Nations Prep for Strongest El Nino of This Century
BOSTON — From the frenzied trading pits at Chicago's Board of Trade to flood-ravaged Europe and the fire-blackened slopes of the Peruvian Andes, the world is feeling the wake-up stretch of the tropical Pacific's "little child," El Nino.
And scientists are warning that it may emerge as the strongest El Nino of the century.
Unlike past El Ninos, however, climate forecasters saw this one's rising well ahead of time, allowing countries to begin preparing for the dramatic weather changes El Nino brings.
In Peru, the government recently closed its anchovy fishery to ensure that a sufficient number of fish survive to rebuild the fishery after El Nino passes. Officials have stockpiled fuel and food in regions hardest hit by El Nino in 1982-83, increased the country's disaster budget, and even moved families out of flood-prone areas. In California, officials statewide are inspecting everything from pier pilings to water diversion channels to prepare for what forecasters say will be a heavier-than-normal rainy season.
As their tools and techniques improve, researchers say they hope to turn this year's general "it's coming" into accurate forecasts of El Nino's intensity and even of its impact on crop yields or river flows in specific regions.
The goal of such forecasts is to avoid a repeat of the disastrous 1982-83 El Nino. That event "had huge economic consequences," says Nicholas Graham, a climate researcher at the Scripps Institution of Oceanography, University of California in San Diego.
In developing countries, the floods, drought, and crop damage that year's event brought not only were costly, he says, but prompted large numbers of people to move from stricken rural areas into already overcrowded cities.
Already this year, wheat, soy bean, and cocoa prices are climbing in anticipation of El Nino's peak impact on regions that grow those crops.
But the early notice of El Nino's advance gives emergency planners time to prepare. This week in Harare, Zimbabwe, meteorologists are meeting with officials from countries in southern Africa to lay out the latest forecast and plan responses.
For all the preparations, however, El Nino still has an ability to humble forecasters. Although the first warnings of El Nino's onset came as early as last December and January, "nobody was ready for the severity of this event," says Dr. Graham. "It caught us by surprise and left us a little chagrined." This year's El Nino is shaping up to be stronger than even the 1982-83 event.
El Nino, known formally as El Nino-Southern Oscillation (ENSO), is the tropical Pacific's way to avoid overheating, according to David Battisti, professor of atmospheric science at the University of Washington in Seattle.
Cold seawater welling up to the surface along the South American coast heats under a tropical sun as the trade winds blow the water from east to west. A pool of warmed water piles up against Indonesia, then expands eastward back into the central Pacific, creating a vast regional hot spot. The warm, moist air rises, forming heavy thunderstorms. The storm activity weakens, and in some cases reverses, the trade winds, allowing the pile of warm water to slowly "slosh" back against South America. Meanwhile, the concentrated area of storms also affects larger-scale weather features to the north and south of the equator, altering weather patterns worldwide.
Of course, not all of El Nino's effects are negative. During the next year, Los Angeles may have the clearest air in decades. The flow of warm water north is why surfers off San Francisco this summer are riding the waves without wet suits and anglers are catching marlin and other fish rarely found in waters so far north.
TO improve their forecasts, scientists are looking for ways to link the global-scale climate models that can predict El Nino's onset to more-localized weather, crop-yield, and water-resource forecast models, according to Stephen Zebiak, a climate scientist with the recently formed International Research Institute for climate prediction, at Columbia University in New York. The institute is developing new forecast tools, as well as programs to help resource planners use the IRI's forecasts.
Four years ago, Graham and Scripps colleague Tim Barnett used an experimental model to help the Brazilian city of Fortaleza avoid a disastrous shortfall of water. Graham says planners decided to build a canal to bring water to the city based on the model's forecast that a drought in the region would continue - and it paid off.
Climatologists also are trying to improve the lead time for accurate forecasts. "The forecasts in December and January saw this [El Nino] as a normal-magnitude event," Dr. Zebiak says, adding that the true magnitude of the El Nino became apparent only in forecasts four months later.