The youth climate movement that formed under the first Trump presidency is gearing up for his second.

Activists in groups like the Sunrise Movement, Zero Hour and Fridays for Future have pushed for the Biden administration to step up climate action before its exit next month: They want land protected as national monuments, permits denied for liquid natural gas projects, funds allocated from the Inflation Reduction Act and the Dakota Access Pipeline shut down for good.

After the inauguration, they’ll retrench. They might ease off the mass marches and school strikes that built their platform, while refining new strategies like focusing on state politics, reducing the use of fossil fuels at a local level, and re-energizing the country to elect climate-conscious leaders.

The youth climate movement, which widely defines itself as people under 35, celebrated the 2022 passage of the Inflation Reduction Act, the biggest climate law in U.S. history. Among other things, it created a conservation-focused job corps for young people.

But the movement also ran into real-world obstacles: a pandemic, disagreements over how to address climate change, and simply the passage of time.

“What always makes this movement so difficult to maintain is that they don’t remain children,” said Viktoria Spaiser, an associate professor in sustainability research at the University of Leeds who has studied the youth climate movement. “They become adults and necessarily move on in different activities, so they can’t maintain the claim that they’re the youth” indefinitely.

The 2018 child activists who were in middle and high school are now in their 20s, moving through college and into their careers. They’re facing the conflict so many generations before them have grappled with: how to balance the scales between hope and despair.

“Covid was a really dark time and made us all slow down and face things,” said Jamie Margolin, the former executive director of Zero Hour. “I’m trying to fight my own cynicism and find a place to actually do the work because who everyone got to know, me at 17, is not the same person I am now at 22.”

Ms. Margolin was thrust into the global spotlight at 16, in the wake of a brutal fire season that spewed smog over her hometown of Seattle in 2017, around the time that Mr. Trump pulled out of the Paris climate accord and Hurricane Maria devastated Puerto Rico.

Ms. Margolin and three friends channeled their pent-up frustration over climate change into a continent-spanning youth march in 2018. Soon after, Greta Thunberg, now 21, began school striking in Sweden. That fall, the Sunrise Movement went viral after occupying Representative Nancy Pelosi’s office and demanding climate legislation. They started attending global climate conferences and it seemed like the adults might be listening.

Aru Shiney-Ajay, now 26 and the executive director of the Sunrise Movement, withdrew from Swarthmore College in 2019 to organize full time. She moved into a Philadelphia house with seven other people and slept on a mattress on the floor.

But then, the coronavirus pandemic arrived in the United States and the dizzying ramp-up of the youth climate movement seemed to stall.

Much of the movement went from mass marches to the internet, where even younger members of Gen Z were ready and waiting. From her home in Oakland, Calif., Elise Joshi, now 22, began using her social media prowess to amplify some of her peers’ climate causes. She eventually took over a new nonprofit organization — Gen-Z for Change — that uses online campaigns to fight liquefied natural gas terminals on the Gulf Coast and support union strikes at auto manufacturers in Detroit.

But as the activists grew up, the tactics that once gave their movement star power — mass protests and school strikes — began to feel stale. Groups started to get more disruptive: members of Just Stop Oil began throwing cans of soup on famous paintings; Climate Defiance began crashing political events. (In September, they interrupted an interview with Vicki Hollub, an oil company executive, during a New York Times climate conference.)

They were disenchanted by the United Nations Climate Change Conference, this year held in Baku, Azerbaijan, where hopes were dashed for more than $1 trillion in climate financing to materialize for developing nations. Five years after she sailed solo across the Atlantic to attend climate talks in London, Greta Thunberg boycotted COP29, as this year’s conference was called.

Zero Hour sent Jamie Minden, the group’s senior director of global organizing, who at 13 was lying in her bed staring at the ceiling when she decided to devote her young life to fighting the climate crisis. But almost a decade later, Ms. Minden, now 21, knew to brace herself.

COP29 was a disappointment, she said, if not a death sentence for poor nations.

And in the U.S., things were not going quite as well under a Democratic administration as they’d hoped: President Biden has permitted major fossil fuel projects and the U.S. is now the world’s top oil producer; global carbon emissions are on track to hit historic levels in 2024.

On the day Mr. Biden dropped his re-election bid, Gen-Z for Change quickly endorsed Vice President Kamala Harris to replace him, as did Climate Defiance. Sunrise Movement has only endorsed one presidential candidate — Senator Bernie Sanders in 2020 — but helped call four million voters on behalf of Ms. Harris. Zero Hour did not endorse a candidate because of the group’s opposition to the war in Gaza. Some of the nine youth climate activists who spoke to The Times said they voted for Jill Stein, the third-party candidate, in protest.

But now they again have a clearer adversary in Mr. Trump. The stakes are high: 2024 will again be the hottest year on record, and scientists warn that the world is well on its way to locking in 1.5 degrees Celsius of warming above preindustrial levels.

Mr. Trump has called climate change a hoax, promised to again withdraw from the Paris Agreement, and he’s working to appoint key federal leaders that support an expansion in oil and gas drilling and overturning environmental rules. Project 2025, which Mr. Trump has not endorsed but could serve as a blueprint for his administration, has proposed eliminating environmental justice offices.

Leah Thomas, 29, made a social media post in 2020 that popularized the term “intersectional environmentalist.” Her platform was based on links between racial and environmental justice, looking at “the ways in which injustices happening to marginalized communities and the earth are interconnected.” She worried that disagreements over politics, especially over the war in Gaza and how to address fossil fuels that are warming the planet, had splintered the movement.

But Mr. Trump could again be a unifying force as activists refocus their movement at the local and state level. On Tuesday, members of climate groups, including Fridays for Future, held a rally and then occupied a room in the New York State Capitol building to push Governor Kathy Hochul to sign the Climate Change Superfund Act. The proposal, like one passed this summer in Vermont, would require polluters like oil and gas companies to pay billions per year that would be used to cope with damage from extreme weather events.

Whatever the next round of youth climate activism looks like, youth activists overwhelmingly agree that it will be about more than just climate.

“We’re not just the youth climate movement, but the youth climate justice movement,” said Keanu Arpels-Josiah, a 19-year-old core organizer for Fridays for Future USA. “That reframing is really key.”