Massport has a $1 billion plan to cut climate pollution. Critics say it’s nowhere near enough.

In one of the state’s largest efforts to curb carbon emissions, the Massachusetts Port Authority unveiled plans Thursday to spend $1 billion over the coming decade to reduce its contribution to the pollution that causes climate change.

The officials who operate Logan International Airport, Flynn Cruiseport, and the Paul W. Conley Terminal — among other airports and institutions — released what they’re calling a roadmap to effectively eliminate emissions under their control by 2031, the 75th anniversary of the authority’s founding.

“This is a real plan, tied to real actions, without smoke and mirrors,” said Lisa Wieland, the chief executive of Massport. “This isn’t going to be easy … but we need to reduce the impact on the communities that surround us. The cost of doing nothing isn’t an option.”

When fully implemented, the plan would mean a reduction of about 110,000 metric tons of carbon emissions a year, the equivalent of removing roughly 24,000 cars from the road.

Environmental advocates praised Massport for being among the largest state agencies to release a plan that seriously grapples with what it can do to substantially reduce its contribution to climate change.

“This is the kind of analysis and planning that all public and quasi-public entities should be doing,” said Elizabeth Turnbull Henry, president of the Environmental League of Massachusetts.

She said she hoped Massport would become “a laboratory for climate innovation.”

“Massport could be one of the best places in the world to pilot technologies to transform aviation and other hard-to-decarbonize transportation sectors,” she said.

Yet critics noted that Massport’s plan relies heavily on carbon offsets to achieve so-called net-zero emissions in the near term and only addresses the pollution under Massport’s direct control — not the much larger sources of greenhouse gases, such as the planes that fly in and out of Logan or the cruise and cargo ships that dock at its terminals.

Under the plan, which remains more of a sketch than a blueprint, just 12.5 percent of Massport’s emissions would be subject to reductions. Of that pollution, 40 percent would require offsets to achieve net zero. That means the authority will have to purchase pollution credits or invest in programs that reduce emissions elsewhere.

Massport officials said they intend to stop producing emissions entirely by 2040, meaning the authority would no longer require offsets to be carbon neutral.

Some state officials and environmental advocates said they were skeptical of Massport’s plan, noting that the quasi-public agency is obligated under the state’s new climate law to effectively eliminate its emissions by 2050.

“The effort lacks imagination,” said state Senator Mike Barrett, a Lexington Democrat and one of the authors of the climate law that took effect last year. “So far, there’s no indication [Massport is] hungry to move into the vanguard, become a role model.”

Massport’s plan, which must be approved by its board, hinges on significant changes to how the agency heats its terminals at Logan and other buildings, produces hot water, and otherwise uses energy.

That includes updating its gas-powered central heating plant at Logan; replacing its large fleet of diesel trucks, shuttle buses, and other ground-support equipment with those that draw power from electricity; installing energy-efficient lighting across all its facilities; and generating more power from on-site renewable energy sources, such as solar panels.

Those changes will impose significant costs as the agency continues to suffer from the pandemic and faces an uncertain future. Last fiscal year, as passenger traffic at Logan plummeted and few cruise ships visited Boston, Massport earned little more than $650 million in revenue — a decline of more than a quarter from before the pandemic.

“It will be more of a challenge,” said Jennifer Mehigan, a spokeswoman for Massport, noting that this fiscal year’s projections for passenger traffic at Logan are about 40 percent lower than in 2019 — and that was before the war in Ukraine led to a surge in fuel costs.

The plan remains a broad outline and doesn’t specify how it will achieve its goals, such as generating carbon-free heat across Logan’s sprawling terminals. Given that many decisions have yet to be made, environmental advocates said it was difficult to assess whether Massport’s plan was sufficient to live up to Wieland’s promises.

“The content we have seen to date is not a clear plan, so I have reservations on what emissions reductions they will actually achieve,” said Kyle Murray, a senior policy advocate at the Acadia Center, an environmental advocacy group in Boston.

He urged Massport officials to be more ambitious and do more as soon as possible to create their own renewable energy and storage technology, sign power purchase agreements with producers of clean energy, and accelerate programs to replace fossil fuels with electricity.

A plan that relies on fewer offsets over the coming decade would be more credible, Murray and others said.

“The devil will be in the details where offsets are concerned,” said Cammy Peterson, director of clean energy at the Metropolitan Area Planning Council, noting it’s often hard to accurately measure the benefits of offsets compared with actual reductions.

Others said they hope officials will do more to consider how to reduce the 87.5 percent of its emissions that aren’t included in its plans.

For example, Massport could do more to compel vendors at the airport and elsewhere to reduce their emissions; invest more in developing so-called sustainable aviation fuels; make it easier to get to their terminals on public transportation or in shared rides; and provide incentives for the speedier electrification of the taxi and ride-for-hire industry.

Massport officials said they plan to do all those things, including taking other steps to reduce their overall emissions, such as enabling cruise ships to draw power from shore rather than from their idling engines, which is a large source of emissions.

“We have high-level pathways,” Wieland said. “The details still have to be worked out.”

Environmental advocates said they look forward to seeing those details.

“Our major concern is that Massport’s focus is exceedingly narrow here,” said Bradley Campbell, president of the Conservation Law Foundation in Boston. “This is less a plan and more a plan for a plan. Massport could do a lot more to reduce emissions than what’s laid out.”

Chris Marchi, vice president of East Boston group Airport Impact Relief, Inc., urged Massport officials to limit the growth of Logan — and its other airports in Worcester and at the Hanscom Air Force Base — as well as discourage visits by single-occupancy vehicles by raising fees.

If passenger traffic resumes the steady increases that occurred before the pandemic, the proposed emissions cuts could be moot if emissions increase in other ways, he said.

“As much as it is an admirable goal to reach zero emissions, these efforts are more green-washing than they are serious responses,” Marchi said.

At a Massport board meeting on Thursday morning, in which officials explained their plan to reduce emissions, several board members raised concerns that it doesn’t do enough to reduce the authority’s overall pollution.

“As someone who lives almost a stone’s throw from the airport, I’m concerned, as is the community in which I live, about the overall impacts of Massport on the community,” said John Nucci, a former city councilor from East Boston who serves on Massport’s board. “I don’t want to see a situation where people who live around the airport have to wait until Massport has spent $1 billion … before that overall impact gets substantially reduced.”

Wieland responded by noting that the plan remains “aspirational.”

“We have a lot of work left to do,” she said.

Read the full article in The Boston Globe here.