Earth Took 269,000 Years to Recover From This Climate Event

A new study shows Earth’s last big carbon crisis lasted longer than we thought, and what that means for us now

It started with a rock.

I remember a paleontologist colleague telling me about crouching in the badlands of the Bighorn Basin in Wyoming, fingers coated in dust, holding a chunk of ancient mudstone between their hands. They brought it to the lab. 

I was excited. These rocks aren’t just rocks; they’re time capsules. That layer in particular was part of a stretch geologists have been poking at for decades. 

It captured a moment, 56 million years ago, when the Earth suddenly got much hotter, much faster. It’s called the Paleocene-Eocene Thermal Maximum, or PETM, and it’s one of the closest natural analogs we have to the global warming we’re driving today.

Even then, we knew the PETM was a big deal. But how long it lasted—and what ended it—has always been a bit fuzzy. Now, thanks to new work by Dr. Victor Piedrahita and his team, this ancient event may have dragged on for way longer than we thought.

And that’s kind of a big deal.

In their new paper published in Geophysical Research Letters, Dr. Piedrahita and colleagues revisit a fundamental question: how long did the PETM actually last? For years, scientists pegged the event at roughly 120,000 to 230,000 years. That was already long enough to reset ecosystems, alter ocean chemistry, and kickstart evolutionary changes. But this team used a new method and came up with a revised estimate: almost 269,000 years.

“We find that the previous concept to estimate the PETM duration using carbon isotope signals is not replicable,” the authors write. So instead of relying on a single moment in time — the “G point,” when isotope values return to pre-event levels — they used a probabilistic approach that accounts for noise in the data and uncertainty in the age models.

What they found is unsettling. The recovery alone, the time it took Earth to naturally draw down all that excess carbon, may have lasted more than 145,000 years.

That has real consequences for how we think about today.

The way we measure events like the PETM is by looking at stable carbon isotopes in the sediment record. When something dumps a bunch of light carbon into the system (e.g. methane or CO₂ from volcanoes or thawing permafrost) the isotope ratios shift dramatically. That signal gets recorded in ocean muds and buried soils.

In this study, the researchers compiled six sedimentary records: one from terrestrial Wyoming (where that rock I held was from) and five from marine sites across the globe. These records were already well-dated and detailed, which allowed the team to focus on reanalyzing them with a Monte Carlo simulation (a relatively complex statistical method) that added layers of realism. They didn’t just take the average data points; they accounted for uncertainty, measurement error, and variability in how those sediments accumulated over time.

They also tested how well the carbon isotope records fit a predictable pattern of decay, like watching the signal of a cough fade in a quiet room. And here’s where it gets interesting: in most locations, the recovery followed an exponential curve. But it stretched much longer than the “snap-back” recoveries many Earth system models assume.

In short: nature cleaned up the carbon mess slowly. VERY slowly.

There’s something a little eerie about reading this paper in 2025. Since the start of the industrial era, humans have released about 2,400 petagrams of CO₂. The PETM, by comparison, unleashed somewhere between 3,000 and 20,000 petagrams — possibly from volcanoes, possibly from methane trapped under the seafloor, or a mix of both. The scale is comparable. The speed is not.

Carbon during the PETM was released over thousands of years. We’ve done it in just a couple of centuries. That difference in pace matters. Faster emissions mean the Earth system doesn’t have time to respond gradually — it buckles.

But what this new study really drives home is how long that buckle lasts.

Even if we were to stop emissions today (we won’t), the carbon already in the system could take tens of thousands of years to rebalance. “The extended recovery time during the PETM likely means that future climate change scenarios will influence the carbon cycle for longer than most carbon cycle models predict,” said Dr. Rebecca Owen.

This doesn’t mean there’s no point in acting. Quite the opposite. It means that what we do now ripples far beyond our own lifetimes.

What’s most striking isn’t just the number—269,000 years—but the process.

The recovery wasn’t quick. It involved chemical weathering of rocks, deep ocean circulation, and burial of organic matter — natural processes that grind along at a pace you can’t rush, especially in a world full of human-mediated processes. That’s the lesson. Carbon in, fast. Carbon out, slow.

It also reframes the stakes. Climate change isn’t just about the year 2100. It’s about committing the planet to a new equilibrium that may last longer than our species has existed. That long tail of recovery is a warning: once the system tips, it doesn’t spring back.

I think about the fossil leaves I’ve examined from PETM layers, their margins riddled with insect damage from a world that got warmer, wetter, and more chaotic. Forests migrated. Mammals shrank. Oceans turned acidic. It wasn’t the end of the world — but it was the end of a world.

And this time, we’re holding the match.

The PETM isn’t just a curiosity from deep time. It’s a blueprint. It shows us that releasing vast amounts of carbon into the atmosphere doesn’t just heat the planet for a few decades; it reshapes the Earth system for hundreds of thousands of years.

Dr. Piedrahita’s work helps refine the timeline, but more importantly, it helps reset our expectations. Recovery won’t be quick. It won’t be neat. And unless we change course, we’re not just writing the next chapter of the PETM; we’re accelerating it into something new.

The good news? We still have choices.

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Best,
Sílvia P-M, PhD Climate Ages