HELENA, Montana—At the close of the final day of their lawsuit against Montana for its failure to rein in development of fossil fuels in the state and slow climate change, all but one of the 16 young plaintiffs filed out of the Helena courtroom with their lawyers, family members and other supporters. Grace Gibson-Snyder stayed, helping the judge’s scheduling clerk, Farrah Looney, collect the beige and blue cushions that had padded the uncomfortable wooden benches where the plaintiffs sat during the trial.

“You don’t have to help,” said Looney.

 “I know,” responded Grace, who smiled as she continued collecting cushions, unwilling to leave until she’d done what she could to clean up.

It was a fitting scene to close the first youth-led climate trial in the United States last Tuesday. Held v. Montana was, on its face, about a very specific statutory provision buried in Montana’s Environmental Policy Act that forbids the state’s environmental agency from assessing the climate impacts of fossil fuel extraction within the state. But the central tension of this lawsuit was much larger.

Three years earlier, the plaintiffs filed their complaint against Montana’s entire executive branch, alleging that by prioritizing the permitting of fossil fuel extraction, their state was betraying their right to a “clean and healthful environment” as guaranteed in the state’s constitution. The plaintiffs, ages 5 to 22, argued that, even in the face of this global issue, small-scale actions from state governments matter. The state argued the opposite: that if Montana can’t fix the problem of climate change by itself, the courts shouldn’t hold it responsible to redress a harm it can’t correct on its own.

Despite the state’s best attempts to have the case thrown out, the plaintiffs had made it to court, where they sat in front of Judge Kathy Seeley for seven long, disorienting days as the two sides argued about two completely different ways of seeing the world.

Over the first five days of the trial, the plaintiffs’ attorneys carefully shaped their case through the stories and testimony of 21 witnesses—eight experts and 14 youth plaintiffs, two of whom were represented by their father. Each expert, from climate scientists to energy analysts and public health experts, painstakingly demonstrated in varying ways how climate change was impacting the humans and ecosystems of Montana, and each ended by reminding the court that these changes could be prevented or ameliorated by intentional action. Many of them repeatedly returned to a quote from a 2021 report from the United Nations Intergovernmental Panel on Climate Change stating, “Every ton of CO2 matters,” which they used to support their argument that any reduction in Montana’s emissions would make a difference, both within the state and globally.

Each youth plaintiff, whose stories of loss and grief were sandwiched between expert testimony, ended their time on the stand describing how they would feel if they won the lawsuit: hopeful.

“I would feel relief and joy, that what we’re doing matters,” said 18-year-old Kian Tanner, “that when we speak out, when we create action, we can create positive change in the world.”

The tension between the two sides was especially apparent while the defense was cross-examining the plaintiffs’ expert witnesses, attempting to prove that any solution would need to be far bigger than Montana could provide.

“If Montana just stopped emitting CO2 today, if every farmer threw in the keys to their tractors, if I even handed you my keys, would you agree that would not have an impact on local GHC, I mean GHG [greenhouse gases]?” asked Assistant Attorney General Thane Johnson, who repeatedly mixed up acronyms during the trial.

“That would be a good step forward in trying to bring the climate system into equilibrium,” responded Cathy Whitlock, a paleoclimatologist and lead author of the 2017 Montana Climate Assessment.

The attorneys asked a similar question of Steven Running, a climate scientist and member of the team that won the Nobel Peace Prize for the 2007 IPCC report: if Montana stopped emitting greenhouse gases, would that prevent the plaintiffs from being harmed by climate change?

