By Sid Perkins
A refined model can foresee the onset of the climate-altering phenomenon known as El Niño as much as 2 years ahead of time, scientists say. Because a strong El Niño can wreak damage costing billions of dollars, such advance notice could prove extremely valuable.
Under normal circumstances, winds carry warm surface waters westward across the tropical Pacific. During an El Niño, however, these winds diminish or reverse direction, and the warm waters of the western Pacific spill eastward. During a strong El Niño, sea-surface temperatures along the equator then remain abnormally warm for several months, and weather patterns shift. The southwestern United States and Peru, for example, get more precipitation than normal, but Australia and Indonesia receive lower-than-average rainfall.