|
By Henrylito D. Tacio, Special Correspondent
(First of two parts)
IT rose out of the tropical Pacific in late
1997, bearing more energy than a million Hiroshima bombs. By
the time it had run its course eight months later, the giant El Niño
had re-arranged weather patterns around the world, killed an
estimated 24,000 people, displaced six million more and affected
some 111 million folk on earth.
The estimated cost of property damage worldwide:
US$34 billion.
“The 1997-98 event was a wake-up call,”
recalls Michael Glantz of the National Center for Atmospheric
Research in Boulder, Colorado. “Awareness of what El Niño
can do to societies and economies is now high.”
No one knows precisely when El Niño first
struck. Historians date the phenomenon at least as far back as
the early 1500s, when Spanish conquistadores entered South America
amid raging storms. Some 400 years before that, there were
some records of terrible typhoons sweeping through pre-Columbian
communities.
Spanish fishermen named the event originally as
Corriente del Niño. The word corriente describes the periodic
appearance of warm ocean current in the eastern equatorial Pacific
region along the South American coasts.
The “Niño” word was traditionally
associated with the birth of Baby Jesus, as the phenomenon was
observed around Christmas, along the coasts of Peru and Ecuador.
Through the years, corriente was dropped out, leaving only “El Niño.”
Power unleashed
According to the Global Environment Outlook 2000
(GEO 2000), El Niños are not natural disasters but natural
variations in climate. They normally occur every three to five
years, lasting six to 18 months. Between El Niños, there are
often periods marked by a cooling of the surface waters of the same
area of the Pacific, a phenomenon called La Niña. The whole
cycle is called the El Niño Southern Oscillation.
The ocean current is characterized as a
mysterious, massive pond of warm, nutrient-poor seawater, which
produces a periodic shift in ocean temperatures and atmospheric
conditions in the tropical Pacific.
El Niño varies the surface temperature of the
central/eastern part of the tropical Pacific by up to 4 degrees
Centigrade, with associated changes in wind and rainfall patterns.
This condition disrupts weather around the world, leading to nasty
extremes.
The energy reserve El Niño carries is vast,
almost unimaginable. Accounts say that, “it contains more
energy than has been procured from all the fossil fuels burned in
the United States since the beginning of the century — that’s
all the gasoline in all the cars, the coal in all the power plants,
the natural gas in all the furnaces. It would take more than a
million large power plants, at 1,000 megawatts each, running full
tilt for a year, to heat the ocean that much.”
Far-reaching effects
“El Niños have far-reaching effects,” says
GEO 2000, published by the UN Environment Program. “The build up
of warm water along the west coast of South America prevents the
normal upwelling of cold water from the ocean depths. In the
western Pacific, the normally rain-bearing cloud systems shift
eastward, bringing heavy rainfall to this area while countries in
the western Pacific, such as Australia, Indonesia and Papua New
Guinea experience drought.”
Scientists say the effects of the changes in
wind speed and direction, sea surface temperatures and the depths of
the warm water often extend into temperate latitudes. For
instance, most El Niño winters are mild over western Canada and
parts of the northern United States, and wet over the southern
United States from California to Florida. Southern China is
subject to storms and southern Africa has a tendency to drought.
One of the most significant El Niño occurrences
happened in 1982-83. “This Niño was a maverick: It behaved
differently from recent predecessors,” recalls Dr. Eugene M.
Rasmusson, a diagnostic expert for the US National Oceanic and
Atmospheric Administration and a leading authority on the subject.
“That’s one reason we didn’t recognize it. Another
reason was a trick of nature. When it was first stirring in
spring of 1982, the Mexican volcano El Chichon belched an immense
volume of dust into the atmosphere. The alien material misled our
satellite sensors, thereby producing unreliable Pacific Ocean
temperature readings.”
Lessons
When the said El Niño arrived, it was totally
devastating. “The pressure anomaly registered the strongest
ever,” Dr. Rasmusson notes. “The trade winds faltered, and
the equatorial current reversed direction across the entire Pacific.
Sea-surface temperatures rose above normal, until a great tongue of
warm water stretched 8,000 miles along the Equator.”
But the 1997-98 El Niño was one of the
strongest on record, developing more quickly and with higher
temperature hikes than ever recorded. The episode developed
rapidly throughout the central and eastern tropical Pacific Ocean in
April-May 1997. During the second half of the year, it became
more intense than the major El Niño of 1982-83, with sea-surface
temperature anomalies across the central and eastern Pacific of two
to five degrees Centigrade above normal.
“The 1997-98 El Niño was the first to have
been widely predicted, thanks to the comprehensive El Niño
observing network which now spans the Pacific Ocean, and a network
of observational satellites,” GEO 2000 reports. “The
former includes ships, drifting buoys and sea-level gauges on many
Pacific islands, all relaying their observations to meteorological
centers in real time. In addition, several satellites measure
the temperature and elevation of the sea surface.” 
Next: Coping With El Niño
|
