HELENA, Mont. — (AP) — Montana's Supreme Court on Wednesday upheld a landmark climate ruling that said the state was violating residents' constitutional right to a clean environment by permitting oil, gas and coal projects without regard for global warming.

The justices, in a 6-1 ruling, rejected the state's argument that greenhouse gases released from Montana fossil fuel projects are minuscule on a global scale and reducing them would have no effect on climate change, likening it to asking: "If everyone else jumped off a bridge, would you do it too?"

The plaintiffs can enforce their environmental rights "without requiring everyone else to stop jumping off bridges or adding fuel to the fire,” Chief Justice Mike McGrath wrote for the majority. “Otherwise the right to a clean and healthful environment is meaningless.”

Only a few other states, including Hawaii, Illinois, Pennsylvania, Massachusetts and New York, have similar environmental protections enshrined in their constitutions.

The lawsuit filed in 2020 by 16 Montanans —who are now ages 7 to 23 — was considered a breakthrough in attempts by young environmentalists and their attorneys to use the courts to leverage action on climate change.

“This ruling is a victory not just for us, but for every young person whose future is threatened by climate change,” lead plaintiff Rikki Held said in a statement Wednesday.

During the 2023 trial in state District Court, the young plaintiffs described how climate change profoundly affects their lives: worsening wildfires foul the air they breathe, while drought and decreased snowpack deplete rivers that sustain farming, fish, wildlife and recreation and affect Native traditions.

Going forward, Montana must "carefully assess the greenhouse gas emissions and climate impacts of all future fossil fuel permits,” said Melissa Hornbein, an attorney with the Western Environmental Law Center and attorney for the plaintiffs.

Republican Gov. Greg Gianforte said the state was still reviewing the decision, but warned of “perpetual lawsuits that will waste taxpayer dollars and drive up energy bills for hardworking Montanans."

“This decision does nothing more than declare open season on Montana’s all-of-the-above approach to energy," he said, which promotes using both fossil fuels and renewables.

A day earlier, Gianforte held meetings on how the state can increase energy production, which involved energy suppliers, large energy consumers, public utility companies, transmission stakeholders and legislators.

Incoming Senate President Matt Regier and House Speaker Brandon Ler, both Republicans, joined Gianforte in alleging the justices were overstepping their authority and had strayed into making policy.

"Judicial reform was already a top priority for Republican lawmakers,” Regier and Ler said, warning the justices to “buckle up.”

Montana courts have blocked or overturned numerous laws passed by Republicans in the 2021 and 2023 legislative sessions as being unconstitutional, including laws to limit access to abortion.

In seeking to overturn the District Court ruling, the state had argued the plaintiffs should be required to challenge individual fossil fuel development permits as they’re issued — which would have involved trying to challenge even smaller amounts of emissions.

Carbon dioxide, which is released when fossil fuels are burned, traps heat in the atmosphere and is largely responsible for the warming of the climate. June brought record warm global temperatures for the 13th straight month, according to European climate service Copernicus. The streak ended in July.

Montana's Constitution requires agencies to "maintain and improve" a clean environment. A law signed by Gianforte last year said environmental reviews may not consider climate impacts unless the federal government makes carbon dioxide a regulated pollutant. The Montana Supreme Court's ruling found that law to be unconstitutional.

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