Six things scientists say you need to know about El Niño
By Andrew Freedman, CNN
(CNN) — As the near-certainty of a record-breaking super El Niño has become clear, the scientists who predict and study it have been inundated by inquiries from the press and public. While there seems to be widespread recognition of what the term “El Niño” means, many people are confused about how El Niño may affect them and its ties to extreme weather events, among other things.
Here are the top 6 confusing things about El Niño, as relayed to CNN via meteorologists and climate scientists.
Every El Niño is different
Scientists talk about likely outcomes enough that it’s easy to assume all El Niño events have the same impacts — that an El Niño year will mean more rain in California, for example. But each El Niño event is actually distinct. You can see that in the way the 2015-to-2016 super El Niño failed to deliver excessive rainfall to California, despite predictions — based on previous super El Niño events — that it would.
Part of the reason for the idiosyncratic nature of El Niño events is that they don’t act alone, but instead interact with other influences on weather patterns, such as the polar vortex and different ocean and atmospheric weather and climate cycles.
According to veteran El Niño researcher Michael McPhaden, El Niño comes in all shapes and sizes, and “no two are exactly the same.”
“There’s a tremendous amount of chaos in the climate system,” he said.
El Niño can actually be good news … for some
It can be tempting to view El Niño — and the extreme weather events it contributes to — as all bad news. But some areas can benefit from this climate cycle. For example, the Atlantic hurricane season has been unusually quiet this year, with just one hurricane forming so far (though it unfortunately struck the US).
That dearth of storms is directly tied to El Niño and the way it creates strong winds in the upper atmosphere over the tropical Atlantic, which have a tendency to tear fledgling tropical storms and hurricanes apart before they can do damage. In addition, parts of the US can have warmer-than-average winters during El Niño years, lowering heating costs.
Of course, El Niño will still be bad news for other regions. At the same time as it’s prevented hurricanes from forming in the Atlantic, El Niño has led to a frenzy of hurricane activity in the eastern and central Pacific, with three storms impacting Hawaii in just one season.
You can’t surf a Kelvin wave
Kelvin waves are a key player in contributing to the formation and maintenance of an El Niño event, but their effects are largely felt under the ocean’s surface, where they transport huge amounts of ocean heat from the western Pacific to the central and eastern Pacific.
“A Kelvin wave is not a tsunami or a wall of water,” said Dillon Amaya of North Carolina State University, who has been closely following Kelvin waves’ progress into California during this El Niño.
After coming ashore in South America, such waves can then move north along the West Coast, where they can temporarily raise sea levels by 6 inches to a foot. But they do so slowly. If you were sitting on a beach looking at the water and a Kelvin wave were to lumber through, it’s unlikely that you’d even be able to see it.
“It’s an increase in the height of the nearest ~15 miles of water to the coast of 6-12 inches,” Amaya said. “Because that signal is so wide relative to the vertical change, it’s going to be hard for people to see in the same way they see a crashing wave.”
Kelvin waves are important not only for their role in heat transport, but because they make the coastline more vulnerable to flooding during astronomical high tides and winter storms.
El Niño is different from human-caused climate change
The relationship between climate change and El Niño is a subject of active scientific research, with some studies showing that human-caused climate change could exacerbate the effects of El Niño events, and others coming to different conclusions.
One recent study did show that climate change is leading to stronger El Niño episodes, but that is viewed in the scientific community as a new finding that needs to be replicated via other studies before it is widely accepted.
At the same time, this super El Niño is occurring in a world in which the oceans are already record warm, adding heat on top of heat. El Niño events release stored heat from the ocean and transfer some of it into the atmosphere, boosting global average air temperatures for one to two years on top of climate change trends.
For this reason, it is very likely that 2026 and especially 2027 will set records for the planet’s warmest years to date.
The bottom line is that El Niño is a naturally occurring phenomenon that takes place about every three to seven years, with a minority of these events becoming strong enough to earn the informal designation of a super El Niño.
El Niño doesn’t change much from day to day
The National Oceanic and Atmospheric Administration puts far more emphasis on weekly to monthly El Niño data than daily information, because there is so much variability in the day-to-day sea surface temperatures in the Pacific.
But because of the increased availability of daily ocean temperature data, many scientists are communicating on social media via vibe-coded dashboards, with daily data, leading to some confusion about whether and when El Niño has exceeded a historical benchmark.
By our count, using the weekly numbers from NOAA’s new “Relative Oceanic Niño Index,” El Niño is on track to set an all-time intensity record in November or December, and is running at or just above record levels for this time of year.
El Niño influences storms — but it’s not a storm, itself
Many people want to know how this El Niño will affect them, but we can’t tell you the time and place. El Niño is not a storm that hits at a particular location, but rather a long duration phenomenon that tilts the odds in favor of extreme weather and climate events for certain areas.
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