But every few years, after rain has multiplied the vegetation, they suddenly swarm. One swarm in north Africa in 1988 was measured at 75 miles by 16 miles. It covers everything like a thick, natural fabric. All you hear is chewing. Scientists working together have helped limit locust plagues around the Mediterranean, and meteorologists warn governments and each other about windstorms and floods, but drought is another matter.
Droughts tend to do their worst on land that is already arid, and where societies are on the margin.
In a world where rain is rare, people can cope with a dry year or two, but then, quite quickly, the wells fail, and the livestock begins to die. The first sign of famine is usually a sudden series of grain price rises in local markets. Within weeks, gaunt figures begin to appear on the edges of towns. Global warming will magnify all these problems. Rising sea levels will multiply storm surges and higher sea surface temperatures will guarantee more frequent hurricanes.