This story was originally published by the Guardian and is reproduced here as part of the Climate Desk collaboration.

Donald Trump’s new term as US president poses a grave threat to the planet if it blows up the international effort to curb dangerous global heating, stunned climate experts have warned in the wake of his decisive election victory.

Trump’s return to the White House is widely expected to result in the US, yet again, exiting the Paris climate agreement and may even remove American involvement in the underpinning United Nations framework to deal with the climate crisis.

While campaigning for president, Trump has called climate change “a big hoax,” scorned wind energy and electric cars, and vowed to gut environmental rules and the “green new scam” of the Inflation Reduction Act, a major bill passed by Democrats to support clean energy projects.

Trump’s agenda, analysts have found, risks adding several billion metric tons of extra heat-trapping gases to the atmosphere, further imperiling goals to stave off disastrous global heating that governments are already failing to meet. Michael Mann, a climate scientist at the University of Pennsylvania, said that the US is now a “failed democracy” and that “we now pose a major threat to the planet.”

The election result will send shockwaves through annual UN climate talks that start in Azerbaijan on Monday. “The election of a climate denier to the US presidency is extremely dangerous for the world,” said Bill Hare, a senior scientist at Climate Analytics, who warned a Trump administration would likely “damage efforts” to keep the world from heating by more than 2.5 degrees above pre-industrial levels, a Paris target that now appears even further out of reach.

While President Joe Biden’s administration will send a delegation to the COP29 summit next week, this will be overshadowed by an incoming Trump government that threatens to disengage with other major carbon emitters, such as China, to address the climate crisis. “The nation and world can expect the incoming Trump administration to take a wrecking ball to global climate diplomacy,” said Rachel Cleetus, policy director at the Union of Concerned Scientists.

Across Europe, climate activists and politicians who support stronger action to cut pollution reacted with despair to the news of Trump’s win. “This is a dark day in the US and globally,” said Thomas Waitz, an Austrian member of the European Parliament and co-chair of the European Green Party.

Luisa Neubauer, a German climate activist from the Fridays for Future movement, who went door-knocking for Kamala Harris, compared the feeling to a bad breakup. “A decision over parts of the near future has been made and most of us didn’t have a say in it,” she said. “And for a moment, it feels like the world is going to end. It’s not. But the heartbreak is real.”

“No matter what Trump may say, the shift to clean energy is unstoppable and our country is not turning back.”

But they also urged supporters of climate action to not give up.

Areeba Hamid, joint executive director of Greenpeace UK, said it was “an election won with corporate cash, big polluter backers, and disinformation,” but a global movement was already fighting to rein in the damage.

“We simply don’t have any more time to waste,” she added. “Whatever a Trump presidency chooses to do on global climate action, we know that damage can be contained if the grown-ups in the room speak up.”

When he was last president, Trump took several months to decide to remove the US from the Paris deal, raising fears the agreement would collapse. Countries did manage to avoid such a fate prior to Biden reentering the pact, and there is some optimism that the transition to cleaner energy isn’t something that Trump—despite his demands that the US “drill, baby, drill” for oil and gas—can reverse.

“The US election result is a setback for global climate action, but the Paris agreement has proven resilient and is stronger than any single country’s policies,” said Laurence Tubiana, chief executive of the European Climate Foundation and a key architect of the Paris deal.

“The context today is very different to 2016,” she said. “There is powerful economic momentum behind the global transition, which the US has led and gained from, but now risks forfeiting. The devastating toll of recent hurricanes was a grim reminder that all Americans are affected by worsening climate change.”

Much like after the previous withdrawal, cities and state within the US committed to climate action will try to fill the void of federal indifference, acting as de facto representatives at global summits and even engaging with other countries on how to cut emissions.

“No matter what Trump may say, the shift to clean energy is unstoppable and our country is not turning back,” said Gina McCarthy, former climate adviser to Biden and co-chair of the America Is All In coalition of climate-concerned states and cities.

“Our coalition is bigger, more bipartisan, better organized, and fully prepared to deliver climate solutions, boost local economies, and drive climate ambition,” she said. “We cannot and will not let Trump stand in the way of giving our kids and grandkids the freedom to grow up in safer and healthier communities.”

Domestically, environmental groups have said they will attempt to rally Democrats, as well as some Republicans, to oppose Trump’s tearing down of climate policies, which is anticipated to include major cuts to the Environmental Protection Agency and weakened pollution rules for coal plants, cars, and fossil fuel drilling. “President Trump will face a bipartisan wall of opposition if he attempts to rip away clean energy incentives now,” said Dan Lashof, director of the World Resources Institute.

However, Trump’s election victory has been a deeply sobering one for those concerned about the climate crisis. The issue was barely championed by Harris, the Democratic nominee, with polling showing that voters considered it a minor priority despite scientists’ warnings of record-breaking temperatures and two devastating, heat-fueled hurricanes that smashed into the Southeast just a few weeks before Election Day.

“This should be a wake-up call—the climate movement urgently needs more political power because the climate crisis is moving infinitely faster than our politics right now,” said Nathaniel Stinnett, founder of the Environmental Voter Project, which sought to turn out the vote among environmentalists in the US.

“We must work every day to build an unstoppable bloc of climate voters, because we’re running out of time.”