The End of Climate Science

“I am increasingly becoming irrelevant in the public conversation,” says Kate Marvel, a climate scientist who until recently worked at NASA’s Goddard Institute for Space Studies. “And I love it.”

For years, such an exalted state was denied to Marvel. Every week, it seemed, someone — a high-profile politician, maybe, or a CEO — would say something idiotic about climate science. Journalists would dutifully call her to get a rebuttal: Yes, climate change is real, she would say, yes, we’re really certain. The media would print the story. Rinse, repeat.

A few years ago, she told a panel, half as a joke, that her highest professional ambition was not fame or a Nobel Prize but total irrelevance — a moment when climate scientists would no longer have anything useful to tell the public.

That 2020 dream is now her 2023 reality. “It’s incredible,” she told me last week. “Science is no longer even a dominant part of the climate story anymore, and I think that’s great. I think that represents just shattering progress.”

We were talking about a question, a private heresy, I’ve been musing about for some time. Because it’s not just the scientists who have faded into the background — over the past few years, the role of climate science itself has shifted. Gradually, then suddenly, a field once defined by urgent questions and dire warnings has become practical and specialized. So for the past few weeks, I’ve started to ask researchers my big question: Have we reached the end of climate science?

“Science is never done,” Michael Oppenheimer, a professor of geosciences and international affairs at Princeton, told me. “There’s always things that we thought we knew that we didn’t.”

“Your title is provocative, but not without basis,” Katharine Hayhoe, a climate scientist at Texas Tech University and one of the lead authors of the National Climate Assessment, said.

Not necessarily no, then. My question, I always clarified, had a few layers.

Since it first took shape, climate science has sought to answer a handful of big questions: Why does Earth’s temperature change so much across millennia? What role do specific gases play in regulating that temperature? If we keep burning fossil fuels, how bad could it be — and how hot could it get?

The field has now answered those questions to any useful degree. But what’s more, scientists have advocated and won widespread acceptance of the idea that inevitably follows from those answers, which is that humanity must decarbonize its economy as fast as it reasonably can. Climate science, in other words, didn’t just end. It reached its end — its ultimate state, its Really Big Important Point.

In the past few years, the world has begun to accept that Really Big Important Point. Since 2020, the world’s three largest climate polluters — China, the United States, and the European Union — have adopted more aggressive climate policies. Last year, the global clean-energy market cracked $1 trillion in annual investment for the first time; one of every seven new cars sold worldwide is now an electric vehicle. In other words, serious decarbonization — the end of climate science — has begun.

At the same time, climate science has resolved some of its niggling mysteries. When I became a climate reporter in 2015, questions still lingered about just how bad climate change would be. Researchers struggled to understand how clouds or melting permafrost fed back into the climate system; in 2016, a major paper argued that some Antarctic glaciers could collapse by the end of the century, leading to hyper-accelerated sea-level rise within my lifetime.

Today, not all of those questions have been completely put aside. But scientists now have a better grasp of how clouds work, and some of the most catastrophic Antarctic scenarios have been pushed into the next century. In 2020, researchers even made progress on one of the oldest mysteries in climate science — a variable called “climate sensitivity” — for the first time in 41 years.

Does the field have any mysteries left? “I wouldn’t go quite so far as angels dancing on the head of a pin” to describe them, Hayhoe told me. “But in order to act, we already know what we need.”

“I think at the macro level, what we discover [next] is not necessarily going to change policymakers’ decisions, but you could argue that’s been true since the late 90s,” Zeke Hausfather, a climate scientist at Berkeley Earth, agreed.

“Physics didn’t end when we figured out how to do engineering, and now they are both incredibly important,” Marvel said.

Yet across the discipline, you can see research switching their focus from learning to building — from physics, as it were, to engineering. Marvel herself left NASA last year to join Project Drawdown, a nonprofit that focuses on emissions reduction. Hausfather now works at Frontier, a tech-industry consortium that studies carbon-removal technology. Even Hayhoe — who trained as a climate scientist — joined a political-science department a decade ago. “I concluded that the biggest barriers to action were not more science,” she said this week.

To fully understand whether climate science has ended, it might help to go back to the very beginning of the field.

By the late 19th century, scientists knew that Earth was incredibly ancient. They also knew that over long enough timescales, the weather in one place changed dramatically. (Even the ancient Greeks and Chinese had noticed misplaced seashores or fossilized bamboo and figured out what they meant.) But only slowly did questions from chemistry, physics, and meteorology congeal into a new field of study.

