WEATHERING EL NIÑO
March 2, 1998
This winter's freakish weather problems are being blamed on the El Niño but is the El Niño really at fault? NewsHour correspondant Jeffrey Kaye speaks with weather experts who say that the El Niño is not causing this winter's storms, only intensifying them. The experts explain what an El Niño is, how it is affecting our weather and world, and what we can expect in the future.
JEFFREY KAYE: This winter's crop of storms in California and in Florida have taken on mythic proportions with the advent of El Niño. California has had twice its normal rainfall. Last week, rains flooded parts of Northern California. To the South, mudslides claimed two lives and rushing waters wiped out roads. In Central Florida, tornadoes ripped into communities with deadly fury. Climatologist Tim Barnett says El Niño is often misunderstood. Barnett, who is with the Scripps Institution of Oceanography in San Diego, says El Niño doesn't cause storms but it does steer and intensify them.
TIM BARNETT, Scripps Institute of Oceanography: There are storms every year, whether there's an El Niño or no El Niño, isn't there? What the El Niño can do is enhance storms, or change the places where they occur and where they have their biggest impact.
JEFFREY KAYE: The term El Niño refers to a warming of the Pacific Ocean every two to seven years but as the last big 1983 El Niño demonstrated with storms and droughts around the world, El Niño's reach is international.
TIM BARNETT: El Niño is best thought of as a short-term change in the global climate. It's a background under which the storms are generated. It's the background that helps steer them and direct them as to where they're going to be.
JEFFREY KAYE: El Niño involves a complex interplay between the atmosphere and the ocean.
TIM BARNETT: Normally, the warmest part of the world ocean is over here. And during an El Niño and particularly this El Niño, the warmest water on the planet shifted out into this region, and it's that warm water that really drives the atmosphere.
JEFFREY KAYE: How so?
TIM BARNETT: Heats it from beneath.
JEFFREY KAYE: In normal years trade winds blow from the East along the equator, piling warm water in the Western Pacific. The ocean heats the atmosphere, creating clusters of thunderstorms.
TIM BARNETT: Now, during an El Niño year these winds relax, and in some cases this year for a couple of months in the summer they actually reversed, rather than blowing this way over in this part of the world, they were actually blowing this way.
JEFFREY KAYE: And so the massive pool of heated water usually in the Western Pacific shifted East, along with its thunderstorm clusters, towards North and South America.
TIM BARNETT: The warmest waters in the ocean are no longer found here in the Indonesian region but are now found out by the dateline, or even further East, as it was this year.
JEFFREY KAYE: So just about everything that normally happens, happens further East?
TIM BARNETT: Yes. In the tropics.
JEFFREY KAYE: So this year, warmer than normal waters off the California Coast produced a bounty for sports fishing. Warm water fish, such as Yellow Fin Tuna and Yellowtail, migrated hundreds of miles North. And the heavy storms that normally fall over East Asia also move to California.
RHEINHARD FLICK, Scripps Institute of Oceanography: It's hard to imagine now, but, of course, up until last fall there was a beach here fifty to a hundred feet wide.
JEFFREY KAYE: Oceanographer Rheinhard Flick, also of Scripps, says El Niño generated storms, stripped the sand of many California beaches.
RHEINHARD FLICK: Because of the wave action and the water turbulence, essentially sucked out the fill from underneath the foundations, and then caused the foundations to settle and collapse.
JEFFREY KAYE: A number of beach homes in Delmar, just North of San Diego, were wrecked, testimony to the storm's intensity. Flick says the storms, along with ocean warming and low pressure, have raised sea levels along the West Coast by almost a foot. In addition, El Niño's pressure system and jet stream winds have steered the storms further South than normal. The waves they've generated have been choppier than usual and more hazardous.
RHEINHARD FLICK: Depending on exactly the location on the coastline, many areas along the coast are more vulnerable. In other words, exactly how the waves propagate, exactly how they move through the area between the offshore islands and the coastline is highly dependent on exactly which direction they come in.
JEFFREY KAYE: Humans are not the only animals facing El Niño-related problems. The Marine Mammal Care Center in San Pedro, South of Los Angeles, has taken in record numbers of stranded and injured seals and sea lions. Jackie Ott, the center's director, calls them "El Niño babies."
JACKIE OTT, Marine Mammal Care Center: We can make a couple of assumptions. They aren't able to swim in the heavy surf caused by the recent storms, and possibly they were still dependent on their mother. She has gone to colder waters to find the available food source, which is fish.
JEFFREY KAYE: Why did the fish move to colder waters?
JACKIE OTT: The fish are moving to colder waters after their food sources, so El Niño has disrupted the whole balance of the natural food chain in this area.
JEFFREY KAYE: At the bottom of the marine food chain a microscopic phytoplankton that normally thrive in the up-welling of colder water.
TIM BARNETT: The phytoplankton are fed on by zooplankton, which are little animals, again very small, but the zooplankton are the basic food for things like anchovies and sardines. And, you know, it goes on up the food chain from there. So if you cut the legs off the food chain, so to speak, by stopping that up-well and bringing that warm water in, no phytoplankton or reduced phytoplankton. There are going to be less zooplankton. That means less food for anchovies and sardines and such. And what eats the anchovies and sardines? Seals.
JEFFREY KAYE: Another El Niño-induced chain reaction is disrupting global weather patterns.
TIM BARNETT: Tornadoes in Florida, that was bizarre. I think that's happened very seldom in February. The storm was on a much more southerly track than it would normally have been. And that's what we've been seeing coming through California, down across Southern--Southwest, hitting Texas, pulling up moist air from the Gulf of Mexico, and then smashing the Southeast. That's not the normal storm track. So in the sense that you say El Niño moved the storm track into that position, you could blame it on El Niño.
JEFFREY KAYE: This winter hurricanes hit Baja, California, and the Southwest United States.
TIM BARNETT: If memory is correct, we've had eight landfalls of hurricanes since the turn of the century into the Southwest. Seven of those eight occurred during El Niño years.
JEFFREY KAYE: And the reason for that?
TIM BARNETT: The water along Central America and up along the Baja was just a lot warmer this year, five or six degrees Fahrenheit warmer, and, as you know, El Niño's need--I mean, hurricanes need warm to survive.
JEFFREY KAYE: Other dramatic weather phenomena have similar explanations. Indonesia experienced massive fires as a result of drought. The reason: Normal rainfall moved thousands of miles to the East to, in some cases, South America. This winter's torrential rains in Peru have caused more than 200 deaths--victims of mudslides and massive flooding after rivers overflowed their banks. All these weather patterns are for the most part textbook consequences of El Niño, according to Tim Barnett. But Barnett says there's much about the phenomenon scientists don't understand, such as how it starts.
TIM BARNETT: We know that the distribution of sea surface temperatures in the tropics affects the winds. We also know that the winds drive the oceans and change the sea surface temperature. So if you change the winds, you know you'll change the ocean temperatures, or if you change the ocean temperatures, you know you're going to change the winds. So it really is a chicken and egg. There's no beginning, no end to this kind of a thing. There may be triggers that kick it off or start to energize the cycle, and there are probably at least three possibilities there, none of them known for sure, all controversial. The amazing thing is, in spite of the fact that we may not be able to know exactly what triggers say this event, we can still predict it pretty well.
JEFFREY KAYE: Barnett says this El Niño, which took more than a year to build up, should peter out over the next couple of months. By fall, scientists are predicting La Nina. The effects will be a reversal of El Niño conditions, with colder than normal Pacific Ocean temperatures. Where it's rainy now, it should be dry. Areas of drought should expect rain.