Tricky Niño

Studies say our planet’s changing climate is likely to make hurricanes more intense, trigger more outbreaks of the polar vortex, and bring more big thunderstorms and flooding rains to the American heartland. But no one is sure just what will happen to the biggest weather maker of all, El Niño. In fact, a recent study says that natural changes in El Niño make it hard to forecast how it might be altered by human-caused climate change.

El Niño is a warming of the surface waters of the Pacific Ocean, near the equator. It starts near Asia, then migrates toward South America. It can influence the weather across much of the planet. It brings floods to some regions and droughts to others. Here in the United States, it can make winters in the north much warmer than normal, while making the southwest much wetter.

It occurs every few years—usually alternating with its mirror image, La Niña. But both the timing and the intensity are hard to predict.

A team led by researchers at the University of Texas at Austin looked at changes in El Niño over the past 9,000 years. The team compared models of how the climate behaves to records of past climate preserved in ancient corals. It found that over that time, the number of strong El Niños increased. But compared to natural fluctuations in the cycle, the change is small. And there are many uncertainties in the numbers.

So it’s hard to know what our changing climate will do to big bad El Niño in the decades ahead.