We’re likely about to live through the strongest El Niño on record. But unlike most of the weather we talk about, that record is really, really, really long. 

Think hundreds of millions of years. 

No, scientists weren’t sitting around with rocks back then writing down whether the water in the Pacific was slightly warmer than the day before. But we do still have records. 

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Let’s take a look at two different kinds of records that put our current El Niño in context:

What sea creatures tell us about the last 15,000 years

Oceans build their own El Niño record over the years with hundreds to thousands of El Niños during that time. 

Coral is one of the best records for changes in water temperatures and salinity, making it also a good El Niño recordkeeper. 

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Corals lay down yearly growth bands, much like tree rings. Locked inside each band is a chemical fingerprint of the water's temperature and saltiness, so scientists can see which years ran warm.

When an El Niño arrives, the warm and less saline water is written into the eastern Pacific coral's structure. This reverses when El Niño goes away. 

Through these changes, you can count back how often and how strong El Niños have been. These records can go back well over 100 years while the coral is alive, but should the dead coral be deposited into the seafloor permanently, those records can go back much longer.

In a study which meteorologist Jennifer Gray covered earlier this year, scientists concluded that El Niño-driven temperature swings have been 36.5% larger in the last 40 years than they were, on average, during the preindustrial period from 1000 to 1850. They used coral rings to figure that out. 

Separate research on tiny shells from the seafloor near the Galápagos extends the story much further back. These small creatures lasted only a month, then deposited their shells in a similar way to the coral. Those creatures would record salinity and temperatures. If the seafloor showed a mixture of different records, then there was more variability in the shells. 

Through that study of shells, we know that El Niño varied less some 6,000 years ago than it does now. In other words, some evidence suggests water temperatures were more consistent several thousand years ago. 

(MORE: Strengthening El Niño pushes unusual marine life toward SoCal’s coasts)

Back to the Triassic period, before the Atlantic and the dinosaurs

Let’s first talk about Earth at that time, some 252 million years ago when Earth was entering “the Great Dying.” 

Massive volcanic carbon dioxide emissions from Siberia had just caused major warming. Most species both in the water and on land had been wiped out. 

It was a time 15°C warmer than the preindustrial era when there was just one supercontinent, called Pangea, and one singular ocean, Panthalassa. Trade winds piled warm water from one side of that ocean toward the west as it does today. 

But there was still El Niño.

Instead of a shift in warm water from Indonesia toward South America, those waters shifted from the eastern side of Pangea around the globe toward the western side of Pangea. 

It is possible that these El Niños were much stronger than those of today, according to some climate model simulations of the ancient past. But they didn’t start that way. 

(WINTER OUTLOOK: How El Niño will impact the cool season)

At the end of the Permian era (the era just before the Triassic period), the east-west difference in water temperatures across that ancient ocean and the strong trade winds that made that strong gradient possible were muted dramatically, allowing El Niños to become prominent, then grow in strength in the Triassic period. As this happened, the duration of El Niños also grew.  

These mega El Niños likely helped contribute to the mass die-off of many species. 

Rising CO2 supercharged El Niño, bringing years of drought, heat and wildfires that wiped out forests, and with fewer plants to absorb carbon, the planet kept heating up in a feedback loop that eventually overwhelmed life on land and then in the oceans.

What we’ve learned about El Niños over millions of years

El Niño has likely been around since the Earth started spinning and gained an ocean and it doesn't matter how hot the Earth is, either.

While we are likely to see our strongest El Niño in our current record books, it is nearly impossible that we'll see the strongest El Niño in Earth's history.

The strength of these climate phenomenon have changed quite a bit over the millennia and they'll continue to change.

Jonathan Belles has been a digital meteorologist for weather.com for 10 years. His favorite weather is tropical weather, but also enjoys covering high-impact weather and news stories and winter storms. He's a two-time graduate of Florida State University and a proud graduate of St. Petersburg College.