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Scientists find El Nino's grandparents

By Marsha Walton

During the cooler
During the cooler "La Vieja" pattern, anchovies rule.

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(CNN) -- Scientists say they have evidence of two alternating climate cycles, "El Viejo" (the old man) and "La Vieja" (the old woman) in the Pacific -- giving them a better understanding of climate changes around the globe. Their findings could impact everything from weather research to what toppings are available for pizzas.

While their impacts are not as dramatic as the well known "El Nino" effect, the "sardine regime" (El Viejo) and the "anchovy regime" (La Vieja) each lasts about 25 years in the world's biggest ocean.

"Everything in the Pacific is being affected," said Francisco Chavez of the Monterey Bay Aquarium Research Institute in California.

Recognizing El Nino

Since the dramatic weather events of 1997-98, "El Nino" became a household word. "El Ninos," which usually last just a couple of years, are a warming of waters in the central and east central Pacific. "La Nina" is a cooling of that same region. According to NOAA, the National Oceanic and Atmospheric Administration, both can affect patterns of rainfall from Indonesia to the west coast of South America—literally half the world.

The warm sardine regime looks like a mild El Nino, while the cool anchovy cycle is similar to a mild La Nina.

Studying records that go back to the late 1800s, Chavez and his colleagues report in this week's Science magazine that during the anchovy, or cooler phases, stronger ocean currents supply more nutrients to the eastern Pacific. That helps support large populations of anchovies, salmon, rockfish, and several types of seabirds.

During the warmer regime, sardines rule, with strong populations throughout the Pacific.

"We know that these cycles are related to changes in ocean circulation and atmospheric effects on the ocean, primarily by winds," said Chavez.

New explanations offered

These findings could provide a new explanation for some events of the past century.

Chavez recalled short supplies of sardines starting in the early 1950s. "The first reaction was that we had over-fished them," said Chavez.

Instead, it may have been the natural phenomenon of a temperature change that led to smaller catches, he said.

While only four of these cycles have been completed, the information could help make more accurate long-term climate predictions. The temperature fluctuations being studied are not dramatic: one degree, on average, is a lot of heat across such a huge body of water.

"We need to be careful when we make global warming predictions, because records could be biased by this cycle," said Chavez.

Further study needed

There's already evidence that the cooler "La Vieja" has kicked in over the past year. Right now there are big, healthy populations of salmon off the coast of Oregon, fitting with the beginning of an anchovy regime.

Chavez says further study could also help fishing fleets, and even governments consider economic changes tied to the climate fluctuations. This could be especially helpful to economies in developing countries, because they would have several years lead time in knowing what the ocean waters have in store for them.

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