identified another cause. Climate scientists fed historical sea-surface temperatures into a variety of computer models of atmospheric change. Given the particular pattern of ocean-temperature changes worldwide, the models strongly predicted a disruption in African monsoons. “This was not caused by people cutting trees or overgrazing,” says Columbia University’s Alessandra Giannini, who led one of the analyses. The roots of the drying of Darfur, she and her colleagues had found, lay in changes to the global climate.

The extent to which those changes can be blamed on human activities remains an open question. Most scientists agree that greenhouse gases have warmed the tropical and southern oceans. But just how much artificial warming — as opposed to natural drifts in oceanic temperatures — contributed to the drought that struck Darfur is as debatable as the relationship between global warming and the destruction of New Orleans. “Nobody can say that Hurricane Katrina was definitely caused by climate change,” says Peter Schwartz, the co-author of a 2003 Pentagon report on climate change and national security. “But we can say that climate change means more Katrinas. For any single storm, as with any single drought, it’s difficult to say. But we can say we’ll get more big storms and more severe droughts.”

With countries across the region and around the world suffering similar pressures, some see Darfur as a canary in the coal mine, a foretaste of climate-driven political chaos. Environmental degradation “creates very dry tinder,” says de Waal. “So if anyone wants to put a match to it, they can light it up.” Combustion might be particularly likely in areas where the political or social geography is already fragile. “Climate change is likely to cause tension all over the world,” says Idean Salehyan, a political scientist at the University of North Texas. Whether or not it sparks conflict, he says, depends on the strength, goodwill, and competence of local and national governments …

Among the implications arising from the ecological origin of the Darfur crisis, the most significant may be moral. If the region’s collapse was in some part caused by the emissions from our factories, power plants, and automobiles, we bear some responsibility for the dying. “This changes us from the position of Good Samaritans — disinterested, uninvolved people who may feel a moral obligation — to a position where we, unconsciously and without malice, created the conditions that led to this crisis,” says Michael Byers, a political scientist at the University of British Columbia. “We cannot stand by and look at it as a situation of discretionary involvement. We are already involved.”

The world can ill afford another Darfur. The time to act — on climate change and Darfur — is now!