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.”
On the other side of the Pacific, where a pool of warm water half again as big as the continental United States has settled, northern Chile has had a foot of rain this year. It is normally one of the world’s driest deserts. Santiago had more rain in June and July than it normally gets in an entire year. In Peru, snowstorms have blanketed the Andes, floods have washed through mountain towns and something close to hysteria is gripping the country.
But peripatetic oceanic hot spots do more than affect rainfall nearby. They also drive the world’s atmospheric circulation. So when the location of the warm pool changes, so does the weather in regions far removed from the tropical Pacific. “El Nino affects [other parts of the world],” says UC’s Hoerling. “But it needs a broker to do it. That broker is atmospheric circulation.” As winter approaches, the jet stream that blows across the Pacific from just off the China coast intensifies. El Nino shifts it north. One branch passes over northern British Columbia and never strays into the United States. As a result, fewer storms reach the American Northwest, northern plains, Ohio Valley, mid-Atlantic states and Northeast. All of these regions are expected to have a warmer-than-normal winter with below-average snowfall. The Great Lakes states could even bask in temps 5 degrees above the winter average. But the southern Rockies, especially the eastern face, may experience a dry winter with normal temperatures and a cool spring with high snowfall. Those who fancy spring skiing would do well to book Easter vacations in the Four Comers area.
The other branch of the jet stream is where things get really interesting. In an El Nino year, this “pineapple express” (so named because it starts near Hawaii) shoots across southern California and blasts through to Arizona, the .gulf states and out to the Carolinas. Winter in all of these places is expected to be wetter and colder than normal. Already the sloshing of warm Pacific water from near Indonesia to points east has shifted where tropical storms form. Rather than taking shape in the western Pacific, they are originating farther east, closer to California. In addition, the pineapple express funnels nascent storms toward the West Coast. California could get hit with 50 percent more tropical storms than usual. “Nora may be the first shot down this El Nino storm track,” says meteorologist Dan Cayan of Scripps. Although the fact that Nora formed was probably not due to El Nino, where it hit land may be. Scripps’s Graham calculates that California could get 50 to 100 percent more rain than normal this winter.
That’s what the state is bracing for. In L.A. County, fire stations have stockpiled a million sandbags and are holding tryouts for the elite, 48-member Swift Water Rescue Team. Other counties are holding emergency drills and clearing storm drains of debris, the better to move floodwaters to the ocean as quickly as possible. Cities are drawing up evacuation plans. Will it be enough? The project to build four- to eight-foot walls atop levees along portions of the L.A. River is only 30 percent complete. Some 14 cities and 500,000 people in the southeastern part of the county could face floods four to 10 feet deep. Malibu, the capital of natural disasters, is bracing for the mud and water that will cascade down the hills.
Next month the Federal Emergency Management Agency will convene an El Nino summit to discuss its possible impact throughout the United States. Such a discussion is unprecedented, made possible only because this is the first major El Nino predicted so far in advance. The National Oceanic and Atmospheric Administration issued its forecast last May, thanks to better data and better science: 70 buoys spread across almost one third of the globe in the tropical Pacific measure sea temperature and winds, and computer models of climate turn these readings into climatological predictions. With the 1982-85 El Nino, says Michael McFadden of NOAA, who is on his way to the eastern Pacific to make a service call to the buoys, “we didn’t even notice it until it was at its peak. That’s not an acceptable way to do business.” Now everyone has noticed El Nino. Some of the sightings are certainly mirages. But unlike Elvis, El Nino itself is definitely here.
THE WINDS OF CHANGE: HOW EL NINO WORKS
The chain of events leading to the unusual weather known as El Nino begins when the trade winds that usually blow across the Pacific from east to west diminish. As a result, the bulge of warm water that the winds keep bottled up near Indonesia slosh back toward South America. Through “teleconnections,” this movement of warm water affects weather worldwide.
1 Normal year: The trade winds blow from east to west, pulling warm water behind. El Nino year: The trade winds slacken, for largely mysterious reasons.
2 Normal year: Cold, nutrient-rich water wells up from below, supporting the Pacific food chain. El Nino year: Stationary warm water prevents up-welling. Fish stocks fall.
3 Normal year: A pool of warm water sits off Indonesia, bringing rains to the region. El Nino year: The warm water sloshes east, taking the storm clouds with it.
4 Normal year: The jet streams deliver rain to southern Mexico and the Pacific Northwest. El Nino year: The jet streams shift north, and so do the rains.
Below the surface. In El Nino years, the thermocline–the depth where warm surface water meets cold deep water–drops in the east. The cold, nutrient-filled water cannot rise, starving plankton and hence fish.
