For centuries, fishermen who have worked the waters off the
coast of Ecuador and Peru have known of a strange phenomenon that
causes the weather to shift wildly in the South Pacific.
Approximately once a year, primarily during December or January, the
abundant fish population that is normally found in the coastal waters
near these countries virtually disappears. The South American
fishermen gave this phenomenon -- marked by abnormally warm ocean
temperatures -- the name El Nino, which is Spanish for "TheChild,"
chosen because the weather change often arrives at Christmas time, the
celebration of the birth of the Christ Child.
While the various natural forces that create El Nino events were a
mystery for centuries, today scientists have a much greater
understanding of this powerful climatic phenomenon. In April of last
year, the National Oceanic and Atmospheric Administration (NOAA) moved
to enhance the United States' El Nino forecasting capability. NOAA
announced that it would provide $18 million over three years to
establish the International Research Institute (IRI), which is
dedicated to providing early warnings of El Nino and other climate
variability that influence drought, floods, and other destructive
weather patterns around the world.
Oceanic/Atmospheric Interplay
An El Nino is the result of a complex interplay of oceanic and
atmospheric forces. During an El Nino the dominant high- and
low-pressure centers in the southeastern and western tropical South
Pacific weaken, reducing the differnce in pressure between the two.
When pressure rises in the east, it usually falls in the west. In the
1960s, Dr. Jacob Berknes showed that the Southern Oscillation is
closely linked with El Nino, prompting scientists to name the suite of
changes associated with these phenomena the El Nino Southern
Oscillation (ENSO). The onset of ENSO sets off a chain reaction that
can dramatically affect weather patterns around the world.
Influencing Global Climate Change
While South American countries such as Peru can be dramatically
affected by an El Nino, scientists studying ENSO know that the
phenomenon has a much broader effect on weather throughout the world.
Today, ENSO is believed to be one of the most important factors that
influence the global climate.
ENSO has not only been associated with wiping out South American fish
harvest and other commercial fish populations, it has also been linked
to flooding and mud slides in southern California and other parts of
the world. It also has promoted droughts in Indonesia, Africa and
Australia. The world's leading hurricane forecaster, William Gray of
Colorado State University, bases his seasonal hurricane reports in
part on El Nino activity. Additionally, ENSO has been associated with
Indian and African Monsoons. And the extreme weather El Nino fosters
lead to conditions that spread serious, sometimes fatal diseases, such
as malaria, cholera and dengue fever.
EDITED 26-8-97: Ruby