This story was originally published by Inside Climate News and is reproduced here as part of the Climate Desk collaboration.

Montana Republican lawmakers have passed legislation that bars state agencies from considering climate change when permitting large projects that require environmental reviews, including coal mines and power plants. Gov. Greg Gianforte signed the bill last week, marking what could be considered the nation’s most aggressive anti-climate law.

Under House Bill 971, Amanda Eggert reports for the Montana Free Press, the Montana Department of Environmental Quality and other state regulators can’t consider greenhouse gas emissions and climate impacts when conducting environmental reviews for large projects. The move builds off a decade-old state law that already banned the state from considering “actual or potential impacts that are regional, national, or global in nature” in such reviews.

The law comes as a Montana judge weighs a case brought by 16 youth plaintiffs who are suing the state government for its pro-fossil fuel energy policies, which they argue violates their right to a “clean and healthful environment” as guaranteed by Montana’s 50-year-old constitution. The hearing for that case is set to begin next month.

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Proponents of Montana’s new law, including its sponsor, Rep. Josh Kassmier, argued the legislation was necessary to restore authority over setting policy to state lawmakers after a district judge revoked a permit back in April for a proposed natural gas power plant that state regulators had already approved.

But the measure was met by fierce opposition from environmentalists, who accused the Republican-led Montana Legislature of “hiding its head in the sand” and argued that the majority of Montanans believe in human-caused climate change and want to take meaningful action to address it. A 2022 poll conducted by Colorado College found that nearly 60 percent of Montanans believe in climate change and want to address it, including by transitioning to renewable energy. Of the more than 1,000 comments submitted by local residents on House Bill 971, a whopping 95 percent opposed it.

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“Our families are already suffering from an increase in the number of sweltering summer days, longer wildfire and smoke seasons, and historic drought,” Winona Bateman, executive director of Families for a Livable Climate, told the Montana Free Press. “I am not sure how Gov. Gianforte imagines we will do our part to address these growing impacts, or pay for them, if we’re not working to eliminate the root cause.”

Montana’s climate has changed notably over the past century, according to the Environmental Protection Agency, leading to snowpacks melting earlier in the year, more frequent heat waves and increased risk of wildfires. In fact, Montana’s own 2015 climate assessment found that the state’s annual average temperatures have increased between 2 and 3 degrees Fahrenheit from 1950 to 2015, with winter and spring temperatures rising upwards of 3.9 degrees. That report also found that between 1951 and 2010, the state’s average winter precipitation decreased by roughly an inch and the number of days exceeding 90 degrees Fahrenheit in any given year grew by an average of 11.

But despite those impacts, Montana Republicans have fought tirelessly to thwart policies that could threaten the bottom line of coal, oil and gas companies in the state. The Treasure State—a nickname referring to the wealth of minerals found in Montana’s mountains, including coal—has long benefited from a bustling fossil fuel industry. The Bakken formation, one of the largest onshore oil and gas fields in the United States, lies partially in eastern Montana. The state also contains the largest recoverable coal reserves in the U.S., with six coal mines still active and nearly half the state’s electricity coming from coal-burning power plants.

Several GOP state lawmakers also have close ties to the fossil fuel industry. Both Montana Rep. Gary Parry, a member of the House Natural Resources Committee, and recently retired state Sen. Duane Ankney worked for the coal industry before serving in office. U.S. Rep. Ryan Zinke, the Montana Republican who served as Secretary of the Interior under former President Donald Trump, was also a board member of the oil pipeline company QS Energy before he helped facilitate oil and gas development on federal lands for the Trump administration.

Still, the bill that Gov. Greg Gianforte signed into law last week could set a new precedent for anti-climate policy. Not since North Carolina passed its 2012 law, which prohibited government agencies from using anything but historical data on sea level rise when drafting development policy, has a state legislature so aggressively sought to squelch modern climate science. By the time North Carolina’s law passed, opponents had successfully weakened it so that agencies were only banned from considering scientific climate projections for four years. Montana’s law contains no such amendment and extends to all climate-related impacts, not just sea level rise.

Several other red states have introduced or passed legislation that also limits government consideration of climate change, but mostly in public education and investing. Texas passed a law that bars the state from doing business with financial firms that have divested from fossil fuel companies for climate reasons, with state lawmakers now hoping to extend that ban to climate-conscious insurance companies. Nearly two dozen red states have passed or are considering similar actions. 

Ohio Republican lawmakers are considering legislation that would force colleges to teach “both sides” of the debate over whether human-made climate change is real, despite the fact that 99.9 percent of scientific literature agrees that burning fossil fuels is accelerating global warming at an unprecedented rate. Tennessee and Louisiana have already passed similar laws.

North Carolina’s law could also conflict with federal policy, including the EPA’s recent draft rule that would require coal-fired power plants, along with some natural gas plants, to use new technologies to capture 90 percent of their carbon emissions by 2038.

In a statement to Montana Free Press, Gianforte spokesperson Kaitlin Price said the new law would allow state agencies to analyze greenhouse gas emissions “if it is required under federal law or if Congress amends the Clean Air Act to include carbon dioxide as a regulated pollutant.” But Congress did just that last year, when it passed the Inflation Reduction Act, which amended the Clean Air Act’s Title VI to include new sections on clean vehicles, greenhouse gas emissions and port pollution.

“There’s a tapestry that is woven throughout the fabric of the Clean Air Act under this legislation that makes it abundantly clear it is EPA’s responsibility to address climate pollution,” Vickie Patton, general counsel at the environmental advocacy nonprofit Environmental Defense Fund, told Bloomberg Law. That includes “greenhouse gases or air pollutants.”