El Nino Called ‘Climatic Event Of Century’

There’s trouble in the air. Specifically, in the air off the west coast of the Americas, where the sea surface has been heated to abnormal extremes by an ominous, intermittent flood of hot water called El Nino.

The last time conditions looked like this was when the strongest, most destructive El Nino on record struck in 1982-83. By the time that event subsided, some 2,000 people had died in flooding, mudslides, droughts, fires and sundry related calamities, hundreds of thousands were forced out of their homes, and economic losses topped $8 billion worldwide - $1.5 billion in the United States.

This year’s version promises to approach or even equal 1982-83, which climate researcher James J. O’Brien of Florida State University’s Center for Ocean-Atmospheric Prediction Studies (COAPS) calls “the mother of all Los Ninos.” Already, El Nino has begun to have dramatic effects in some parts of the world and the U.N.-sponsored World Climate Research Programme warns it “could be the climatic event of the century.”

“This one leapt out of the starting blocks,” said Ants Leetmaa, director of the National Weather Service’s Climate Prediction Center. “By this summer it was ahead of all the others we’ve seen” since 1950 in terms of early and strong sea-surface warming.

Unlike 1982-83, the world has advance warning this time and the opportunity to protect itself. The threat of a repeat has prompted a rush of scientific symposiums, congressional hearings and anxious regional palavers from Zimbabwe to Australia to flood-leery California, where a federal-state “El Nino summit” has been scheduled for next month in Los Angeles.

“We’re preparing for the worst, but hoping for the best,” said Douglas P. Wheeler, California’s secretary for resources.

In addition, the likely ferocity of this year’s event has scientists wondering whether the frequency and intensity of El Nino episodes is suddenly on the rise - and what that might mean.

In many parts of the world, its effects began this summer. In Indonesia, where drought began weeks ago, one of the world’s largest coffee crops is endangered and dry conditions are aggravating fires in some of the planet’s last tropical rain forests. In the northern Philippines, farmers reportedly carried images of the infant Jesus into their fields, praying for rain that has been scarce since May.

In Chile, a coastal desert suddenly bloomed this year after dozens of inches of rain. In Peru, freak, heavy snowstorms have stranded travelers in the Andes. And for all of northwestern South America, there is almost certainly more to come. (During the 1982-83 episode, many parts of Ecuador and Peru got 100 inches of rainfall in six months, according to the U.S. National Oceanic and Atmospheric Administration.)

In parched Australia, where some ranchers reportedly are killing cattle they won’t be able to feed, the government estimates that the wheat crop will be 28 percent below normal. In Zimbabwe, experts have been meeting to plan a response to what is expected to be an uncommonly severe drought there and in South Africa. The last ENSO-related dry spell reduced Zimbabwe’s economy by 12 percent, according to one estimate.

Researchers also have found that, in general, an El Nino episode often tends to be followed by its La Nina opposite: a combination of abnormally cold surface water and abnormally high air pressure in the eastern Pacific, last seen in 1996.

Although the ENSO phenomenon predates by thousands of years the human carbon dioxide (CO2) pollution that now threatens to cause global warming by enhancing the “greenhouse” effect, some scientists worry that the frequency and severity of El Nino effects may have begun to change within the past two decades.

“We’ve had two “hundred-year’ events separated by only 15 years,” said Leetmaa, who cautions that it’s far too early to know whether that might simply be a statistical fluke.

So far, most climate experts would probably agree with marine physicist Tim Barnett of the Scripps Institution of Oceanography, who told a Sept. 11 House subcommittee hearing that the best models available show that “As you increase CO2 (in the atmosphere), you don’t see any increase in El Ninos.”

Others believe something odd may be going on. Kevin E. Trenberth, director of climate analysis at the National Center for Atmospheric Research, said “If one simply looks at what’s been happening in the tropical Pacific during the past 20 years, it’s very unusual.” Not only did it have “one of the biggest (El Nino events) on record,” but also “this peculiar event that lasted from 1990 to 1995 and is either the longest on record, or three separate events in a row.”

Trenberth also notes that there have been eight El Nino events but only three La Nina episodes in that period. By comparison, a study from COAPS shows that in the 53 years from 1944 to 1996, there were 27 neutral years, 15 cold or La Nina episodes, and 11 El Ninos. If that is something like a “normal” distribution (and it is impossible to know if it is, or even whether a typical pattern exists because the data cover too short a time span), then the past 20 years have had a disproportionate number of El Nino events.

These are not academic questions. After all, Leetmaa noted, most of the immigration boom into Sunbelt havens such as Arizona has taken place in the past 20 years. If that turns out to have been an unusually wet period due to frequent El Nino episodes, where will millions of residents get enough water when the climate turns back closer to the norm?

He and other ENSO veterans suspect it may take 10 or 15 more years of careful measurements to get answers to questions of that sort - if federal funding for the observation systems continues, which is by no means certain.

Around the world ENSOs are associated with upsurges of waterborne diseases such as hepatitis, dysentery, typhoid and cholera, as well as diseases carried by animals, including malaria, dengue, yellow fever, plague and hantavirus.