Not all ocean waters have a moderating effect on weather and climate. A massive ocean-atmosphere interaction in the tropical Pacific known as El Niño has brought about climatic devastation worldwide. The termEl Niño (Spanish for "the Christ Child") was coined more than a century ago by Peruvian and Ecuadorian fishermen who noted that in some years a warm ocean current appeared during the Christmas season and lasted for several months.

The strongest El Niño event of this century occurred from 1982 to 1983 and has been blamed for $8 billion in damage worldwide. Climatic effects of this El Niño included drought and brush fires in Australia, Indonesia, southern India, and parts of Africa and Brazil. In contrast, heavy rains fell along the equator, in Southern California, and the southeastern United States, while winter temperatures soared far above normal in the interior of Canada.

While scientists do not entirely understand the causes of El Niño, they believe that it is linked to dramatic atmospheric changes that typically occur over the North Pacific every 2 to 7 years. In normal years, prevailing winds blowing from the east help to push Earth's warmest ocean water into the western Pacific. For reasons that aren't clear, occasionally the prevailing winds weaken and the warm water begins to move eastward across the Pacific toward South America—starting El Niño.

El Niño's effects extend far beyond the South American coast. Storm systems that would normally have been kept farther west by the prevailing winds move into the central equatorial Pacific, bringing heavy rain to typically dry islands. These heavy storm systems further disrupt the normal flow of the jet streams across the Northern Hemisphere. In any El Niño year the polar jet stream shifts northward over western North America, resulting in mild winters over western Canada and the north central United States. At the same time the subtropical jet stream is more vigorous than normal, bringing heavy rainfall to the southern United States.

Source: MSP2. Oceans, Weather, and Climate. Retrieved from http://msteacher.org/epubs/science/science6/forecast.aspx on November 19, 2010.