Earth was due for another year of record warmth. But this warm?

Earth is finishing up its warmest year in the past 174 years, and likely the past 125,000.

This year’s global temperatures did not just beat prior records. They left them in the dust. From June through November, the mercury spent month after month soaring off the charts. December’s temperatures have largely remained above normal.

That is why scientists are sifting through evidence to see whether this year might reveal something new about the climate and what we are doing to it.

One hypothesis, perhaps the most troubling, is that the planet’s warming is accelerating, that the effects of climate change are barreling our way more quickly than before.

“What we’re looking for, really, is a bunch of corroborating evidence that all points in the same direction,” said Chris Smith, a climate scientist at the University of Leeds. “Then we’re looking for causality. And that will be really interesting.”

As extreme as this year’s temperatures were, they did not catch researchers off guard. Scientists’ computational models offer a range of projected temperatures, and 2023’s heat is still broadly within this range, albeit on the high end.

On its own, one exceptional year would not be enough to suggest something was faulty with the computer models, said Andrew Dessler, an atmospheric scientist at Texas A&M University. Global temperatures have long bobbed up and down around a steady warming trend because of cyclical factors like El Nino, possibly signaling more record heat to come in 2024.

“Your default position has to be, ‘The models are right,’ ” Dessler said. “I’m not willing to say that we’ve ‘broken the climate’ or there’s anything weird going on until more evidence comes in.”

Using Earth’s distant past to make inferences about climate in the coming years and decades can be tricky. Still, the planet’s deep history highlights how extraordinary the present era is, said Bärbel Hönisch, a scientist at Columbia University’s Lamont-Doherty Earth Observatory.

Fifty-six million years ago, for instance, geologic turmoil added carbon dioxide to the atmosphere in quantities comparable to what humans are adding today. Temperatures jumped. The oceans grew acidic. Species died en masse.

“The difference is that it took about 3,000 to 5,000 years to get there” back then, Hönisch said, compared with a few centuries today.

It then took Earth even longer to neutralize that excess carbon dioxide: about 150,000 years.

This article originally appeared in The New York Times.