The last time there was a major slowdown in the mighty network of ocean currents that shapes the climate around the North Atlantic, it seems to have plunged Europe into a deep cold for over a millennium.

That was roughly 12,800 years ago, when not many people were around to experience it. But in recent decades, human-driven warming could be causing the currents to slow once more, and scientists have been working to determine whether and when they might undergo another great weakening, which would have ripple effects for weather patterns across a swath of the globe.

A pair of researchers in Denmark this week put forth a bold answer: A sharp weakening of the currents, or even a shutdown, could be upon us by century’s end.

It was a surprise even to the researchers that their analysis showed a potential collapse coming so soon, one of them, Susanne Ditlevsen, a professor of statistics at the University of Copenhagen, said in an interview. Climate scientists generally agree that the Atlantic circulation will decline this century, but there’s no consensus on whether it will stall out before 2100.

Which is why it was also a surprise, Dr. Ditlevsen said, that she and her co-author were able to pin down the timing of a collapse at all. Scientists are bound to continue studying and debating the issue, but Dr. Ditlevsen said the new findings were reason enough not to regard a shutdown as an abstract, far-off concern. “It’s now,” she said.

The new research, published on Tuesday in the journal Nature Communications, adds to a growing body of scientific work that describes how humankind’s continued emissions of heat-trapping gases could set off climate “tipping points,” or rapid and hard-to-reverse changes in the environment.

Abrupt thawing of the Arctic permafrost. Loss of the Amazon rain forest. Collapse of the Greenland and West Antarctic ice sheets. Once the world warms past a certain point, these and other events could be set into swift motion, scientists warn, though the exact thresholds at which this would occur are still highly uncertain.

In the Atlantic, researchers have been searching for harbingers of tipping-point-like change in a tangle of ocean currents that goes by an unlovely name: the Atlantic Meridional Overturning Circulation, or AMOC (pronounced “AY-mock”).

These currents carry warm waters from the tropics through the Gulf Stream, past the southeastern United States, before bending toward northern Europe. When this water releases its heat into the air farther north, it becomes colder and denser, causing it to sink to the deep ocean and move back toward the Equator. This sinking effect, or “overturning,” allows the currents to transfer enormous amounts of heat around the planet, making them hugely influential for the climate around the Atlantic and beyond.

As humans warm the atmosphere, however, the melting of the Greenland ice sheet is adding large amounts of fresh water to the North Atlantic, which could be disrupting the balance of heat and salinity that keeps the overturning moving. A patch of the Atlantic south of Greenland has cooled conspicuously in recent years, creating a “cold blob” that some scientists see as a sign that the system is slowing.

Were the circulation to tip into a much weaker state, the effects on the climate would be far-reaching, though scientists are still examining their potential magnitude. Much of the Northern Hemisphere could cool. The coastlines of North America and Europe could see faster sea-level rise. Northern Europe could experience stormier winters, while the Sahel in Africa and the monsoon regions of Asia would most likely get less rain.

Evidence from ice and sediment cores indicates that the Atlantic circulation underwent abrupt stops and starts in the deep past. But scientists’ most advanced computer models of the global climate have produced a wide range of predictions for how the currents might behave in the coming decades, in part because the mix of factors that shape them is so complex.

Dr. Ditlevsen’s new analysis focused on a simple metric, based on sea-surface temperatures, that is similar to ones other scientists have used as proxies for the strength of the Atlantic circulation. She conducted the analysis with Peter Ditlevsen, her brother, who is a climate scientist at the University of Copenhagen’s Niels Bohr Institute. They used data on their proxy measure from 1870 to 2020 to calculate statistical indicators that presage changes in the overturning.

“Not only do we see an increase in these indicators,” Peter Ditlevsen said, “but we see an increase which is consistent with this approaching a tipping point.”

They then used the mathematical properties of a tipping-point-like system to extrapolate from these trends. That led them to predict that the Atlantic circulation could collapse around midcentury, though it could potentially occur as soon as 2025 and as late as 2095.

