That crash — the great rice crisis of 2008 — was a true disaster for some of the poorest people in Asia and West Africa. And the most frightening thing about it is that no one can guarantee that it won't happen again — because the decisions that created it were all, somehow, perfectly reasonable.

Even though there was plenty of rice available around the world because farmers in many places were harvesting record crops, the Indian ban on exports meant that there was less for other countries to buy. Immediately, the price of rice on world markets started to increase.