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Planet Earth

With a Strong El Niño Now Very Likely, What Should We Expect?

Strong El Niños tip the odds toward certain extremes in the United States and many other parts of the world, but nothing is guaranteed.

ImaGeo iconImaGeoBy Tom YulsmanSep 19, 2023 11:15 AM
El Niño Strengthens
Sea surface temperatures along the equator west of South America have been much warmer than average — a signature of El Niño. The odds are now favoring a strong El Niño episode. (Credit: earth.nullschool.net with annotations added)

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If you've been hoping for a reprieve from extreme weather, I've got disappointing news: While there are no guarantees of what it will bring, El Niño is growing and the odds that it will peak as a strong event are stronger now than scientists believed just one month ago.

According to the latest forecast, the climate phenomenon almost certainly will stick around through March of 2024. And there's now a greater than 70 percent chance that it will peak this winter as a strong episode. That's up from a two-in-three chance forecast in August.

Before we get to the specifics of how this might affect our weather, it's important to keep an important caveat in mind. As meteorologist Tom DiLiberto, writing in NOAA's ENSO Blog, puts it: "Remember . . . a strong El Niño does not necessarily mean strong El Niño impacts locally. Instead, it means a stronger chance that El Niño impacts will occur."

So read on to learn what El Niño might be brewing up for us, but also remember that this is about odds, not certainty.

El Niño's Reach

El Niño is centered in the equatorial Pacific Ocean. It is characterized by warmer-than-normal waters at the sea surface extending west from South America in a long swath along the equator. Through the oceanic heat El Niño pumps into the atmosphere, and the impact this has on how weather systems move, its reach extends far afield — and even to the planet as a whole.

El Niño's impact is now piling on to the exceedingly warm temperatures experienced by the world's oceans for months now. And this, in turn, is expected to drive Earth to a record high temperature for 2023.

Typical El Niño impacts across North America during winter. (Credit: NOAA/Climate.gov)

In the United States, the climate phenomenon exerts its strongest influence between December and February. For much of the southern portion of the country, it tilts the odds toward wetter- and cooler-than-average conditions, while the northern tier of states tends to be warmer and drier.

But check out the maps directly below depicting precipitation patterns during El Niño winters. They clearly show that no two episodes are the same. (Click here for a larger version of the graphic.) That said, the stronger the El Niño, the more consistent the impacts.

This collection of maps shows winter U.S. precipitation (December-February) compared to the 1981-2010 average during all 24 El Niño events since 1950. Years are ranked from strongest El Niño at top left to weakest at bottom right. (Credit: ENSO Blog/NOAA)

Among the most consistent impacts is a tendency toward dry conditions in the Ohio and Tennessee valleys during strong El Niños. The opposite is typically found along the U.S. Gulf Coast, where a consistent pattern of particularly wet conditions has been observed. The same goes for the Southwest and much of California. For the Golden State in particular, strong El Niño's often are synonymous with powerful storms, flooding, landslides and coastal erosion.

But again, these impacts are not ensured during every El Niño, not even the strongest ones. This point was driven home by last winter's La Niña, El Niño's opposite, which usually tilts the odds toward drier and warmer weather in much of California. Iinstead, it looked a hell of a lot like El Niño in California, which got walloped by record-breaking precipitation.

Beyond the United States

El Niño can also bring devastating deluges and desicating droughts to many other parts of the world.

For example, during the strong El Niño of 2015 and 2016, the disruption to weather patterns helped bring on what NOAA described as a "record-smashing hurricane season" in the central North Pacific. Meanwhile, the Caribbean suffered a 500-year drought, which dried up water supplies, triggering water rationing and forcing large numbers of farmers out of business.

In Indonesia, El Niño-linked drought spurred intense fires.

Heavy smoke from El Niño-linked fires blanketed Sumatra and Borneo in September and October 2015, as observed by NASA’s Terra satellite. (Credit: NASA Earth Observatory)

Drying of forests had allowed seasonal burning of nearby agricultural lands to get wildly out of control. The forest and peatland fires released enormous amounts of carbon dioxide, contributing to what at the time was the largest one-year jump in atmospheric CO2 levels ever recorded. And the smoke was estimated to have caused 100,000 premature deaths.

The strong 2015/2016 El Niño also was tied to disease outbreaks around the world, a NASA study showed. In Colorado and New Mexico, for example, increased precipitation and milder temperatures spurred growth of vegetation that provided more food for rodents that cary hantavirus, which can cause severe illness and even death. Cases of the disease increased, as did plague, spread by fleas.

With increased rainfall in parts of East Africa, sewage surged into local water sources, causing cholera cases to rise. Hotter and drier conditions in Brazil and Southeast Asia sent mosquitoes swarming into cities to find the open water sources they need to breed, causing dengue fever to proliferate.

But This Year Is Like None Other

Will this coming winter bring impacts like the ones we saw during the very strong El Niño of 2015/2016? Only time will tell, of course. But there is one factor to keep an eye on: that record-setting heat across most of the world's oceans. Previous El Niños haven't occurred concurrently with conditions looking anything like this.

The global average sea surface temperature in August 2023 set a new record high. As this map shows, some areas were particularly warm, afflicted by sizzling oceanic heat waves. Also evident is the spear of warmth along the equator characteristic of El Niño. (Credit: NOAA)

Referring to the map above of sea surface temperatures, climate scientist Jennifer Francis described the situation this way on X (the platform formerly known as Twitter):

"El Nino is getting most of the media attention, but IMO the ocean heatwaves elsewhere will also be messing with weather patterns in coming months. Note those dark red colors are 9 deg F above average, which is an absurd amount of ocean warming."

Given all of this, I think this is the best advice: buckle up!

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