Some state legislators can't or won't come to grips with the reality that coal is not the fuel of the 21st century.

Like all states, Pennsylvania is required to devise a Clean Power Plan in accordance with new federal regulations. The Wolf administration is doing so as federal appeals courts deal with challenges to the regulations.

The federal standard calls for Pennsylvania to reduce carbon emissions from 2005 levels by 32 percent by 2030, with measurable progress by 2022. How to achieve that goal is up to the state.

That inevitably means reduced use of coal to produce electricity — a movement that already is well underway and will continue because of market forces rather than regulations. Pennsylvania utilities already have shuttered a half dozen coal-burning plants while converting others to natural gas, which produces less than half as much carbon pollution as coal for comparable amounts of energy. Other coal plants are being converted to gas, and renewable fuels also are on the rise.

But some legislators want to defy market forces and delay implementation of the Clean Power Plan and improved drilling regulations making gas production as environmentally sound as possible.

One bill would delay the Clean Power Plan by at least a year. Another would, in effect, restart a regulatory process regarding new gas-drilling regulations that has been underway for years. A third bill would create a self-perpetuating loop under which legislators could block any regulation that they don't like. Another bill would allow certain industrial entities to opt out of state-mandated energy-efficiency programs.

Mr. Wolf should veto any legislation that slows the state's progress toward a cleaner energy and sounder environmental future.