The population of the least developed countries of the Sahel will more than triple from 100 million to 340 million by 2050, and new research projects that today’s extreme temperatures will become the norm by mid-century. The region is characterized by poverty, illiteracy, weak infrastructure, failed states, widespread conflict, and an abysmal status of women. Scenarios beyond 2050 demonstrate that, without urgent and significant action today, the Sahel could become the first part of planet earth that suffers large-scale starvation and escalating conflict as a growing human population outruns diminishing natural resources. National governments and the international community can do a great deal to ameliorate this unfolding disaster if they put in place immediate policies and investments to help communities adapt to climate change, make family planning realistically available, and improve the status of girls and women. Implementing evidence-based action now will be an order of magnitude more humane and cost-effective than confronting disaster later. However, action will challenge some long held development paradigms of economists, demographers, and humanitarian organizations. If the crisis unfolding in the Sahel can help bridge the current intellectual chasm between the economic commitment to seemingly endless growth and the threat seen by some biologists and ecologists that human activity is bringing about irreversible damage to the biosphere, then it may be possible also to begin to solve this same formidable problem at a global level.