The first climate scientist, we now know, was Eunice Newton Foote, an amateur inventor and feminist. In 1856, she observed that glass jars filled with carbon dioxide or water vapor trapped more of the sun’s heat than a jar containing dry air. “An atmosphere of that gas,” she wrote of CO₂, “would give to our earth a high temperature.”

But due to her gender and nationality, her work was lost. So the field began instead with the contributions of two Europeans: John Tyndall, an Irish physicist who in 1859 first identified which gases cause the greenhouse effect; and Svante Arrhenius, a Swedish chemist who in 1896 first described Earth’s climate sensitivity, perhaps the discipline’s most important number.

Arrhenius asked: If the amount of CO₂ in the atmosphere were to double, how much would the planet warm? Somewhere from five to six degrees Celsius, he concluded. Although he knew that humanity’s coal consumption was causing carbon pollution, his calculation was a purely academic exercise: We would not double atmospheric CO₂ for another 3,000 years.

In fact, it might take only two centuries. Atmospheric carbon-dioxide levels are now 50 percent higher than they were when the Industrial Revolution began — we are halfway to doubling.

Not until after World War II did climate science become an urgent field, as nuclear war, the space race, and the birth of environmentalism forced scientists to think about the whole Earth system for the first time — and computers made such a daring thing possible. In the late 1950s and 1960s, the physicists Syukuro Manabe and Richard Wetherald produced the first computer models of the atmosphere, confirming that climate sensitivity was real. (Last year, Manabe won the Nobel Prize in Physics for that work.) Half a hemisphere away, the oceanographer Charles Keeling used data collected from Hawaii’s Mauna Loa Observatory to show that fossil-fuel use was rapidly increasing the atmosphere’s carbon concentration.

Suddenly, the greenhouse effect — and climate sensitivity — were no longer theoretical. “If the human race survives into the 21st century,” Keeling warned, “the people living then … may also face the threat of climatic change brought about by an uncontrolled increase in atmospheric CO₂ from fossil fuels.”

Faced with a near-term threat, climate science took shape. An ever-growing group of scientists sketched what human-caused climate change might mean for droughts, storms, floods, glaciers, and sea levels. Even oil companies opened climate-research divisions — although they would later hide this fact and fund efforts to discredit the science. In 1979, the MIT meteorologist Jules Charney led a national report concluding that global warming was essentially inevitable. He also estimated climate sensitivity at 1.5 to 4 degrees Celsius, a range that would stand for the next four decades.

“In one sense, we’ve already known enough for over 50 years to do what we have to do,” Hayhoe, the Texas Tech professor, told me. “Some parts of climate science have been simply crossing the T’s and dotting the I’s since then.”

Crossing the T’s and dotting the I’s—such an idea would have made sense to the historian Thomas Kuhn. In his book, The Structure of Scientific Revolutions, he argued that science doesn’t progress in a dependable and linear way, but through spasmodic “paradigm shifts,” when a new theory supplants an older one and casts everything that scientists once knew in doubt. These revolutions are followed by happy doldrums that he called “normal science,” where researchers work to fit their observations of the world into the moment’s dominant paradigm.

By 1988, climate science had advanced to the degree that James Hansen, the head of NASA’s Goddard Institute, could confidently warn the Senate that global warming had begun. A few months later, the United Nations convened the first Intergovernmental Panel on Climate Change, an expert body of scientists asked to report on current scientific consensus.

Yet core scientific questions remained. In the 1990s, the federal scientist Ben Santer and his colleagues provided the first evidence of climate change’s “fingerprint” in the atmosphere — key observations that showed the lower atmosphere was warming in such a way as to implicate carbon dioxide.

By this point, any major scientific questions about climate change were effectively resolved. Paul N. Edwards, a Stanford historian and IPCC author, remembers musing in the early 2000s about whether the IPCC’s physical-science team should pack it up: They had done the job and shown that climate change was real.

Yet climate science had not yet won politically. Santer was harassed over his research; fossil-fuel companies continued to seed lies and doubt about the science for years. Across the West, only some politicians acted as if climate change was real; even the new U.S. president, Barack Obama, could not get a climate law through a liberal Congress in 2010.

It took one final slog for climate science to win. Through the 2010s, scientists ironed out remaining questions around clouds, glaciers, and other runaway feedbacks. “It’s become harder in the last decade to make a publicly skeptical case against mainstream climate science,” Hausfather said. “Part of that is climate science advancing one funeral at a time. But it’s also become so clear and self-evident — and so much of the scientific community supports it — that it’s harder to argue against with any credibility.”

