Typical pattern of sea-surface temperatures an during El Niño event.

EL NIÑO

• El Niño is a global climatic anomaly caused by a weakening of the trade winds along the tropical Pacific, which leads to warmer-than-normal sea-surface waters along the eastern tropical Pacific.

• The name of El Niño originated with Peruvian fishermen, who noticed that reduced fisheries were associated with the warmer-than-normal waters. The phenomenon tended to peak around Christmas; thus, they named it "El Niño," for "The Child Jesus."

• The root cause of El Niño is not known with certainty. Atmospheric scientists attribute it to the large-scale teleconnections emanating from the warm-water regions of the mid-Pacific along the equator.