Many experts believe that the Sahel has huge potential to sustain crops and livestock if its water resources were managed properly. Scattered among the sand dunes and scrub land, there are thousands of oases and valleys where crops can grow. But less than 10 per cent of the population has access to these oases, which are owned by a privileged few. And since the water is deep underground, the owners often lack the money to dig wells and pump out the water for crops.
In the region surrounding Mao in the Sahel of western Chad, 750 oases are underused because their owners cannot afford to dig wells, according to the UN's Food and Agriculture Organization. It estimates that only 10 per cent of the oases are properly developed for agricultural use.
Another key factor is the government's preference for military spending. Chad has received billions of dollars in oil revenue in recent years (it is the sixth-biggest African supplier of oil to the United States), yet most of this revenue is spent on its security forces, despite its earlier promises to spend the oil money on poverty alleviation.
"People think Chad is a rich country because of its oil - and it's true," says Jean-Baptiste Ndikumana, the Unicef deputy representative in Chad. "If they used this money for social services, there could be some improvement. Instead, they use it for weapons."
Poor levels of education are another crucial problem. Knowing little about nutrition, many people in the Sahel turn to traditional healers when their children are starving. The "healers" usually do more harm than good: They cut incisions in children's mouths or burn their bottoms to "treat" diarrhea.
Grandmothers, meanwhile, encourage their pregnant daughters to eat less food so that their babies will be smaller; or they advise mothers to give water, instead of milk, to newborns. Both are dangerous practices. Breastfeeding is one of the best ways to improve a child's health, yet only about 3 per cent of Chad's children are exclusively breastfed in their first six months. And because of cultural traditions, women with starving children are reluctant to travel to a feeding centre without the permission of their husbands, who are often unreachable because they have migrated in search of work.
Education and agricultural development are the keys to saving the people of the Sahel from climate change. Yet only a small handful of international agencies are present here, in contrast to the hundreds of agencies in Haiti or Afghanistan.
There are no dramatic earthquakes or civil wars to draw attention to the Sahel - only the slow grind of climate change, wreaking its gradual chaos on the land. Relief agencies tend to respond late, or not at all. The UN was aware of the drought in Chad in the fall of 2009, yet it did not send emergency aid until the spring of this year. "We came too late," Mr. Siblot admits. "We wasted three months, scratching our heads and trying to decide on a response."
The FAO is one of the UN agencies that should be helping Chad to improve its agricultural productivity, yet it has only a small presence here. In effect, the UN and the world's donor countries have channelled their funds to emergency aid, rather than long-term agricultural development - which means that Chad will always be dependent on aid. "We are saving lives, but we are not solving the problems," says Mr. Ndikumana of Unicef.
The Sahel may symbolize the future of foreign aid: responding to climate-related crises that leave millions at risk of hunger and death. The solution, as Mr. Siblot acknowledges, is to do more than "dumping food" into a region. There needs to be much heavier investment in education and agriculture, so that massive numbers of people aren't forced to abandon their homes. And if a regime prefers to spend its billions on soldiers and military weaponry, the buyers of its oil might have to use their influence to press for new priorities. Otherwise, the vast human migration in places such as the Sahel will spin out of control forever.
Geoffrey York is The Globe and Mail's Africa bureau chief.