Lesson From El Nino's Tantrum: Be Prepared
From Peru to Malibu, the weather pattern may cause $3billion in damage. But early warnings temper tolls.
The world's worst El Nio in 100 years is slowly releasing its grip on the earth's climate.Skip to next paragraph
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The phenomenon has left its calling card across the globe - from severe droughts in Indonesia and South Africa to floods of biblical proportions in Peru and China. Other impacts were more bizarre: On Feb. 5, El Nio whipped up global winds so fast that they slowed the earth's rotation by 0.6 milliseconds, making it the longest day of the year.
Overall, it could inflict as much as $30 billion in damage by the time it ends and is now blamed with causing more than 2,000 deaths. Yet for all the mischief and casualties, the toll could have been far worse. One of the legacies of what could become history's costliest weather tantrum is the preparations countries took to blunt its impact - something scientists are now hoping to build on to cope with future El Nios.
In northern Peru, for instance, the government led an effort to clear channels and drainage canals filled with debris. And in flint-dry southern Africa, farmers were encouraged to plant fewer crops to save water.
"We're learning how to cope with changes in climate," says Nicholas Graham, director of the International Research Institute's (IRI) experimental forecast division at the Scripps Institution of Oceanography in La Jolla, Calif. The IRI, based near New York, was established in 1995 to develop tools for generating region-specific forecasts of climate events, such as El Nio.
First recorded by the Spanish as they colonized the West Coast of South America, El Nio refers to the accumulation of unusually warm water off the coast of Peru every five or six years. But El Nio is only half of what scientists call El Nio-Southern Oscillation (ENSO), which includes the phenomenon's effect on the atmosphere.
Ordinarily, cold water wells up along the South American coast. Heated at the tropics, the surface water is blown eastward by the trade winds toward Indonesia. Over time, the warm water reaches Indonesia accumulates, then backs up toward the Central Pacific. As it does, warm moist air rises to form intense thunderstorms. These storms weaken, and in some cases, reverse the trade winds, allowing the warm water to continue moving back toward South America. There it builds off the Peruvian coast, drenching the country with rain that would normally pelt Indonesia. The intense convection that generates the thunderstorms also sets up a train of events in the atmosphere that can alter weather patterns worldwide.
The phenomenon is part of the climate's normal pattern of change, researchers say. And the damage that altered weather patterns inflict in some regions is offset by benefits in others. During an El Nio year, for example, hurricane activity in the Atlantic is suppressed.
Strong El Nio events such as this year's occur at intervals ranging from 15 to 60 years, according to Henry Diaz, a research meteorologist at the National Oceanic and Atmospheric Administration's (NOAA) Climate Diagnostic Center in Boulder, Colo. The ENSO of 1877-78 "was a very big event, equal to this one," he says.
Until the 1997-98 ENSO, however, this century's record went to the El Nio of '82-83. Damage estimates for that event range from $8 billion to $13 billion. It also provided the stimulus for forecasting research, which helped blunt the impact of this year's event.
Some of that help came from El Nio itself. Although ENSOs produce changes in regional weather patterns, "there are a lot of localized differences" within a region, says Tim Rocke, foreign-grains-production chairman for the US Department of Agriculture's Foreign Agricultural Service. In key agricultural areas that often feel El Nio's touch, it didn't have the impact many worried it might.
Last June, the USDA estimated Australia's wheat harvest at 16 million metric tons. This past January, he says, the estimate had risen to 19 million metric tons, the fifth-largest ever for Australia. Last August, Argentina's corn harvest looked as if it would reach 13 million metric tons. Last month, the USDA revised its estimate to 16.5 million metric tons. Meanwhile, India is poised for a record rice harvest.
El Nio "really hasn't affected the countries that feed the world," Mr. Rocke notes. Despite drier-than-normal conditions, he says, rain fell at critical times during the growing season.
In other areas, the preparations based on climate forecasts appear to have softened El Nio's impact.