Three years ago, a team of more than two dozen researchers — including Hausfather and Marvel — finally made progress on solving climate science’s biggest outstanding mystery, cutting our uncertainty around climate sensitivity in half. Since 1979, Charney’s estimate had remained essentially unchanged; it was quoted nearly verbatim in the 2013 IPCC report. Now, scientists know that if atmospheric CO₂ were to double, Earth’s temperature would rise 2.6 to 3.9 degrees Celsius.

That’s about as much specificity as we’ll ever need, Hayhoe told me. Now, “we know that climate sensitivity is either bad, really bad, or catastrophic.”

So isn’t climate science over, then? It’s resolved the big uncertainties; it’s even cleared up climate sensitivity. Not quite, Marvel said. She and other researchers described a few areas where science is still vital.

The first — and perhaps most important — is the object that covers two-thirds of Earth’s surface area: the ocean, Edwards told me. Since the 1990s, it has absorbed more than 90% of the excess heat caused by greenhouse gases, but we still don’t understand how it formed, much less how it will change over the next century.

Researchers also know some theories need to be revisited. “Antarctica is melting way faster than in the models,” Marvel said, which could change the climate much more quickly than previously imagined. And though the runaway collapse of Antarctica now seems less likely, we could be wrong, Oppenheimer reminded me. “The money that we put into understanding Antarctica is a pittance compared to what you would need to truly understand such a big object,” he said.

And these, mind you, are the known unknowns. There’s still the chance that we discover some huge new climatic process out there — at the bottom of the Mariana Trench, perhaps, or at the base of an Antarctic glacier — that has so far eluded us.

Yet in the wildfires of the old climate science, a new field is being born. The scientists who I spoke with see three big projects.

First, in the past decade, researchers have gotten much better at attributing individual weather events to climate change. They now know that the Lower 48 states are three times more likely to see a warm February than they would without human-caused climate change, for instance, or that Oregon and Washington’s record-breaking 2021 heat wave was “virtually impossible” without warming. This work will keep improving, Marvel said, and it will help us understand where climate models fail to predict the actual experience of climate change.

Second, scientists want to make the tools of climate science more useful to people at the scales where they live, work, and play. “We just don’t yet have the ability to understand in a detailed way and at a small-enough scale” what climate impacts will look like, Oppenheimer told me. Cities should be able to predict how drought or sea-level rise will affect their bridges or infrastructure. Members of Congress should know what a once-in-a-decade heat wave will look like in their district five, 10, or 20 years hence.

“It’s not so much that we don’t need science anymore; it’s that we need science focused on the questions that are going to save lives,” Oppenheimer said. The task before climate science is to steward humanity through the “treacherous next decades where we are likely to warm through the danger zone of 1.5 degrees.”

That brings us to the third project: That climatologists must create a “smoother interface between physical science and social science,” he said. The Yale economist Richard Nordhaus recently won a Nobel Prize for linking climate science with economics, “but other aspects of the human system are still totally undone.” Edwards wanted to get beyond economics altogether: “We need an anthropology and sociology of climate adaptation,” he said. Marvel, meanwhile, wanted to zoom the lens beyond just people. “We don’t really understand ... what the hell plants do,” she told me. Plants and plankton have absorbed half of all carbon pollution, but it’s unclear if they’ll keep doing so or how all that extra carbon has changed how they might respond to warming.

Economics, sociology, botany, politics — you can begin to see a new field taking shape here, a kind of climate post-science. Rooted in climatology’s theories and ideas, it stretches to embrace the breadth of the Earth system. The climate is everything, after all, and in order to survive an era when human desire has altered the planet’s geology, this new field of study must encompass humanity itself — and all the rest of the Earthly mess.

Nearly a century ago, the philosopher Alexander Kojéve concluded it was possible for political philosophy to gain a level of absolute knowledge about the world and, second, that it had done so. In the wake of the French Revolution, some fusion of socialism or capitalism would win the day, he concluded, meaning that much of the remaining “work to do” in society lay not in large-scale philosophizing about human nature, but in essentially bureaucratic questions of economic and social governance. So he became a technocrat, and helped design the market entity that later became the European Union.

Is this climate science’s Kojéve era? It just may be — but it won’t last forever, Oppenheimer reminded me.

“Generations in the future will still be dealing with this problem,” he said. “Even if we get off fossil fuels, some future idiot genius will invent some other climate altering substance. We can never put climate aside — it’s part of the responsibility we inherited when we started being clever enough to invent problems like this in future.”