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Their interest is twofold. First they want to better understand El Nino itself--what makes it work, what makes it recur, how it affects human activities. To that end, the National Oceanic and Atmospheric Administration (NOAA) announced last week that it is setting aside $2.1 million to study the impact of the latest flurry of El Nino-related storms.
At the same time, El Nino gives scientists a rare chance to study a phenomenon that transcends the short-term weather forecasts that are the bread and butter of meteorologists. In many ways, El Nino may be a dry run for the kind of large-scale weather effects some scientists predict will accompany the climate changes caused by global warming.
Like global warming, El Nino--or rather, the climate cycle that produces El Nino--does not generate weather per se: rather it alters the context in which weather takes place. The distinction here is a critical one. "Climate," as social scientist Michael Glantz, formerly of the National Center for Atmospheric Research, likes to say, "is what you expect. Weather is what you get."
Sometimes there can be a wide gulf between the two. In Australia, for example, El Nino caused extremely dry conditions that for a while last year had farmers contemplating suicide. But as it turns out, some rain did fall--just in time to rescue the wheat harvest from disaster. Does that mean the drought predictions were wrong? Not at all, says Nicholas Graham, a climate modeler at the University of California at San Diego's Scripps Institution of Oceanography. Think of what El Nino does as the equivalent of rigging a roulette wheel so that it comes up black 40% of the time and red 60% of the time, Graham suggests. "Just because it comes up black once," he says, "you don't conclude the roulette wheel isn't rigged."
In fact, this El Nino has showcased the progress climatologists have made over the past 15 years in understanding the earth's climate machine and the forces that drive it. In 1997, as soon as climate modelers spotted the area of warm water forming in the Pacific, they launched a coordinated effort to predict its effects on various regions of the world. Organized by the new International Research Institute for Climate Prediction--a joint venture of Columbia University's Lamont-Doherty Earth Observatory, the Scripps Institution of Oceanography and NOAA--these efforts have, in the main, been on target.
Scientists predicted, for example, that in western North America the south should be colder and wetter than last winter, while the north would be warmer and drier. That's just what happened: at one point this winter, it was snowing in Guadalajara, Mexico, while thermometers in Saskatchewan registered in the 50s. That doesn't mean the scientists are always right, of course. They can make broad-brush predictions of El Nino's effects without being able to forecast exactly what will happen in any given place. Some of the early prediction scenarios--no snow for the Olympic Winter Games at Nagano and monsoon failure in India--never materialized.