In April, harvest season begins in Southern Africa. An ongoing drought means the season will yield a historically poor crop. Countries including Malawi, South Africa, and Zimbabwe will have major shortfalls of grain. By one count, more than 20 million people in the region already have limited access to food—notwithstanding the drought. Without intervention, the next year will put those people and millions more at risk of malnutrition or even starvation.

But knowing all this makes intervention more possible than ever.

Famines are a powerful illustration of how suddenly nature can undercut a poor or poorly prepared society. We have paid dearly for our failure to respond to them efficiently. Economist Stephen Devereux has estimated 70 million people (pdf) were killed by famine in the 20th century alone.