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El Niño

The 1997–98 El Niño. In this global view of the Pacific Ocean, the warmest waters are shown as white.El Niño is Spanish for "the child" and refers to the infant Jesus, because the occasional warming in the Pacific Ocean off South America peaks around Christmas time. Every 3-5 years, ocean currents in the Pacific Ocean are reversed. No one knows why this occurs. Warm water, which normally pools near Indonesia and the Philippines, moves eastwards towards northwestern South America. The event usually lasts up to a year, often starting in spring, climaxing in December and January, then easing off by May the following year. The storms that accompany the warming of the ocean waters also shift eastwards. This shift causes the weather to change all over the planet.

In normal conditions, the current flowing west away from the Peruvian coast (shown by the white arrows) causes cooler waters from...Read More >>In normal conditions, the current flowing west away from the Peruvian coast (shown by the white arrows) causes cooler waters from the depths to rise to the surface. This is called upwelling. The nutrient-rich waters attract abundant marine life. During an El Niño, the offshore current is reversed, preventing upwelling.

Effects of El Niño

The warmer than usual waters of the tropical Pacific Ocean off South America release so much energy into the atmosphere that weather patterns across the Earth are dramatically affected. Typhoons in some parts of the Pacific become more active, while rainfall is much higher in western South America.
Fish catches offshore in Peru and Ecuador are lower than normal because marine life, which is usually abundant due to the upwelling of cooler, nutrient-rich waters from the ocean depths, tends to migrate to colder waters either to the north or south. El Niño-caused droughts may affect southern Africa, India, Southeast Asia, Australia, the Pacific Islands and the Canadian prairies.

El Niño, originally El Niño de Navidad (the Christmas boy), was given this name by Peruvian fishermen in the 1600s. It was so called because its effects started to be felt around the end of December.

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