The Subduction Crew

WHY SHOULD I CARE ABOUT “ENSO”?

by Homer Montgomery

0214 Z - R/V Melville, Southeast of Guam

With increasing frequency, ENSO is affecting our lives. ENSO is an acronym for El Niño Southern Oscillation. El Niño (“the Boy”) is named after the Peruvian Christmas festival for the Christ child. Every few years at this time the waters off the coast of Peru warm. Combining the traditional name and the meteorological term, you get ENSO. During this warm water event upwelling slows which means the fishing is not going to be good. Upwelling is important because it brings nutrients to the surface. Those nutrients kick off a process that produces abundant phytoplankton then zooplankton then fish then happy fishermen. In addition to lousy fishing during El Niño years, heavy rains fall in Central and South America. Floods and mudslides kill lots of people. On the other side of the Pacific, drought occurs in Australia. The monsoon rains in Indonesia are disrupted. Many other world-wide climate disruptions are produced by El Niño.

If El Niño is periodic, what is the other state when upwelling occurs off Peru, the fishing is good, and South America experiences doughts? What we have is an Anti-El Niño, if you will. Anti-El Niño was discussed by the acronym people but was rejected because it literally means the “Anti-Christ.” How about another catchy El Niño-like name? How about La Niña (the Girl)? We now have what is known as the El Niño-La Niña cycle.

I will bet everyone remembers the 1998 El Niño event if for no other reason than everything from headlines to bad jokes focused on the subject. Whatever went wrong, it must be El Niño. The perspective from this part of the Pacific was also bad. Australia had severe droughts although some nick of time rain saved some crops. Indonesia was burning with such thick smoke that an airliner crashed into a hillside because of poor visibility. Fires are set to clear land with the anticipation that the monsoons will put them out. The rains were late.

El Niño beings in the western Pacific as the first signs of a change are found here. A great pool of warm water is held in the Pacific by trade winds. As the trade winds weaken the vast pool of warm water flows to the east toward northern South America producing an El Niño event. Of particular note is a change in a measure called SOI which is based on the air pressure difference between Darwin in the Galapagos and Tahiti. A negative SOI means El Niño is going on and will continue. The other way around indicates a La Niña period. We are currently in a La Niña period for the 16th time this century.

The El Niño-La Niña cycle is an important one. Whether you choose to think about it or not, the cycle affects your life. If you lived in another place, say Australia or Peru, you would know all about the El Niño-La Niña cycle.

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