A little more than a week ago, leaders of the world's industrialized nations met for their annual summit in Heiligendamm, Germany. Our modest goal: to win a breakthrough on climate change. And we got it-an agreement to cut greenhouse gases by 50 percent before 2050. Especially gratifying, for me, is that the ways and means will be negotiated via the United Nations, the better to ensure that our efforts will be mutually reinforcing. This week, the global focus shifted. Tough but patient diplomacy produced another win, as yet modest in scope but large in humanitarian potential. That's the plan, accepted by Sudanese President Omar Al-Bashir, to at long last deploy a joint United Nations-African Union peacekeeping force in Darfur. This agreement, too, is personally gratifying. I have made Darfur a top priority and have invested considerable effort, often far from public view, in working by myriad small steps toward this goal. Clearly, uncertainties remain. This deal, like others before it, could yet come undone. It could be several months before the first new troops arrive, and longer before the full 23,000 contingent is in place. Meanwhile, the fighting will likely go on, even if less intensely and despite our many calls for a ceasefire. Still, in a conflict that has claimed more than 200,000 lives - amid four years of diplomatic inertia - this is significant progress, especially considering that it has come in a mere five months. It would be natural to view these as distinct developments. In fact, they are linked. Almost invariably, we discuss Darfur in a convenient military and political short-hand-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 many diverse social and political causes of the Darfur conflict, it's worth noting that it began as an ecological crisis, arising at least in part from climate change. Two decades ago, the rains in southern Sudan began to fail. According to UN statistics, average precipitation has declined some 40 percent since the early 1980s. Scientists at first considered this to be an unfortunate quirk of nature. But subsequent investigation found that it coincided with a rise in water temperatures of the Indian Ocean, disrupting seasonal monsoons. This suggests that the drying of sub-Saharan Africa derives, to some degree, from man-made global warming. It is no accident that the violence in Darfur erupted amid the drought. Until then, Arab nomadic herders had lived amicably with settled farmers. A recent article by Stephan Faris, in the Atlantic Monthly, describes how black farmers would welcome the herders as they crisscrossed the land, grazing their camels and sharing wells. But once the rains stopped, farmers fenced their land for fear it would be ruined by the passing herds. For the first time in memory, there was no longer enough food and water for all. Fighting broke out. By 2003, it evolved into the full-fledged tragedy we witness today. But it is important to remember how it began, for that is a key to the future. A UN peacekeeping force will help moderate the violence and keep humanitarian aid flowing, saving many lives. Yet that is only a first step, as I emphasized to my colleagues at the recent summit in Germany. Any peace in Darfur must be built on solutions that go to the root causes of the conflict. We can hope for the return of more than 2 million refugees. We can safeguard villages and help rebuild homes. But what to do about the essential dilemma - the fact that there's no longer enough good land to go around? A political solution is required. My special envoy for Darfur, Jan Eliasson, and his AU counterpart, Salim Ahmed Salim, have worked out a road map, beginning with a political dialogue between rebel leaders and the government. The initial steps in this process could be taken by this summer. Ultimately, however, any real solution to Darfur's troubles involves something more -sustained economic development. Precisely what shape that might take is unclear. But we must begin thinking about it, now. New technologies can help, such as genetically modified grains that thrive in arid soils or new irrigation and water storage techniques. There must be money for new roads and communications infrastructure, not to mention health, education, sanitation and social reconstruction programs. The international community needs to help organize these efforts, working with the government of Sudan as well as the host of international aid agencies and NGOs working so heroically on the ground. The stakes go well beyond Darfur. Jeffrey Sachs, the Columbia University economist and one of my senior advisers, notes that the violence in Somalia grows from a similarly volatile mix of food and water insecurity. So do the troubles in Cote d'Ívoire and Burkina Faso. There are many other parts of the world where such problems will arise, for which any solutions we find in Darfur will be relevant. We have made slow but steady progress in recent weeks and months. The people of Darfur have suffered too much, for too long. Now the real work begins. Mr. Banis Secretary-General of the United Nations
