In 2019, the AI researcher Rich Sutton published a short essay called “The Bitter Lesson.” Seventy years of AI research, he argued, kept demonstrating the same thing: The most effective ways to train AI rely on raw, brute-force computing power — simply scaling up — rather than clever approaches built on human insight. It didn’t matter how elegant the researchers’ work was. More compute would win every time. It’s a bitter lesson because, well, no one wants to accept that even the best efforts can go unrewarded.

This summer, climate change has been teaching its own kind of bitter lesson. Last week smoke from out-of-control Canadian wildfires reached more than 120 million Americans, sending out air quality alerts across 18-plus states from Minnesota to Virginia. Those wildfires, which were made more likely by the effects of climate change, followed record-breaking heat waves in Europe that contributed to the deaths of thousands of people.

Disasters like these inevitably renew calls for climate action, but no current US emissions policy, no amount of carbon cutting now, could clear the air, just as nothing Europe has done on climate — and it has done more than any other region, at no small cost — could protect it from those killer temperatures. Not this summer, not this decade, not the one after. The steps countries take now to reduce carbon emissions, to mitigate climate change, will not protect them from the present-day effects of climate change.

That’s the bitter lesson of climate change, and 2026 is the summer it has become unignorable. The dangerous effects we’ve been warned about are here, locked in on every timescale that matters to the people living through them. We can’t prevent the worst from happening right now, so we need to figure out how we’re going to adapt to it. 

The smoke we can’t stop

Canadian wildfire smoke is as close to an unstoppable disaster as exists today. The fires are Canada’s, the ignition is mostly lightning, the fuel is a subcontinent of boreal forest no fire agency can manage, and the whole system sits outside US jurisdiction. While strategies like prescribed burning and forest thinning can help reduce the wildfires that crop up in the western US, the sheer scale of Canadian forests makes such management far more difficult, maybe impossible. There is no timescale on which American mitigation clears American air of Canadian wildfire smoke. 

What this means is that for this wildfire smoke, at this moment, adaptation may be all there is.

American law has already conceded the point. Under the Clean Air Act’s Exceptional Events Rule, a state can petition the Environmental Protection Agency to strike wildfire-smoke days from the record used to judge whether its air is legally clean. In other words, the official response to one of the country’s fastest-growing air-quality threats is to delete it from the ledger. 

It’s true that climate attribution science ties heat waves to warming with the highest confidence of any extreme, while wildfire is messier — a compound event filtered through ignition, fuel, and fire weather. But fire seasons are lengthening, fuels are drying, and the most extreme wildfire events on Earth more than doubled between 2003 and 2023. The pattern is intensifying fire in particular regions — the boreal north among them — and the smoke goes where the wind says.

And that smoke is worse than it looks. Wildfire PM2.5 — the microscopic particles that are particularly dangerous —  is roughly three to four times more toxic to the lungs, per unit of mass, than ordinary urban particulate matter. During major smoke events, pediatric asthma visits can spike by more than 30 percent, and Harvard researchers have found the cardiorespiratory damage persists for months after the sky turns blue again. That’s especially dangerous for vulnerable populations like babies and pregnant women.

We can’t affect the winds, we struggle to stop the fires, and any current attempt to reduce warming enough to make those infernos less likely won’t be felt for years. But that doesn’t mean we’re helpless to protect ourselves from wildfire smoke, any more than we are from extreme heat.

We can purify indoor air, and it costs less than you probably think. Strap four furnace filters to a box fan — creating a Corsi-Rosenthal box — and indoor PM2.5 drops by roughly half; in testing during actual wildfire smoke, a DIY unit cut fine particles by about 56 percent in a large room and close to 99 percent in a small sealed one.

