Let’s start with the revolution in Tunisia and the ongoing turmoil in Egypt. Behind the explosion of popular resentments that’s putting once-secure governments at risk is the simple fact that in both countries, and across the Third World more generally, people are having an increasingly hard time getting enough to eat as food prices climb past records set during the last spike in 2008. Plenty of factors feed into the surge in food costs, but one major factor is a string of failed harvests in some of the world’s important grain-producing regions, which in turn has been caused by increasingly unstable weather. Pundits in the US media talk earnestly about the end of an era of cheap food, but what that means in practice is that over a growing fraction of the world, incomes are failing to keep pace with food costs, and as the number of hungry and desperate people grows, so does the pressure toward political explosions.