AS MASSACHUSETTS HITS a climate crossroads, the state’s top law enforcement official is warning that the gas companies are not on track to meet ambitious climate commitments — and urged regulators to impose penalties if the companies don’t step up their efforts to transition away from planet-warming fossil fuels.

Attorney General Andrea Campbell and her team, along with leading environmental advocacy groups and the Healey administration’s Department of Energy Resources in separate briefs, admonished the utilities in new filings before the Department of Public Utilities, telling the regulators that the state’s five gas companies turned in “completely inadequate” climate compliance plans last year.

The gas companies, the AG contends, continue to assert “business-as-usual” plans that are “sidestepping” the DPU’s push for the companies to lay out the costs of the clean energy transition without saddling ratepayers with bloated bills and how they will meet emissions reduction mandates by weaning customers off natural gas.

If the gas companies don’t submit substantially reworked climate compliance plans, the DPU should get tough and impose fines — something that “sends a strong message” and “is a reasonable Department action,” according to the AG.

The latest front in the battle with the state’s utilities — chiefly over the use of natural gas and the supply and distribution network — is a crucial pivot point in whether Massachusetts will be able to cut greenhouse gas emissions by 85 percent compared with 1990 levels by 2050. The building sector represents about 36 percent of greenhouse gas emissions in the state, mostly from old homes and buildings that rely on natural gas as the primary source for heating and cooking.

The state’s ability to slash its emissions at the scale required will depend, in large part, on whether it’s able to electrify those buildings or leverage geothermal energy for heating and cooling while decommissioning gas pipes. Massachusetts will have to manage the cost of that transition while Bay State customers already pay some of the nation’s highest energy bills.

Achieving that feat rests on a central tension: Getting Eversource, National Grid, Unitil, Berkshire Gas, and Liberty to move away from how they currently make money — providing gas to customers.

“Addressing affordability while maintaining reliability for customers and supporting the state’s decarbonization goals is a delicate balancing act, and our Climate Compliance Plan is strategically aimed at advancing those sometimes-disparate goals,” William Hinkle, a spokesperson for Eversource, said in a statement. “Through initiatives like our first-in-the-nation networked geothermal pilot in Framingham and our upcoming electrification demonstration projects, we are constantly pursuing innovative solutions to help the commonwealth strike the appropriate balance between those goals while keeping customer choice and affordability front of mind.”

National Grid also defended its climate compliance plan. Brendan Moss, a spokesperson for the company, said in a statement that its plan takes an “all-of-the-above approach” that is intended to “support emissions reductions while enabling efficient investment, optimizing the use of existing energy infrastructure, and maintaining safe and reliable service for customers during the transition.”

Unitil and Liberty declined to comment, and Berkshire Gas did not immediately respond to a request for comment.

The investor-owned gas companies filed their first ever climate compliance plans last year in response to the DPU’s so-called Future of Gas strategy that launched in 2020 to provide a roadmap for achieving decarbonization while minimizing the effects on ratepayers. That probe led the DPU to issue a landmark order, which required the utilities to evaluate non-gas alternatives that would render additional gas infrastructure investments unnecessary.

It also required the companies to submit the climate plans every five years, starting in 2025, that detail how they are reducing emissions in line with state goals. But based on the fiery responses from the AG, Healey administration, and environmental groups, the process of working with the gas companies to navigate the transition away from gas appears less collaborative than ever.

The utilities have until May 5 to file their response, before the DPU gets to weigh in.

Campbell’s office lambasted the utilities’ plans at practically every turn in its brief to regulators, writing that the companies neglected to think through how to reduce their emissions tied to customer gas usage, failed to spell out the total investment needed to meet state climate goals, pinned the bulk of their climate efforts on existing programs like Mass Save, and risked shouldering a shrinking pool of customers with even greater gas system costs.

Those omissions, according to the AG’s filing, are “intentional” — and the companies are trying to avoid accountability in a “clumsy attempt” to argue that some of the requirements of the climate plans as laid out by the regulators were nonbinding suggestions.

The AG also criticized the gas companies’ apparent interest in alternative fuels like “renewable natural gas” and hydrogen, even though the DPU rejected a similar pitch to embrace those technologies from the utilities in the past.

The environmental groups, including the Conservation Law Foundation, Environmental Defense Fund, and Sierra Club, were even less forgiving, calling on the DPU to flat out reject the gas companies’ climate compliance plans, order new plans be submitted within 90 days, and issue financial penalties if the utilities fail to do so.

The Healey administration, through a brief filed by the Department of Energy Resources, piles on the utilities, too, urging the DPU to reject the climate compliance plans because they are “inactionable and unenforceable.”

A core piece of the fight over the gas companies’ climate compliance is whether the utilities are obligated to provide gas service to any customer who may want it.

The companies argued in their plans that they have an “obligation to serve,” which in their view means that any customer who does not want an alternative source of heat must be served with gas and can effectively block a neighborhood-level electrification or geothermal project from proceeding. The AG and advocates pushed back, asserting that customers can be switched to other heating sources so long as adequate substitutes for gas are put in place.

Where the DPU lands on that part alone has significant stakes for the future of the state’s clean energy transition.

“If we can’t get the obligation to serve right,” Kyle Murray, Massachusetts program director at the environmental nonprofit Acadia Center, said in an interview, “we’ve lost the whole game on achieving a managed, timely, and cost-effective gas transition.”