For heat, the toolkit is even better known — and one of the best proofs it works is in, of all places, France. The historic 2003 heat wave killed some 15,000 people there, most of them elderly and alone. The national heat plan built in its aftermath — tiered alerts, registries of vulnerable residents, check-in calls, cool rooms — cut the death toll of comparable heat waves by roughly 90 percent: When France hit its all-time record of 114.8°F in 2019, fewer than 1,500 died, per the Christian Science Monitor. A recent European analysis estimates a rerun of 2003 would now kill 77 percent fewer people in France than in a world that never adapted.

So technologies exist to protect ourselves. What’s too often missing are the standards, money, and the drive to deploy protection before the disaster arrives instead of after.

Catching up to today

When it comes to wildfire smoke, some governments are ahead of the game — and some aren’t. Washington state, Oregon, and California now regulate outdoor workers’ smoke exposure by air-quality index, under rules like Cal/OSHA’s wildfire-smoke standard; California funds “clean air centers” with upgraded filtration where people can shelter on bad-air days; Colorado’s Clean Air for Schools program ships free HEPA units to K-12 classrooms. A purifier humming in a classroom is essentially doing for smoke what a cooling center does for heat.

When it comes to heat, some parts of Europe are catching up. Barcelona now runs a network of nearly 400 “climate shelters” — libraries, museums, retrofitted schoolyards — with the goal of putting one within a 10-minute walk of every resident. For the first time, the city is keeping libraries open through August to do it, which, as anyone who has visited Europe in the late summer knows, is no small thing.

So adaptation exists, and it is saving lives. But this summer has also shown what happens when cities, states, and countries aren’t ready. 

In the US, the Midwestern and Northeastern states that spent last week under smoke alerts have almost none of the protections against wildfire smoke that have become more common in Western states, and no one is required to build them, because the country has no enforceable national indoor air-quality standard at all. In Europe, national heat plans are still reluctant to reach for the most powerful tool on the shelf. About one European household in five has air conditioning, compared to nearly nine in ten in the US, in large part because much of the continent still treats the machine as a moral defect. 

In both cases, rich regions that have largely taken climate mitigation more seriously than some of their neighbors aren’t pursuing adaptations they need. Which really means not taking climate change as seriously as they should. 

Accepting the bitter lesson

For a generation, adaptation was the word climate advocates were often reluctant to say out loud. In his 1992 book Earth in the Balance, Al Gore called adaptation “a kind of laziness, an arrogant faith in our ability to react in time to save our skins.” (He later changed his mind.) And in fairness, “we’ll just adapt” has often been a delaying tactic, an easy out for polluters. 

But the ground has shifted under that caution, because the projections did exactly what projections are supposed to do: they came true. 

Longer fire seasons, deadlier heat waves, smoke reaching places that never used to see it — this summer is the confirmation. And that changes what seriousness requires. If you’ve spent decades warning people that the effects of climate change are coming, you can’t treat readying for those effects as a distraction from the real work. None of this argues for easing up on emissions — each ton that isn’t emitted is adaptation nobody has to build. But preparing for what you predicted is what believing your own prediction looks like.

For AI researchers, Rich Sutton’s lesson was bitter for a specific reason. Those who resisted its conclusion weren’t foolish; they resisted it because it seemed to undercut all their hard work. They resisted it because it didn’t seem fair, just as it’s not fair that countries and states that have in many ways done much to mitigate climate change find themselves just as vulnerable, if not more so, than peers that have done comparatively little. 

But here’s the other half of Sutton’s lesson: The researchers who accepted it won. They stopped defending their cleverness and built what worked. That option is open to climate politics too. The atmosphere isn’t fair, but it is consistent, and it will deliver next summer’s version of this one on schedule. We can be ready. The bitter lesson is only bitter until you have the will to act on it. 

A version of this story originally appeared in the Future Perfect newsletter. Sign up here!

The greatest threat to animals in the US and globally is the destruction of their habitat — replacing grasslands with farms, cutting forests for timber, building suburbs atop wetlands. It’s the main reason why hundreds of species have been listed under the Endangered Species Act, which gives federal protection to species that are currently at risk of extinction or are about to be. 

