El Niño more like Los Niños, weather study finds

The study's findings, published Friday in the journal Science, could help provide a few extra months of lead time. That's because the central Pacific warming starts its annual cycle slightly earlier than the eastern pattern. This would help the insurance industry, which now must lock in its annual rates before the Pacific activities become clear.

The scientists also found that the central Pacific warming events have increased in frequency over the last few decades: 80% of them in the last 60 years have occurred since 1990. At the same time, the eastern Pacific warming events have declined.

Nobody knows why, Webster said. It could be temporary, associated with natural oceanic or atmospheric oscillations, he added. But it is also possible that increasing sea surface temperatures associated with global warming may be causing the shift by triggering changes in trade-wind patterns.

"The nature of El Nino is changing, and there are lots of subtleties," Webster said. "We want to predict those variations in El Nino and work out what the implications are of this new type of Pacific Ocean warming."

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shara.yurkiewicz@latimes.com