Searching For El Nino

ARIZONANS BELIEVED THEY had a sighting last week, as the winds and rains of Hurricane Nora that had been pounding Mexico slammed into Yuma. Oystermen in southwest Canada have been claiming sightings since summer, when their nets brought up bivalves so riddled with bacteria thriving in the uncommonly warm water that the government halted the catch. Fishermen in Oregon are sure they've had a glimpse, too: tropical marlin are swimming into their nets. Southern Californians think they saw the quarry in a relentless invasion of Argentine ants. Los Angelenos saw it in the clear, almost smog-free summer they enjoyed this year. Indonesians are seeing it in the murk, as their necklace of islands chokes under a cloud of smoke blowing down from out-of-control forest fires. Late last week the poor visibility apparently caused the crash, in northern Sumatra, of an Indonesian Airbus flight from Jakarta, killing all 284 people aboard. A few hours later and 255 miles away, 29 seamen were reported missing in a collision between a supertanker and a cargo ship in thick smoke off the coast of Malaysia.

Looking for El Nino--the freakish, destructive disruption in worldwide weather--has become the meteorological equivalent of looking for Elvis, and sightings over the last two months have become about as frequent as sightings of The King. No wonder. The World Climate Research Programme of the United Nations predicts that the 1997-98 El Nino could be "the climatic event of the century," and climatologists warn that El Nino is already so extreme, and affecting so large an area in the Pacific Ocean off South America, that it could, as Nicholas Graham of Scripps Institution of Oceanography in La Jolla, Calif., says, "cause billions and billions in damage worldwide." This sense of impending doom has made everyone from emergency planning agencies to farmers desperate to spot El Nino's approach as early as possible.

But not every pompadour belongs to Presley, and not every piece of weird weather or bizarre animal behavior is evidence of El Nino. The Indonesian fires probably are. The Argentine ants and L.A.'s crystalline summer skies probably aren't; both arrived long before El Nino. Nora, bad oysters and tropical fish in northern waters--yellowtail tuna and mahi-mahi are being caught off Washington-might or might not be. (There is no evidence that El Nino, which is just a change in ocean currents, can warm up open-ocean waters over so much of the North Pacific this early in its cycle. Complicating matters more, a triangle of water from Vancouver Island to Hawaii to Baja California has been mysteriously warming for at least two years, long before this El Nino started.)

El Nino's effects are felt most directly near the equator; effects farther away usually do not take hold until winter. But while blaming every bit of weird weather on El Nino is excessive, there is no question that the current packs a wallop. The last big one, in 1982-83, killed more than 2,000 people worldwide, many in floods and landslides, and caused more than $13 billion in damage. How will this one compare? Chile is already reeling under its worst rainstorms in more than a decade; floods and landslides there have killed 18. people and displaced 60,000. And the rains have brought an explosion in the rat population; more than a dozen people have died from the hanta-virus the rodents carry.

El Nino is, strictly speaking, only the warm current of water that appears off Peru every two to seven years. Working out the "teleconnections" that explain how a tepid Pacific puddle will affect snowfall in Boston, winter rain in L.A. and wheat prospects in the Midwest is tricky. An El Nino begins when the trade winds that normally blow from east to west across the Pacific, along the equator from South America to Indonesia, slacken (map). No one knows why they diminish, though it may have to do with something as seemingly unrelated as snow cover in Tibet. In any case, these winds normally act like breezes in a tiny pond, piling up warm water in the western Pacific so that the sea surface there is as much as two feet higher and 15 degrees Fahrenheit warmer than it is at, say, Ecuador. But when the trade winds taper off, the warm water piled up at Indonesia sloshes back across the Pacific.

In weather terms, few things matter more than where warm ocean spots are. They provide the thermal energy that drives evaporation and hence cloud formation and storms. Now that the warm water has abandoned Indonesia, droughts have moved in. New Guinea and eastern Australia are currently bone dry. Indonesia's current dry spell has made crops fail and caused water shortages; 271 people, the government reported last week, have died of famine or of cholera blamed on the lack of clean water. The drought is also allowing forest fires, which are normally quenched by the monsoons, to burn out of control. The smoke is choking places as far away as Brunei, Thailand and the Philippines. New Guinea has had virtually no rain since May, and "is nearing a state of crisis," says meteorologist Marty Hoerling of the University of Colorado. Crops have failed and "depleted food stocks could be leading to famine."