That’s what makes a recent move by the Trump administration both confusing and — according to many environmental advocates — incredibly alarming. 

In a rule published earlier this month, the administration determined that, in many cases, destroying the habitat of federally threatened and endangered species is no longer explicitly illegal, even if doing so could ultimately drive them extinct. The rule upends half a century of regulatory precedent that survived many Republican administrations. Environmental advocates also say it runs counter to the very intent of the Endangered Species Act, which Congress passed in 1973 with near-unanimous bipartisan support (and which Richard Nixon signed into law).

While the Trump administration has made several recent decisions that weaken protections for endangered species — amid what many scientists call an extinction crisis — this one may have the most far-ranging consequences. Here’s why. 

A rule that could blow up the ESA

The Endangered Species Act is a complicated law, but on a simple level it makes it illegal for anyone to “take” endangered species without authorization from the government. “Take” is defined in the law by 10 different terms: harass, harm, pursue, hunt, shoot, wound, kill, trap, capture, or collect.

It’s the meaning of one of those words — harm — that matters most here. Up until the recent rule, the government’s definition for harm included destroying an animal’s habitat if it impairs essential behaviors, such as breeding. That might include, say, building a hotel on top of a beach that endangered sea turtles use for nesting. Such a definition was important because destroying the habitat of an already imperiled species could push it over the edge, wildlife advocates say. What’s more is that, according to the language of the law itself, the purpose of the ESA includes conserving “ecosystems upon which endangered species and threatened species depend.”

The Trump administration, however, just threw out that definition of harm and the unambiguous protection it has long afforded habitat. And while it didn’t offer a new definition, the administration said that it agrees with a much narrower interpretation of the term — articulated three decades ago in a dissent by the late conservative Justice Antonin Scalia — that only includes actions that directly and intentionally harm individual animals, such as capturing a sea turtle to eat or keep as a pet.

“For years, federal agencies abused the ESA to obstruct lawful land use and burden American families and businesses,” Doug Burgum, Secretary of the Interior Department, which oversees endangered species protections, said in a statement. “That approach turned routine activity into a regulatory trap, drove up costs that impacted people’s lives, and expanded federal authority beyond what Congress intended. This action restores common sense, respects private property, provides much-needed certainty for landowners and follows the statute Congress actually passed.” (The Interior Department declined to provide a comment on our reporting, pointing us instead to its press release and the notice in the Federal Register.) 

Under the new rule, set to take effect in September, “harm” no longer explicitly includes actions that may accidentally or indirectly doom a wildlife population to extinction. A company building luxury villas on a private beach that endangered sea turtles need for survival would not unambiguously be considered take — and thus be illegal — unless the company knew it’d crush turtle eggs or the turtles themselves in the process. Neither would logging old-growth forests that endangered birds inhabit, building wind turbines that are known to kill endangered bats, or constructing a road that would likely get endangered snakes run over. 

The administration’s interpretation of take “really completely blows up the Endangered Species Act,” said J.B. Ruhl, a lawyer at Vanderbilt University and a leading expert on the ESA.

To be clear, these sorts of actions were never forbidden outright — and this is key. An important feature of the ESA is that, with some exceptions, it allows companies, counties and states, and federal agencies to kill or harm endangered species, as long as they take steps to limit their impact. Indeed, nonfederal organizations of all kinds have, for decades, received federal permits that allow them to “take” endangered species, in exchange for coming up with a plan to minimize the harm they may cause. In Hawaii, for example, an electric utility that operates power lines that can injure endangered birds takes steps to prevent collisions and funds an avian rehab facility that helps offset some of its impacts. 

The problem now is that these conservation plans — which wildlife advocates say are critical for species recovery — are rooted in the defunct definition of harm, according to Daniel Rohlf, a law professor at Lewis & Clark Law School. 

