Mica, aged 15, learned about climate change when he was just four, when his parents showed him the documentary Chasing Ice. “I understood it more than my parents thought I would,” he testified in a groundbreaking trial on Tuesday. “I just knew something bad was happening, but I didn’t know exactly what it was.” Mica came home from the film crying, he recalled. His parents helped him send a letter about the climate crisis to Senator Jon Tester, a rare Democrat in office in Mica’s home state of Montana. But Tester’s office merely sent an automated response. Since then, Mica told the first judicial district court of Montana, he has learned more about climate change in school and by reading scientific articles, and has become involved in advocacy to combat it. He has also seen its effects firsthand. Mica is one of the 16 youth plaintiffs in the 2020 lawsuit Held v Montana, which is being heard in the state capital, Helena, this week. The challengers allege that state officials have violated their constitutional rights to a healthy environment. The trial, which began on Monday, marks the first ever constitutional climate trial in US history. A lover of the outdoors, Mica, who lives in Missoula, Montana, said he was frequently bothered by smoke from wildfires. This makes it hard to go for runs, something the young plaintiff has enjoyed since he was five. When he can’t train due to the smoke, Mica said, he feels “trapped”. “I can’t get my mind off things,” he said. In 2020, Mica contracted Covid and was forced to isolate from his family in his basement. Because of the intensely hazy conditions, he could not go outside. “I’m a prisoner in my own home,” Mica, who this spring was diagnosed with asthma, wrote in a poem at the time, which he read on the stand. The fires have in recent years moved close to Mica’s family home. “A couple years ago we had a small fire start about a mile above our house,” he said in court. “I packed the important stuff just in case we got an evacuation notice,” he said, noting that the helicopters circling overhead and firefighters patrolling the area made the experience “pretty scary”. In the future, Montana’s wildfires will only get worse as heat and dry conditions become more common, according to Earth scientist Cathy Whitlock, a professor emerita of Earth sciences at Montana State University who served as an expert witness for the plaintiffs earlier in the day. Whitlock, who led Montana’s 2017 climate assessment and has co-authored several climate other reports for the state, explained that Montana’s average temperatures (according to Noaa data) have risen by an average of 0.2 degrees Fahrenheit per decade since 1900. Since 1970, the rise has been even more drastic, at 0.53 degrees per decade. “And the rate is increasing,” she said. All that warming, Whitlock said, fuels not only wildfires – which spark more easily in hot, dry conditions – but also drought, snowpack loss and extreme heat. These trends are only expected to become more dramatic as the climate crisis progresses. “The plaintiffs by the end of the century are going to be experiencing much warmer conditions than now,” Whitlock said. Tensions ran high as Whitlock was cross-examined by Thane Johnson, an attorney representing the state. The court case specifically alleges that part of the Montana Environmental Policy Act, which prevents the state from considering how its energy economy may contribute to climate change, runs counter to the state’s constitutional requirements to provide a “clean and healthful” environment. Johnson asked Whitlock about the state’s non-energy sources of emissions, such as agriculture, which would not be affected if the Montana Environmental Policy Act was overturned. Further, he asked if Montana could tackle the climate crisis on its own. Whitlock agreed that every sector in Montana must cut its emissions, and that the climate crisis is a global problem. But slashing planet-warming pollution from the energy sector, she said, would help secure a livable future. “All areas have to do their part,” she said. Johnson became visibly agitated while cross-examining Whitlock, earning him an admonishment from the judge. “You need to settle down just a little bit, Mr Johnson,” Judge Kathy Seeley said.