Temperamental childrenOn March 24, 1989, the Exxon Valdez oil tanker hit a reef off the coast of Alaska and spilled a huge amount of crude oil into the sea. The accident happened because the ship had gone off course in an attempt to avoid icebergs. The flow was blocked because La Nina had caused the current to shift.
El Nino and La Nina are opposite phenomena ― in most cases the former is followed by the latter. When water temperatures in the eastern Pacific near the equator rise by more than 0.5 degrees for five months or longer, the phenomenon is called El Nino. When the temperatures decrease by 0.5 degrees, we get La Nina.
In Spanish, a “nino” is a little boy, often referring to the Christ child, and a “nina” is a little girl. Fishermen in Peru in the 19th century knew about El Nino. When the water temperature rose, their catch shrank.
El Nino was first scientifically defined in 1923 by the British mathematician Gilbert Thomas Walker. He collected 40 years’ worth of atmospheric data and found that the difference in air pressure between the south Pacific east of Tahiti and the Indian Ocean west of Darwin, Australia, fluctuated like a seesaw. When the air pressure in one area went up, it went down in the other. Walker called it the Southern Oscillation.
The Southern Oscillation and El Nino and La Nina are two sides of a coin. The Southern Oscillation is the fluctuation of air pressure and El Nino and La Nina are changes in the ocean temperatures. When the air pressure in the Indian Ocean goes up, El Nino starts. If trade winds strengthen, cold ocean water rises and the water temperature decreases, signs of La Nina. El Nino causes floods in Peru and Ecuador and droughts in Southeast Asia and Australia. La Nina brings rainy spells in Southeast Asia and dry periods in South America. As the World Meteorological Organization warned in July last year, La Nina causes atmospheric disasters in many places around the world. The WMO believes that the snowstorms that hit China late last month, a cold wave in Taiwan, India and Afghanistan, and floods in India and Sri Lanka, are associated with La Nina.
La Nina brings cold, dry weather to the Korean Peninsula. The Korea Meteorological Administration assumes that the two rounds of drastic temperature changes here this winter are related to La Nina. El Nino and La Nina appear once every two to seven years; their causes are unknown.
Some experts maintain that they are worsening due to global warming and causing more serious damage. If this is true, we humans are pushing ourselves into more trouble.
The writer is a JoongAng Ilbo reporter specializing in environmental issues.
By Kang Chan-soo [firstname.lastname@example.org]
with the Korea JoongAng Daily
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