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What Is El Niño?

El Niño has arrived with all the fire and fury that Mother Nature can muster. Scientists tell us that one of the strongest El Niño events on record has taken hold of the world's weather.

But what exactly does that mean? And in the rush to blame every dip in temperature and increase in rainfall on this global event, what can truly be traced to El Niño?

The climactic event known as El Niño, Spanish for "little child," has its origins in the Pacific Ocean. In a normal year, warm trade winds blow westward, warming ocean waters near Australia and Southeast Asia and cooling waters off the coasts of North and South America.

In an El Niño year, those westward trade winds weaken, and the pattern reverses itself. Cooler waters can be found in Asia, and warmer waters off the coasts of the Americas.

Because cooler water is nutrient-rich and warmer water isn't, the warmer ocean temperatures mean fish populations in the eastern Pacific dwindle.

On a global scale, the shift in oceanic temperature sets off a worldwide domino effect of erratic weather events.

Warmer waters along the western coasts of North and South America cause heavy rains in the typically arid coastal climates. Meanwhile Southeast Asia can expect drier than normal conditions throughout its monsoon season.

The East Coast of the United States can expect a warm winter and a mild hurricane season. In a strong El Niño year like we're having now, Asia and Africa can expect drier than normal conditions.

The strongest El Niños this century occurred in the 1920s and early 1980s. This year's El Niño has the potential to become the strongest yet. While it's difficult for meteorologists to know specifically which weather events occur as a result of El Niño, you can bet that long-term patterns of erratic weather can be traced to it.

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