September has been a strange month for folks who live beside the Pacific Ocean. In the normally chilly waters off Northern California, fishermen are reeling in tropical fish! Surfers find that the water is so warm, they don't need wet suits. Thousands of pelicans, which belong in Peru, have shown up in Chile, where the weather has been weirdly wet.
What's happening? For months, a climate shift called El Niño (el nee-nyo) has taken hold of the Pacific, warming waters, sending fish and birds to the wrong places and brewing terrible storms. El Niño comes along every few years, but this year's may be the most powerful of the century. It threatens to turn the world's weather topsy-turvy this winter.
What Is El Niño?
El Niño is a natural weather cycle that disrupts the way winds
and ocean currents travel across the Pacific. Normally, belts of wind called trade winds blow from east to west across the ocean. These winds send storms toward Asia and push cool water to the eastern Pacific.
El Niño occurs when the trade winds weaken and currents reverse direction. Water in the eastern Pacific warms up. The warm water releases extra heat and moisture into the atmosphere. This has a huge effect on weather around the world.
Until recently, El Niños arrived two to seven years apart. But lately they have been appearing more often. Scientists are puzzled. Is this just a natural change in the climate? Or could pollution and human activity have something to do with it?
A Welcome Guest?
El Niño generally peaks in December. Long ago, Peruvian fishermen gave the Christmastime guest a name that in Spanish means "the child," referring to baby Jesus. But El Niño is felt long before and after December all over the world.
What's in store for the U.S.? Californians who have been enjoying El Niño's early signs are bracing for a stormy winter. On the other hand, El Niño could bring an early spring to the Northeast and fewer tornadoes to the Midwest. Says scientist James O'Brien: Most Americans can think of El Niño as a "good dude."
But El Niño has a nasty side. It has already churned out hurricanes off Mexico, sent rain to South America and caused dry spells in Australia and Indonesia. Such weather harms farming and other industries.
The worst may be ahead, say forecasters. They compare the size of this El Niño with one in 1982-83 that caused many deaths and billions of dollars in damage. "That was the biggest El Niño we know of," says climate researcher Stephen Zebiak. "Until maybe now."