Environment
Figuring Out El Nino
New Pacific Climate Condition Means Drought For Some Islands, Cyclones for Others
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At a November briefing in Honolulu, the U.S. National Weather Service brought together meteorologists, emergency management officials and media representatives to explain the state of Pacific weather prediction as the region goes into the so-called El Nino weather cycle.
El Nino, Spanish for “the child,” was named by fishermen on the Pacific coast of South America who noticed the periodic, extreme weather change that became obvious around Christmas time—which, of course, is the celebration of the Christ child’s birthday. Meteorologists actually call the cyclical weather event the “ENSO,” or El Nino Southern Oscillation. According to Jim Laver, director of the Climate Prediction Center in Washington, D.C., the last El Nino event in 1997, “was the mother of all El Ninos and people blamed just about everything on it.”
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As of now, Laver says, “a Pacific Basin-wide ENSO condition is in progress. This effects the jet stream and weather around the world.” Compared to 1997, Laver estimates that the current El Nino is “on the high end of moderate, or maybe the low end of high on a scale of severity.”
The El Nino condition is caused by the movement of warm, western and central Pacific waters in an easterly direction toward South America. “Think of it,” Laver said at the briefing, “as warm water sloshing around in a bath tub.” In this case, the warm water sloshes from west to east and may extend several hundred meters below the ocean surface. “The regions of warm water are like weather fronts, except they’re under water.” And, like weather fronts in the atmosphere, they move and circulate and change shape over time. For scientists, an El Nino event is defined as a condition where the warm water area is .5C above the average water temperature in the region for three consecutive months.
The regions of warm water produce changes above the ocean’s surface, too. “Warm water,” explains Guam NWS meteorologist Chip Guard, “creates updrafts of moist air which condense and create rain.” So the atmosphere above these areas of warm ocean water is also the place where storms are born. The warmer the water, the stronger the possibility of storm and cyclone generation.
El Nino on the Web
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El Nino is really a huge cyclical system of air, heat and moisture in motion. As the warm air continues to rise above the clouds it has created, it joins the jet stream where it travels for several hundred miles before cooling and dropping back down to sea level. Where the warm air descends, clear skies and, more ominously, the threat of drought are created.
Laver summarized what scientists predict is coming in this current El Nino cycle. “We expect it to be wet in the central and south Pacific. But in Australia, Indonesia and Hawaii, we expect it to be dry. And there will be a weakening of the normal trade winds.”
Guard points out that the El Nino pattern can sometimes persist for two years at a time. “The El Nino pattern is actually older than the islands themselves it’s something that has been going on for millions of years.” In this most recent cycle, he is most worried about tropical storms or cyclones hitting the Marshall Islands and the Samoas. “Coastal erosion is also going to be a real problem for small islands,” he adds. Flooding and mudslides are the other problems these storms create—as in the storm that hit Chuuk last summer killing 47 people, or the 1997 mudslides in Pohnpei that killed 19. El Nino years can drastically alter rainfall patterns in some places. “In Tarawa, Kiribati, for instance,” Guard says, “a normal year’s rainfall is about eight inches, but during El Nino years they get about 20 inches of rain.”
The Univerity of Hawaii’s Mike Hamnett, who, with Guard, has been active in consultations with the American-affiliated Islands, says that government planning and public education in these places has made many Island locations much better prepared for this latest El Nino event.
“Governments facing drought conditions have moved in reverse osmosis [desalinization] units and they are fixing leaking pipes in their water systems. Public education about water conservation has also reduced consumption.” Hamnett and Guard also point out that storms cause destruction of food crops and that, since tuna stocks move east with the warm water, income from fishing and processing is lost in Micronesia.
The El Nino pattern can cause a host of problems in the Pacific, but—with better research and prediction capabilities—many Island governments are better prepared for the 2002-2003 event than they ever have before.
