Washington, D.C. is enduring its second major snowstorm in less than a week and the third this winter season. Experts say the oceanic disturbance known as El Niño is to blame for severe weather here and around the world in recent months.
Every three to seven years or so, heat buildup in the tropical Pacific Ocean reaches a critical point, says Kevin Trenberth at the U.S. National Center for Atmospheric Research.
"In some sense," Trenberth says, "the ocean says, 'I can't stand it anymore. I'm going to have an El Niño.'"
And when it does, look out.
The warmer Pacific Ocean pours heat and moisture into the atmosphere, disturbing the usual airflow patterns and messing up weather around the world. Although the 1997-98 El Niño event was stronger, Trenberth says this current one is the strongest in a decade.
"It's still probably not in the 'major' category," he says, "but it's having some substantial influences around the world."
Storms, droughts linked
Southeast Asia felt El Niño's influence during last year's typhoon season. A series of devastating storms hit the region, killing thousands and causing massive flooding and landslides. On the other hand, dry conditions are predicted for Indonesia, raising the risk of forest fires. And farther west, late monsoon rains caused crop failures in parts of India. That has helped drive up food prices.
Although it's harder to say to what degree El Niño is to blame for India's late monsoon, Trenberth says, "It certainly doesn't help. Let me put it that way."
Some good news
But El Niño isn't all bad news. Drought-stricken California is getting some much-needed rain. And parts of Africa could benefit as well.
"The drought that's currently going on in Kenya could be alleviated by the conditions that develop in the later stages," Trenberth says. El Niño conditions are expected to continue for at least the next couple months. After that, the cycle goes into transition mode. "That's where the predictability, so to speak, is actually probably less than at any other time."
As another snowstorm blankets Washington, D.C., the prospect of more unpredictable weather is hardly a comforting thought.