El Niño is a warm surface current that sometimes flows off the west coast of South America and results in prolonged increases in sea-surface temperatures along the coast of Peru and in the equatorial eastern Pacific Ocean. It is believed to be closely associated with irregular variations in the global weather system and it occurs approximately every 7 to 11 years. It is called El Niño (Spanish for "the Christ Child") because it often begins around Christmas.

The flow of warm water prevents plankton-rich cold water from the Antarctic rising to the surface off the coasts of Chile and Peru. As a result, fish don't come to feed and local fishermen make no catches. The wider consequences of El Niño can be catastrophic. The current is associated with short-term changes in worldwide climate patterns, and may cause drought in places such as Australia; flooding and sever winters in North America; and violent tropical cyclones in the Pacific Ocean. Some scientists fear that global warming may be making El Niño occur more frequently.