Inside the First Youth-Led Climate Lawsuit to Go to Trial

“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 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 Peter 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 is currently the case.

“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.”