What to know about the world's great climate collapse

The climate agenda's fall from grace over the past year has been stunning — in speed, scale and scope.Why it matters: Whether this collapse in climate-change ambition proves permanent or temporary will shape the planet — which is still warming in unprecedented ways — and trillions of dollars in global energy investment.Driving the news: President Trump last week announced that he's withdrawing from the world's flagship climate treaty that's been in place for more than 30 years, making the U.S. the only country not to be part of it."There's no hand-waving about how 'We want to cooperate on climate,'" oil historian and S&P Global vice chairman Dan Yergin said in an interview. "It's, 'We're slamming the door on that issue.'""We've gone from over-indexing it to zero-indexing it."The big picture: The last 30 years of global history "was an exceptionally unusual period," said Nat Keohane, president of the nonprofit Center for Climate and Energy Solutions.After the Cold War, countries — led by the U.S. — bonded together and created global institutions. "Climate policy was facilitated by multilateralism, globalization and the sense nations had a common agenda far more than the world we live in right now," Yergin said.Catch up fast: The last year has seen an epic reversal that spread quickly from governments to boardrooms to pop culture. Trump has aggressively and comprehensively dismissed climate change as a problem.Canada's Prime Minister Mark Carney, once one of the world's most vocal climate advocates, is now repealing his country's climate policies.Bill Gates circulated a memo criticizing the climate movement while shifting much of his money and focus back to public health — just four years after publishing "How to Avoid a Climate Disaster."Ford pulled back sharply from its EV ambitions, becoming a case study in the risks of betting on whipsawing government policies.Outside of North America, former U.K. Prime Minister Tony Blair also issued a memo questioning the political and economic wisdom of pursuing "net zero" policies as designed.Europe scaled back its gasoline car ban and softened climate disclosure rules, a retreat the New York Times captured with a telling headline: "Europe Begins to Tiptoe Away From Key Climate Policies."The International Energy Agency quietly restored a more conservative base-case energy scenario that it had dropped in 2020.Even Hollywood is moving on — swapping climate angst as shown in 2021's "Don't Look Up and 2023's "Extrapolations" miniseries for oil swagger, as seen in the current hit TV show "Landman."Yes, but: Climate ambition isn't collapsing everywhere — or all at once.The Times used "tiptoe" for a reason: Europe is still largely sticking to its long-term goals.Some European investment funds are still ditching American firms over sustainability concerns.China is filling much of the U.S. industrial policy vacuum — plowing ahead on cleantech funding from batteries to fusion.Trump's muscular support for nuclear fission and fusion could have the unintended consequences of helping address climate.The intrigue: These reversals represent a retreat from the goal of "net zero" emissions by 2050 — but not a wholesale retreat from climate action itself.Instead of banning gasoline cars by 2035, the European Union now requires a 90% reduction in tailpipe emissions by then. Translation: It's a pullback from a maximalist goal — but still an aggressive one.Though it deleted many Inflation Reduction Act climate provisions, Trump's One Big, Beautiful Bill Act preserved support for geothermal, energy storage and other technologies and would still rank among the biggest cleantech laws ever passed.By the numbers: Global venture capital investments in climate and clean tech deals have dropped nearly 50% since their high of 2021, according to PitchBook data compiled for Axios, but even this fall is far higher than earlier periods.The roughly $40 billion in investments last year still represents a roughly 450% increase since 2015, when the Paris Agreement was signed.Data: PitchBook; Chart: Jacque Schrag/AxiosWhat we're watching: The rush for power to fuel AI is boosting parts of climate tech — especially nuclear power — but it's far from clear whether it will be a net positive for climate efforts overall.What's next: Climate is among the official themes at the annual World Economic Forum, which meets next week in Davos, Switzerland."How can we build prosperity within planetary boundaries?" the forum asks in one theme. But the main one underscores a more fundamental challenge: "How can we cooperate in a more contested world?"The bottom line: "We're going to have to figure out how to move forward on climate in a world that's more multi-polar than it has been in a long time," Keohane said.