El Niño and La Niña

The El Niño-Southern Oscillation is a natural cycle that recurs over two to seven years. When surface temperatures in the eastern equatorial Pacific are warmer than usual (an El Niño event), heavy rains hit East Africa and droughts beset India, Indonesia, and Australia. When ocean conditions flip-flop (a La Niña), so do global rainfall patterns. (Fern Gibbons, Woods Hole Oceanographic Institution)