La Nina and El Nino graphic

As human activities release greenhouse gases into the atmosphere, the climate warms. And when an El Niño rolls around, it acts as …

Henson: “… the icing on top of the unsavory cake.”

That’s Weather Underground meteorologist Bob Henson. He says El Niños and La Niñas are ocean and atmosphere interactions driven by water temperatures in the tropical Pacific Ocean. Warming waters fuel El Niño, and cooling drives La Niña. These events can cause extreme weather around the world. Each one generally lasts for a year or two.

Henson: “We usually won’t go more than a few years without one. And they generally kind of alternate, but you can get several in a row, too. And so there’s some regularity and some variability with both of them.”

Global temperatures tend to spike during an El Niño and come down a bit during La Niña. So these cycles can amplify the effects of climate change.

Henson: “This is what gives you the peaks and valleys on that steady climb caused by greenhouse gases.”

For example, the world experienced record-breaking heat in 2015 during the recent El Niño. Scientists say global temperatures would have broken records anyway, but the El Niño boosted them even higher.

And as the world warms, the weather during future El Niños will probably be even more extreme.

Reporting credit: ChavoBart Digital Media.

Bud Ward was editor of Yale Climate Connections from 2007-2022. He started his environmental journalism career in 1974. He later served as assistant director of the U.S. Congress's National Commission...