A judge in the US Republican-dominated state of Montana ruled on Monday in favor of a group of young climate activists who accuse state agencies of violating their constitutional right to a clean and healthy environment.

The 16 plaintiffs, who range in age from 5 to 22, argued that the state allowed fossil fuel development without considering its impact on the climate, harming them both mentally and physically.

The trial is believed to be the first of its kind in the US, and the ruling is expected to boost the chances of climate activists appealing to courts to make a case for the environment.

What happened in the court?

During the two-week trial in June, attorneys for the youths presented evidence that the increase in carbon dioxide emissions was causing temperatures to rise, droughts and wildfires to increase and snowpack to slim down. Attorneys argued the changes were harming the youths' physical and mental health.

Montana is a major producer of coal, oil and gas that is shipped elsewhere. It is also home to pipelines and other infrastructure needed to ship those fuels.

The state had argued that Montana's carbon footprint was insignificant in the grander scheme, stressing that even if the state completely halted its CO2 emissions, there would be no sizeable impact.

District Court Judge Kathy Seeley deemed the state policy for evaluating requests for fossil fuel permits unconstitutional. The policy doesn't allow agencies to assess the impacts of greenhouse gas emissions.

The judge wrote in the ruling that "Montana's emissions and climate change have been proven to be a substantial factor in causing climate impacts to Montana's environment and harm and injury" to the youth.

However, as the Republican-dominated state legislature is responsible for working out how to bring the policy into compliance, the chances for an immediate impact are slim.

'Huge win' for youth and climate

Judge Seeley argued in her over 100-page ruling that "plaintiffs have a fundamental constitutional right to a clean and healthful environment, which includes climate as part of the environmental life-support system."

Julia Olson, an attorney with environmental group Our Children's Trust, celebrated the ruling as a "huge win for Montana, for youth, for democracy and for our climate."

"More rulings like this will certainly come," Olson predicted. "As fires rage in the West, fueled by fossil fuel pollution, today's ruling in Montana is a game-changer that marks a turning point in this generation's efforts to save the planet from the devastating effects of human-caused climate chaos."

A spokesperson for the Montana attorney general's office called the ruling "absurd," and said the state planned to appeal.

rmt/nm (AFP, AP)