Their analysis included no specific assumptions about how much greenhouse-gas emissions will rise in this century. It assumed only that the forces bringing about an AMOC collapse would continue at an unchanging pace — essentially, that atmospheric carbon dioxide concentrations would keep rising as they have since the Industrial Revolution.

In interviews, several researchers who study the overturning applauded the new analysis for using a novel approach to predict when we might cross a tipping point, particularly given how hard it has been to do so using computer models of the global climate. But they voiced reservations about some of its methods, and said more work was still needed to nail down the timing with greater certainty.

Susan Lozier, a physical oceanographer at Georgia Tech, said sea-surface temperatures in the North Atlantic near Greenland weren’t necessarily influenced by changes in the overturning alone, making them a questionable proxy for inferring those changes. She pointed to a study published last year showing that much of the cold blob’s development could be explained by shifts in wind and atmospheric patterns.

Scientists are now using sensors slung across the Atlantic to directly measure the overturning. Dr. Lozier is involved in one of these measurement efforts. The aim is to better understand what’s driving the changes beneath the waves, and to improve projections of future changes.

But the projects began collecting data in 2004 at the earliest, which isn’t enough time to draw firm long-term conclusions. “It is extremely difficult to look at a short record for the ocean overturning and say what it is going to do over 30, 40 or 50 years,” Dr. Lozier said.

Levke Caesar, a postdoctoral researcher studying the overturning at the University of Bremen in Germany, expressed concerns about the older temperature records that Dr. Ditlevsen and Dr. Ditlevsen used to compute their proxy. These records, from the late 19th and early 20th centuries, might not be reliable enough to be used for fine-toothed statistical analysis without careful adjustments, she said.

Still, the new study sent an urgent message about the need to keep collecting data on the changing ocean currents, Dr. Caesar said. “There is something happening, and it’s likely out of the ordinary,” she said. “Something that wouldn’t have happened if it weren’t for us humans.”

Scientists’ uncertainty about the timing of an AMOC collapse shouldn’t be taken as an excuse for not reducing greenhouse-gas emissions to try to avoid it, said Hali Kilbourne, an associate research professor at the University of Maryland Center for Environmental Science.

“It is very plausible that we’ve fallen off a cliff already and don’t know it,” Dr. Kilbourne said. “I fear, honestly, that by the time any of this is settled science, it’s way too late to act.”

Last week, Representative Matt Gaetz and his wife, Ginger, arrived at a Washington reception for “Barbie” in matching pink, grinning in photos along the “pink carpet,” mingling among guests sipping pink cocktails, admiring a life-size pink toy box.

They left with political ammunition.

“The Barbie I grew up with was a representation of limitless possibilities, embracing diverse careers and feminine empowerment,” Mrs. Gaetz wrote on Twitter. “The 2023 Barbie movie, unfortunately, neglects to address any notion of faith or family, and tries to normalize the idea that men and women can’t collaborate positively (yuck).”

When another account scolded Mr. Gaetz, the hard-right and perpetually stunt-seeking Florida congressman, for attending the event at all — citing the casting of a trans actor as a doctor Barbie — Mr. Gaetz replied with a culture-warring double feature.

“If you let the trans stop you from seeing Margo Robbie,” he said, leaving the “T” off the first name of the film’s star, “the terrorists win.”

The non-terroristic winners were many after the film’s estimated $155 million debut: Ms. Robbie and Greta Gerwig, the film’s director, finding an eager audience for their pink-hued feminist opus; the Warner Bros. marketing team, whose ubiquitous campaigns plainly paid off; the film industry itself, riding “Barbie” and “Oppenheimer” to its most culturally dominant weekend in years.

But few outcomes were as nominally inexplicable (and probably inevitable) as the film’s instant utility to political actors and opportunists of all kinds. For a modern take on what was long a politically fraught emblem of toxic body image and reductive social norms, no choice was too small, no turn too ideology-affirming or apparently nefarious, for a bipartisan coalition of commentators and elected officials to see value in its dissection.

