(Oceanography) A weak warm ocean current that flows south off the coast of Ecuador at Christmas time.
Warm ocean surge of the Peru Current, so called because it tends to occur at Christmas, recurring every 5–8 years or so in the E Pacific off South America. It involves a change in the direction of ocean currents, which prevents the upwelling of cold, nutrient-rich waters along the coast of Ecuador and Peru, killing fishes and plants. It is an important factor in global weather.
El Nińo is believed to be caused by the failure of trade winds and, consequently, of the ocean currents normally driven by these winds. Warm surface waters then flow in from the east. The phenomenon can disrupt the climate of the area disastrously, and has played a part in causing famine in Indonesia, drought and bush fires in the Galápagos Islands, rainstorms in California and South America, and the destruction of Peru's anchovy harvest and wildlife 1982–1983; and algal blooms in Australia's drought-stricken rivers and an unprecedented number of typhoons in Japan 1991.
El Nińo usually lasts for about 18 months duration but the 1990 occurrence was not fully spent 1994, the first time on record that it returned for a fourth consecutive year. The last prolonged El Nińo 1939–41 caused extensive drought and famine in Bengal.