Thank El Niño.
Matt Simon, Senior Staff Writer
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You are about to time travel. Off the Pacific coast of South America, the band of warm water known as El Niño is mutating into a freak of nature. At more than 3 degrees Celsius above normal, it’s the warmest El Niño recorded since satellites started measuring sea surface temperatures half a century ago, and it won’t peak for several more months, potentially hitting somewhere around 4 degrees by November or December.
“This event is already in record territory,” said Zeke Hausfather, a climate scientist at the research group Berkeley Earth. “And every model expects it to keep growing.”
At the same time, this year’s Atlantic hurricane season, which began in June, is shattering records in the opposite direction. On average, by this time of year we should have seen four hurricanes, two of them major. But so far, the Atlantic hasn’t produced even one. The previous record for the latest first hurricane in a season was September 11.
The two events on opposite sides of the Americas are individually extreme and bizarre. But while they’re both record-breaking, they’re not unexplained. In fact, they’re intertwined in a fascinating way.
To understand the link, we need to talk about the ingredients of a hurricane, which you can think of as an engine. The fuel is warm ocean water, which sends energy skyward. This is why hurricanes have grown so much more powerful and destructive in recent years: The more the planet warms, the more high-octane fuel that can go into cyclones. Additionally, hurricanes like high humidity, as masses of dry air tend to break them up. Lastly, they prefer that the wind move in a consistent direction.
The Atlantic is full of warm water right now, so the hurricanes should have fuel. But it’s the wind that’s getting in the way: El Niño increases wind shear over the Atlantic, meaning air moving in different directions and different speeds at different altitudes.