We’ve all seen the images. Monsoons and floods and fierce winds that claim hundreds of lives and destroy thousands of homes — the disastrous legacy of El Niño.
But scientists around the world are collecting evidence showing that what we see is only a small part of what we get. Like the tip of the proverbial iceberg, the atmospheric disruptions brought on by the periodic warming of the waters of the central Pacific Ocean bring far more serious consequences than what we see on the surface.
Feared for decades by fishermen of Peru because of its devastating impact on fish populations along their coast, El Niño escaped close scrutiny by scientists until relatively recently. But in 1982-83 an estimated 85 percent of the sea birds in Peru were killed and horrendous storms raged along the coast of California — that really caught their attention.
That was followed by several lesser El Niño events, which occur every 3.7 years, but the 1997-98 El Niño moved the phenomenon onto center stage. Scientists knew well in advance that it was coming, and that it would be really big. Their research, much of which is still being analyzed, has led to some startling conclusions.
Scientists at several institutions, including Cornell University, have uncovered compelling evidence that the number of cholera cases in Bangladesh rises dramatically almost precisely 11 months after the waters of the equatorial Pacific begin to warm thousands of miles away.
Experts have long suspected they would find some upsurge in cholera because warmer waters enhance the growth of a pathogenic microorganism, Vibrio cholerae, that carries the disease. One of the leaders in the field is Rita Colwell, professor of cell and molecular biology at the University of Maryland and director of the National Science Foundation.
But a direct connection eluded them until the researchers came across a hospital in Bangladesh, one of the poorest and most densely populated nations on the planet, that had tested all incoming patients for cholera since January of 1980. That was just the data needed by Stephen P. Ellner, a biomathematician at Cornell.
Ellner created a computer model, into which he pumped all kinds of data, such as flooding from the snowmelt in the Himalayas, to see if a pattern emerged that could be linked to El Niño. What they found was quite startling. The number of cholera cases at the hospital peaked every 3.7 years, exactly the same frequency as the occurrences of El Niño.
But there was a twist. The peaks came 11 months after the beginning of the El Niño.
Further research offered tantalizing clues. It takes six months for the warmer waters to reach the shores of Bangladesh, and it takes another five months for the population of the deadly microorganisms to peak in the warmer waters. Bingo. That’s 11 months, matching the increase in the level of the disease precisely with the beginning of the El Niño.
As the researchers themselves point out, that’s only one test, and similar results will have to be found in other areas before the findings can be fully embraced by the scientific community. But it suggests very strongly that there is a link between El Niño and cholera, making the phenomenon far more deadly than had been thought.
The finding is particularly disturbing because many scientists believe El Niño’s intensity will get even worse if the planet continues its current warming trend.
Problems Pile On