A Shifting Band of Rain

Some present-day climate patterns are well known, such as the El Nino and La Nina circulations in the Pacific. A lesser known but equally important pattern is the primary precipitation feature on the planet: a band of heavy rainfall that circles the globe in the tropics and migrates north or south seasonally with the angle of the sun. The area in which it moves is known as the Intertropical Convergence Zone. Any change in the earth's temperature, as a result of incoming solar radiation or greenhouse gases, can affect the rain band, which provides the precipitation that feeds equatorial agriculture. Here, Sachs and Myhrvold narrate their trip to numerous islands across the Pacific Ocean to reconstruct the rainfall history.