BY MERYL DAVIDS LANDAU

iller tornadoes in Florida. Precarious mudslides in California. Drought in Australia. Malaria in Brazil. Choking brushfires in Indonesia. Disastrous flooding in Peru. It's hard to believe that such disparate worldwide events can be traced to a singular phenomenon, but scientists say all were related to the extremely powerful El Niño of 1997-98. Though most of us never heard the term before 1997, the words for the quasi-periodic warming of eastern equatorial Pacific Ocean waters are now firmly ensconced in the popular lexicon. Now, as El Niño wanes and the world recovers from its consequences, scientists are busy assessing the impact and improving their predictions for its next debut-as well as for that of sibling La Niña, the term for when those same Pacific waters drop to below-normal temperatures. n With their expertise in such varied specialties as meteorology, marine life, and geology and geophysics, researchers at the Rosenstiel School of Marine and Atmospheric Science are helping to lead the world's quest for a better understanding of these phenomena. Since November of 1996 scientists began warning of the potentially serious weather consequences of the El Niño they had detected. During a strong El Niño, water surface temperatures in the eastern Pacific rise an average of four to six degrees Celsius, extending thousands of miles west from Central America. Initially, though, researchers didn't think this El Niño would be one for the record books. The seven computerized climate models used by meteorologists forecasted a normal event. The reason for uncertainties in the El Niño forecast? "The warming of the waters associated with an El Niño involves complex interactions between the atmosphere and the ocean," explains Bruce Albrecht, professor of meteorology and physical oceanography at the Rosenstiel School. "Some of these interactions are not well simulated by the models. The representation of clouds and their effects on El Niño is particularly troublesome. Over the warmest waters just north of the equator, cumulonimbus clouds (thunderstorms) heat the atmosphere and transport water evaporated from the ocean to higher levels in the atmosphere. Here water vapor can be transported thousands of miles to fuel storms that affect the United States. At the same time, extensive areas of shallow stratus clouds over the cooler waters of the eastern Pacific reduce the amount of energy from the sun that can warm the ocean surface. Unfortunately, the models used to predict the intensity of the El Niño can only make a very crude account of these cloud effects." mericans happily embraced the mild prediction in the summer and fall, and as the months passed by with few discernible effects, a barrage of 'El No-Show' jokes made their way to late night television. By winter, however, storms, floods, and droughts proved that El Niño was indeed strutting his stuff. In North America, February proved the cruelest month. The coast of California was battered by a powerful storm that brought 30-foot waves and endangered cliffside houses. Florida experienced killer freak tornadoes that usually don't hit south of Dorothy's Kansas. Massive flooding in Virginia turned canoes into more effective street transportation than Camrys. And in Canada, which saw unseasonable warmth, a huge storm that normally would have brought soft snow instead dropped rain that iced over powerlines and plunged four million residents into darkness. By this time, the rest of the world had met El Niño. Drought was so bad in Australia that cattle ranchers slaughtered thousands of their herd to forestall the animals' starvation. Ecuador, Peru, and Chile experienced merciless flooding. And fires blazed out of control in Southeast Asia with the absence of seasonal monsoons. What made this El Niño more perilous than most prior ones was that it was not only more powerful, but also longer lasting. "El Niños generally start in December," says Nelson Ehrhardt, professor of marine biology and fisheries at the Rosenstiel School. "But this one started in July, almost a half-year ahead, so the effects were very protracted." Ehrhardt and his colleagues traveled the globe to quantify El Niño's influence on the fishing economies of coastal countries. When the waters around Peru heated up, anchovies couldn't tolerate the warmer temperatures and quickly perished, collapsing the country's crucial fish meal industry. Off Chile, mature jack mackerels disappeared in record numbers, devastating the Chilean fishmeal industry. And many Central and South American countries saw their stocks of shrimp, algae, mussels, and other coast-clinging marine life destroyed. ow can one patch of heated ocean bring change to so many parts of the world? The answer is that water, wind, and temperature are linked in a complicated "global tango" that scientists have only recently begun to comprehend. In normal years, high pressure in the eastern Pacific sends equatorial trade winds blowing west. The winds push a fair amount of water with them, causing the Pacific to resemble a gradated swimming pool, with the deeper side near Indonesia and Australia and the shallower part on its eastern edge near Peru. El Niño's "dance" begins when the pressure drops and the trade winds ease. Without the winds, the warmer water that is usually pushed west begins to backslide eastward. This water overruns the cooler liquid ordinarily there, and surface water temperatures rise. The warmer water in the eastern Pacific also affects the atmosphere. The change in the wind and water patterns prevents the formation of the thunderclouds that usually bring heavy rain to the western Pacific, paving the way for drought, while the warmer water in the east brings about more evaporation and rain clouds, setting the stage for floods. At the same time, high air streams push over Central America toward Africa, sheering the tops off thunderclouds, climatologists say, and bringing about fewer Atlantic Ocean-based hurricanes during El Niño years. El Niño is also powerful enough to affect the narrow band of air flowing high over North America, known as the polar jet stream. During an El Niño cycle, a polar jet stream runs well north of normal, while a southern Pacific jet stream, the subtropical jet stream, is strengthened and push north from its normal position. It is the northern stream's northward displacement that kept Arctic air away from much of North America last winter. But by pushing the southern stream across vast expanses of warm ocean and the Gulf of Mexico, moisture and energy help fuel storms that make landfall over the southern states. But El Niño's dance cannot last forever. The extra ocean water pushing eastward is eventually deflected by the South American coast and heads northward, where it cools. The downward temperatures in the Pacific indicate that an El Niño is nearly spent. When El Niño will reappear is a question researchers are already asking with great interest. Some scientists believe that El Niño will return soon, due to the global warming now heating the atmosphere and, by extension, the Pacific. In the short term, all eyes are on La Niña, and the question of when the equally troublesome sister may come around. A strong El Niño usually portends a strong La Niña, climatologists say, and some believe the lower-than-normal Pacific temperatures may arrive as early as 1999. Like a yang to El Niño's yin, La Niña brings many of the reverse weather effects. "With the tops no longer sheered off the hurricanes and the southern jet stream not as strong, La Niñas are more favorable for hurricanes," Albrecht says. In fact, La Niña years are often worse for the United States, experts say. In addition to hurricanes in the Atlantic, the altered weather patterns typically bring tornadoes to the Midwest, severe winter storms to the Northwest, and droughts and forest fires to the Southeast. Rosenstiel scientists will be watching for La Niña, and for the El Niños to follow. A team from Miami plans to go out to the eastern Pacific within the next few years to take more specific temperature measurements from ships and aircraft, adding to an arsenal of data that already includes tracks from buoys in the ocean and satellites in space. Thanks to the researchers' efforts, the wide swath cut by El Niño and La Niña in the future may still keep the world on its toes, but hopefully never again catch it off its guard.

Meryl Davids Landau is a freelance writer living in Coral Springs, Florida. Illustration by Matsu. Photography by John Zillioux.

Miami magazine Home | Miami magazine Archive | Alumni Home | UM Home