“I have, like, pages and pages of notes,” Ben Shapiro, the popular conservative commentator, said in a lengthy video review, which began with him setting a doll aflame and did not grow more charitable. (He said his producers “dragged” him to the theater.)

“I took a tequila shot every time Barbie said patriarchy … only just woke up,” wrote Elon Musk. (Mr. Shapiro, diligently but less colorfully, said he had counted the word “more than 10 times.”)

“Here are 4 ways Barbie embraces California values,” the office of Gavin Newsom, the state’s Democratic governor, wrote in a thread hailing Barbie as a champion of climate activism, “hitting the roads in her electric vehicle,” and of destigmatizing mental health care.

If there was a time in the culture when a giant summer film event was something of an American unifier — a moment to share over-buttered popcorn through big-budget shoot-’em-ups and sagas of insatiable sharks — that time is not 2023.

And, as ever, the political class’s performative investment in “Barbie” — the outrage and the embrace — can seem mostly like a winking bit.

What to make of Gov. Gretchen Whitmer, Democrat of Michigan, posting a Barbie meant to resemble herself beside the Instagram caption, “Come on Barbie, let’s go govern”?

What does it mean, exactly, when Senator Raphael Warnock, Democrat of Georgia, says of himself, “This Ken is pushing to end maternal mortality”?

Certainly, Senator Ted Cruz, Republican of Texas, has summoned practiced gravity in accusing “Barbie” of working to appease the Chinese. (Some Republicans have fixated on a scene that features a crudely drawn map that supposedly depicts the so-called nine-dash line, which indicates Chinese ownership of oceanic territory that is disputed under international law. Vietnam has banned showings of the movie in the country over that image.)

“Obviously, the little girls that are going to see Barbie, none of them are going to have any idea what those dashes mean,” Mr. Cruz told Fox News. “This is really designed for the eyes of the Chinese censors, and they’re trying to kiss up to the Chinese Communist Party because they want to make money selling the movie.”

The response on the right is not a one-off. For a generation of conservative personalities, weaned on Andrew Breitbart’s much-cited observation that “politics is downstream of culture,” Hollywood and other ostensibly liberal bastions are to be confronted head-on, lest their leanings ensnare young voters without a fight.

Recent years have provided ample evidence, some on the right say, for a “go woke, go broke” view that progressivism is bad business. Last year’s apolitically patriotic “Top Gun: Maverick” was a smashing success, as was this year’s kid-friendly “The Super Mario Bros. Movie.” By contrast, critics on the right contended that Disney’s remake of “The Little Mermaid,” with its title character portrayed by the Black actress Halle Bailey, failed to match its producers’ hopes. (Of course, there is no way to trace exactly what determines any movie’s success or failure, and many observers adhere to the screenwriter William Goldman’s axiom: “Nobody knows anything.”)

“Barbie” cannot be said to have gone broke. But its purported politics, conservatives have argued, did damage it by making it less entertaining — “a lecture,” in the words of The Federalist’s Rich Cromwell, “that self-identifies as a movie.”

Kyle Smith, a reviewer at The Wall Street Journal, complained that the film “contains more swipes at ‘the patriarchy’ than a year’s worth of Ms. magazine.”

The film seems at times (gentle spoiler alert) to be engaging with “the patriarchy” ironically, infusing it with knowing Southern California vapidity, décor that seems inspired by hair metal and a heavy emphasis on weight lifting and “brewskis.”

When it comes time (less gentle spoiler alert) to reclaim Barbie Land, the Barbies distract the Kens by indulging their tendency for exaggerated gestures of malehood like playing acoustic guitar and insisting on showing a date “The Godfather” while talking over it.

Mr. Shapiro has sounded unconvinced that the movie is broadly in on its own jokes.

“The actual argument the movie is making is that if women enjoy men, it’s because they have been brainwashed by the patriarchy,” he said in his review.

He called the film, with a straight face, two hours he will rue wasting as he sits on his deathbed.

“The things I do,” he said, “for my audience.”

Anjali Huynh contributed reporting.