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How El Nino Works

        Science | Storms

El Nino Events
In 1997, Indonesian children walked through smoke as wildfires brought on by El Nino raged across the country.
In 1997, Indonesian children walked through smoke as wildfires brought on by El Nino raged across the country.
Thierry Falise/LightRocket via Getty Images

From 1950 to 2015, Earth has experienced 24 El Nino events [source: National Weather Service]. Some were stronger than others; it all just depended on how long and how much the eastern Pacific heated up. Two winters, 1982-1983 and 1997-1998, stand out as particularly strong, but 2015-2016 might end up the most powerful yet.

In 1982, El Nino wasn't the household word that it is today. Even some meteorologists had never heard of the term. So when an El Nino sent temperatures in the cool eastern Pacific to unusually high levels, scientists initially blamed the event on the recent eruption of Mexico's El Chichon volcano. By spring 1983 the water temperature had begun to return to normal and meteorologists decided it wasn't the volcano after all [source: Williams]. One thing was clear, though: This was the worst El Nino in at least a century if not longer. Drought dominated Australia, Africa and Indonesia, while some areas of Peru that normally received just 6 inches of rain (15 centimeters) were doused with 11 feet (3 meters)! In the end the climate event was blamed for $8 billion in damage and between 1,300 and 2,000 deaths [source: Gannon].

A monster El Nino reared its head again beginning in 1997. As the Pacific waters warmed, more than 24 million acres (9.7 million hectares) of parched Indonesian rainforest burned largely unchecked [source: Tacconi]. In Peru, heavy rains created ideal conditions for mosquitoes, and malaria infections increased threefold as a result. This El Nino, which released more energy than 1 million Hiroshima bombs during its eight-month reign, ultimately caused some $33 billion in damages and killed about 2,100 people [source: Suplee].

Yet another strong El Nino took hold during the winter of 2015-2016. By February, ocean temperatures along the equator in the eastern Pacific had been at or above record-high readings for several months, meaning it was probably even stronger than the 1982 or 1997 events. Still, those earlier El Ninos brought way more rain to southern California than anything the region saw in 2015 or early 2016. For reasons that aren't yet clear, this massive El Nino just didn't change the jet stream in the same way it had in the past. Instead, northern California and the Pacific Northwest caught the brunt of the precipitation [source: Swain].


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