On the heels of a dire government report published last month about climate change and its devastating impacts, many cities and states are scrambling to find ways to curb the greenhouse gas emissions that threaten their air quality, not to mention their economies.

As is often the case, California is leading the charge, yesterday becoming the first state to mandate that mass transit agencies purchase fully electric buses only beginning in 2029, and that public transit routes be populated by electric buses alone by 2040.

The new rule is expected to require the production and purchase of more than 14,000 new zero-emission buses.

Mary Nichols, chair of the California Air and Resource Board (CARB) that voted unanimously to make California the first state with such a commitment, told the outlet Trucks.com earlier this month that California has “to push standards that are more progressive” than the federal government because of the state’s chronic air pollution, which is linked to asthma and heart disease, among other things.

The move is reportedly the result of several years of CARB’s work with industry and public-health groups, and it flies in the face of moves by the Trump administration to push for lower fuel efficiency standards and to promote the use of fossil fuels.

Indeed, the Trump administration has questioned from the outset how much the U.S. is responsible for cutting back emissions, and the newest government report seemingly didn’t alter anything for the President. Asked last month about the government’s findings that, unchecked, global warming will have catastrophic implications for the U.S. economy, he said, “I don’t believe it.” He added: “People like myself, we have very high levels of intelligence but we’re not necessarily such believers.”

Instead of wait on the administration to change its mind, California’s new Innovative Clean Transit rule will force California’s public bus lines — many of which currently run on natural gas or diesel fuel — to shift to either electric power or hydrogen fuel cells.

The move could be a boon for electric bus companies like Proterra, a 14-year-old, Burlingame, Ca., company that has raised roughly half a billion dollars from investors to build its zero-emission, battery-electric buses. It could also potentially help the publicly traded Chinese automaker giant BYD, which, as TC has reported, has been on a partnership spree with cities across China to electrify their public transportation systems and is now extending its footprint across the globe.

The new ruling is not the only line of attack that California is adopting. As The Hill notes, earlier this year, California also voted to become the first state to mandate new homes be retrofitted with solar panels. In September, Governor Jerry Brown signed a bill that will require the state to transition to a 100 percent renewable energy electric grid by 2045.

CARB has also worked to advise the U.S. Environmental Protection Agency, which last month announced what it called its Cleaner Trucks Initiative. EPA officials say that via the initiative, the agency plans to revise truck pollution standards in a way that lowers their nitrogen oxide emissions while also doing away with requirements that the industry has complained are financially onerous.

As reported by the L.A. Times, despite the announcement, no one yet knows if the EPA is planning more stringent emissions limits or anything as strict as the 90 percent reduction in nitrogen oxide pollution that CARB has said is needed to clean smog to health standards.