“We can’t tell. What’s been shown in history over and over is that when a significant social movement is needed, it’s often started by one or two people,” said Running, who lives in Missoula. “If our state did this, we can’t tell how many other states would decide ‘That’s the right thing to do, and we’re going to do it too.’ ”

In her written expert report for the defense, Judith Curry, a climatologist who disputes the scientific consensus that human activity is the primary driver of climate change, argued that the plaintiffs’ concerns about climate change are greatly exaggerated and that emissions from fossil fuels generated in Montana are minuscule compared to global emissions and do not directly influence Montana’s weather and climate. However, as Curry wrote on her website, on the fourth day of the trial, she received a call from the state’s lawyers saying they were “letting [her] off the hook.” She did not testify and her expert report was not entered into evidence.

Before Curry’s testimony was canceled, Peter Erickson, a climate policy expert who specializes in climate-related emissions accounting, responded to Curry’s written report during his testimony. “You can’t say an individual source [of CO2] isn’t important because the problem is so big. To say that says more about the size of the problem than to say anything meaningful about the action,” said Erickson. “Montana’s contribution [to greenhouse gas emissions], is nationally and globally significant. What Montana does matters.”

On day five of the plaintiffs’ case, energy transition expert Dr. Mark Jacobson told the judge that a rapid transition to renewable energy was technically and economically feasible for Montana, but the move to wind, water and solar energy must happen at a much faster pace than it is currently

“The main barrier to energy transition is that we need collective willpower,” he said. “That requires individuals, state governments and national governments to work toward this goal.”

The defense had a much narrower argument: the lawsuit is about a procedural statute—the prohibition of DEQ considering climate impacts when permitting oil and gas development—that, even if it were changed, would not help the plaintiffs, as the legislature has not given Montana’s Department of Environmental Quality (DEQ) the authority to deny permits. And even if Montana were to stop emitting, there would be minimal impact globally.

The argument was so simple that the defense presented its case with three witnesses over the course of a single day. Two DEQ employees were emphatic that they could not do anything to change greenhouse gas emissions in the state because they can’t deny permits to fossil fuel projects and they don’t have authority over other sectors, like energy development, transportation or agriculture. 

Economist Terry Anderson, who specializes in “free-market environmentalism,” attempted to put Montana’s emissions in global context but, during cross-examination, became flustered when the origins of his data were called into question. In a moment of courtroom drama, Anderson claimed that his numbers about Montana’s 2022 emissions were from the U.S. Energy Information Administration website before the plaintiffs’ attorney, Phil Gregory, presented a printout from the website displaying that data was not, in fact, published on the EIA website.

During closing arguments, the plaintiffs’ lead attorney, Nate Bellinger, argued that the right to a clean and healthful environment is as essential as other basic human rights, and required courageous judicial intervention. He asked Seeley to declare that “a stable climate system is fundamental to the protection of the right to a clean and healthful environment,” establish a constitutional standard of 350 parts per million of atmospheric CO2 as a target to guide state energy permitting, and to declare as unconstitutional the permitting limitations placed on the DEQ, which is currently unable to deny permits for fossil fuel development due to the climate-warming emissions they would produce.

Responding on behalf of the state, Assistant Attorney General Michael Russell said the plaintiffs are attempting to end run the legislature by asking the courts to force state agencies to make decisions that they’re not authorized to make and had turned what should be a procedural matter into “a weeklong hearing of political grievances that properly belong to the legislature and not a court of law.”

In the coming weeks, both sides will file their own proposed findings of fact and conclusions of law—a list of agreed-upon and disputed facts, as well as lawyers’ interpretations of applicable law intended to help the judge with her decision—commonly part of a bench trial. Once those are complete, Judge Seeley will wade through the hundreds of pages of evidence presented during the trial and issue her decision.

In the meantime, the plaintiffs are returning to their lives. One is working with a Montana environmental nonprofit, another is preparing to go to Kenya for the Peace Corps and yet another is tapering off his training for a half-marathon—a celebration of the running habit that has helped him process his anxiety about climate change. No matter the outcome of this case or how small their actions may seem compared to this global issue, they’re going to keep trying to change the trajectory of climate change in the state they love.

Correction: A previous version of this story misstated Dr. Mark Jacobson’s first name.