The whole purpose of these so-called Habitat Conservation Plans is to lessen the incidental, or accidental, impacts on endangered species, while at the same time allowing companies to still build and operate legally. But in rescinding the former definition of harm, the Trump administration has essentially just said that all that incidental killing is no longer illegal anyway. That may undermine future Habitat Conservation Plans and those that have yet to be finalized. This “pulls the rug out from under literally decades of work,” Rohlf said of the recent rule. 

Next up: The Supreme Court?

Even under the new rule, the ESA still has some important protections for habitat. When the government lists a species as threatened or endangered, for example, it usually designates what’s called “critical habitat” — areas that it deems essential to the survival of the species. Under the ESA, all federal agencies have to ensure that their actions, such as permitting new mines or wind farms, do not destroy critical habitat or jeopardize the existence of a species. Those responsibilities are still intact. 

It’s also not certain that the new rule will stick. Several environmental groups have already sued the administration to try to reinstate the former definition, alleging, among other claims, that rescinding the definition of harm violates the language and the intent of the ESA. This challenge is likely to reach the Supreme Court, Ruhl says. 

To understand what could happen next requires some important context.

Until two years ago, courts typically deferred to federal agencies to determine how to interpret ambiguous language in laws like the ESA. This legal principle was known as the Chevron doctrine. It was the Fish and Wildlife Service, for example, that published a rule decades ago clarifying that the ambiguous word harm includes destroying an endangered animal’s habitat. That interpretation survived a famous 1995 Supreme Court case, Babbitt v. Sweet Home Chapter of Communities for a Great Oregon, in which Oregon landowners and the timber industry argued that the government defined “harm” too broadly. The court decided that an “ordinary understanding” of that term “naturally encompasses habitat modification” that injures or kills endangered species.

In the summer of 2024, however, the Chevron doctrine was overturned. That means the power to interpret unclear language in laws now rests with the courts. 

The Trump administration has seized on this fact, Rohlf said. Instead of redefining what harm means, the administration simply axed the existing definition that included impacts to habitat that injure wildlife. It will now be up to the courts to decide what is considered harm in future cases brought under the ESA — such as if, say, an environmental group sues a developer, claiming that it destroyed essential habitat for an endangered species in violation of the Act. The administration did not stop short of making clear what it thinks: In the preamble to the rule, it said harm should only include actions made directly and intentionally against endangered organisms.

Wildlife advocates point out that the Supreme Court already determined that a definition of harm including habitat destruction is reasonable. That’s what Babbitt v. Sweet Home was about. But because that case rested, in part, on the now-overturned Chevron doctrine, the courts — and perhaps eventually the Supreme Court — may relitigate the meaning of harm. (The Supreme Court did make it clear that it won’t call into question decisions that relied on the Chevron doctrine before it was overturned.) 

Ultimately, it’s hard to argue that harming an endangered species, in a plain reading of the word, does not include destroying vital habitat that it needs to survive or other actions that kill or injure them indirectly, legal scholars told me. It’s also clear that Congress saw it this way when it wrote the law. There’s a whole section of the ESA about granting permits for “incidental take,” which could include damaging an animal’s habitat, according to Holly Doremus, a law professor at the University of California, Berkeley. That section only makes sense, she says, if you’re interpreting harm to include actions that accidentally and indirectly kill or injure species — which is far broader than the definition that the Trump administration would like to use.   

For the Trump administration to really get what it wants, Doremus said, it would need to remove the word “harm” from the ESA altogether. Short of that, she said, Trump officials “want to make ‘harm’ as ineffective a statutory term as possible.”

Should the administration succeed — should the courts determine that “harm” does not apply to destroying the habitat of endangered species — environmental advocates warn that the ESA will lose much of its extinction-preventing power.

“If this decision is allowed to stand, it eviscerates the statute on which imperiled species conservation has rested in this country since 1973,” said Jane Davenport, a senior attorney at Defenders of Wildlife, an advocacy group. “This is truly a stake through the heart of the ESA.”