El Niño is an abnormal warming of the ocean's surface.
It's caused by an unusually warm current flowing eastward across
the Pacific Ocean. Because the Pacific is so large, this current
is huge too. Sometimes, in fact, it's wider than the U.S.!
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These computer
images show the Pacific Ocean during normal conditions
(above) and an El Niño event (below). North America
appears in dark brown in the upper right corner of each
picture.
Source: NOAA: El Niño
Theme Page
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This surge of warm water has a tremendous impact. The extra
heat within the water interacts with the atmosphere
above, shaking up weather patterns. Dry places get drenched,
and wet places turn arid.
These dramatic changes can cause significant health and environmental
effects.
click
to enlarge image  |
Red,
orange, and yellow represent areas that experience unusually
warm winters during an El Niño event.
Source: NOAA:
El Niño Theme Page
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Written records about El Niño date back to 1525, and
geological evidence shows that the phenomenon is at least 13,000
years old. Yet El Niño didn't attract serious scientific
attention until about 30 years ago.
SOMETHING STRANGE IN SOUTH AMERICA
In the 1970s, fishermen found that their catches off the west
coast of South America had turned from great to bad. This seemed
to occur every few years around Christmas, so the fishermen
connected it with the birth of Christ. They named the event
El Niño ("little boy" in Spanish). El Niño's full
name is El Niño Southern Oscillation (ENSO).
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Scientists
say the 1982-83 El Niño event may have been the
worst in history. Red and orange show where the ocean
turned abnormally warm.
Source: NOAA
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Things heated up in 1982-83. Peru's rainfall nearly doubled.
The southwestern United States also got far more rain than usual.
The extra moisture meant more plants. That, in turn, meant more
food for mice and rats—plus outbreaks
of disease carried by the rodents. At the same time, droughts,
dust storms, and forest fires swept ordinarily wet Northern
Australia, Indonesia, and parts of Africa. Altogether, El Niño
was blamed for 2,000 deaths and $13 billion in losses worldwide.
Many factors in the ocean and atmosphere combine to cause El
Niño. It seems to be
coming more frequently, which has
climate experts worried.
You can learn more about El Niño from the National
Oceanic and Atmospheric Administration.
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El Niño is the best model we have of
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