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El Nino is the term used for the period
when sea surface temperatures are above normal off the South American coast
along the equatorial Pacific, sometimes called the Earth’s heartbeat, and is a
dramatic but mysterious climate system that periodically rages across the
Pacific. El Nino means "the little boy" or "the Christ child" in
Spanish, and is so called because its warm current is felt along coastal Peru
and Ecuador around Christmas. But the local warming is just part of an intricate
set of changes in the ocean and atmosphere across the tropical Pacific, which
covers a third of the Earth’s circumference. Its intensity is such that it
affects temperatures, storm tracks and rainfall around the world.
Droughts in Africa and Australia tropical storms in the Pacific,
torrential rains along the Californian coast and the Peruvian deserts have all
been ascribed to the whim of El Nino. This at least is the
theory, and it has worked pretty well over the past century, with El Nino
occurring about every three to five years and La Nina in between. But there have
been some baffling developments in recent years. For one thing, El Nino has
returned three times in the past four years. For another, since 1976 El Nino has
dominated relative to the cooler phase (La Nina). There has been only one
significant La Nina, but five El Ninos, including an extremely severe one in
1982—1983 that caused damage costing 8 billion dollars. Moreover a huge pool of
warm water has settled down near the dateline in the central Pacific.
Yet it is important to understand the changes if scientists are to be able
to forecast the climatic effects of El Ninos with any degree of accuracy. This
is not just an academic task— accurate forecasts can spell out feast or famine
in many tropical countries around the world. Forecasting efforts have focused on
El Nino, whose effects are generally more severe than those of La
Nina. A worrying possibility is that the changes maybe due to
greenhouse warming. If so, the recent fluctuations may be an early glimpse of
worse things to come. What can be the possible cause of the changes of El Nino