IN A NEW SURGE of opposition, advocates are calling directly on Gov. Maura Healey to stop the expansion of the publicly owned airfield in Bedford that holds the most private jets in New England.

The Massachusetts Port Authority, a quasi-public agency, has proposed adding 27 hangars at Lawrence G. Hanscom Field in Bedford, raising concerns about increased carbon emissions from private jets that critics say only serve the wealthy.

According to a coalition of local and environmental groups who call themselves Stop Private Jet Expansion at Hanscom or Anywhere, the airfield development would add nearly 500,000 square feet of hangar space for the 27 private jet hangars on 49 acres of land. The changes could add a potential of 81 private jets to the airfield, with two to three planes per hangar, which would triple Hanscom’s private jet capacity, the coalition said.

The expansion plan is undergoing a Massachusetts Environmental Policy Act (MEPA) Office review, which requires Massport to file an environmental impact report that will include the agency’s estimates on public health impact and fossil fuel emissions.

report released Monday from the Institute for Policy Studies, a DC-based think tank, found private jet flights from Hanscom Field accounted for an estimated 106,676 tons of carbon emissions over an 18-month period.

Private jets pollute 10 to 20 times more per passenger than their commercial counterparts, report co-author Chuck Collins told the News Service, and planes from Hanscom are largely bound for places like Nantucket, Martha’s Vineyard, Aspen, the Hamptons, Palm Beach, the Bahamas and Turks and Caicos.

Over the 18 month period studied, 20 private jets accounted for 10 percent of flight activity — a total of 3,240 flights emitting an estimated 14,930 metric tons of carbon.

An average Massachusetts resident contributes eight tons of emissions every year, Collins said.

The Institute for Policy Studies report estimates 41 percent of the private jet flights leaving Hanscom take less than an hour to get to their destination. Because jets burn the most fuel on takeoff, it says, short flights are even less energy efficient than longer flights, and much less efficient than alternative transportation options.

“You’ve got some of the most wealthy fliers in their private jets going in and out of Hanscom … going to places like Nantucket where there are other options to drive and take the ferry, or to New York, where they could take the train. There are other transportation alternatives that are miniscule in their emissions comparatively,” Collins said.

Coalition advocates led by Sen. Michael Barrett, who co-chairs the committee reviews climate bills, held a rally against the airfield expansion on the State House steps Monday. The activists then took their plea to Healey’s office, delivering a petition with over 10,000 signatures.

“We are here today supporting our governor who has promised to be our climate protection champion. We are here in solidarity with her administration, because we need her to show us that protecting the climate was not just a promise for her campaign, but an essential principle that will guide every decision she makes in office,” said Lincoln resident Alex Chatfield.

Over 100 protesters convened outside Healey’s office and delivered the petition to the governor’s staff Monday afternoon.

Executive Office of Energy and Environmental Affairs spokesperson Maria Hardiman responded with a statement to a question to the administration about the advocates’ demand that the governor oppose the expansion.

“The Healey-Driscoll Administration is committed to reducing emissions and protecting the health of Massachusetts residents. The MEPA Office will carefully review the environmental impacts of this proposal and is continuing to engage with communities impacted by airport emissions,” Hardiman said.

In a speech from the State House steps, Barrett directed some of his comments at the rally directly to Massport’s board of directors.

“Now [Massport’s] board of directors is the big decider here, so today we direct them a plea — it’s not too late to do the right thing. If you don’t, you put Massport at risk of becoming a pariah. A poster child for reckless disregard of the public interest by a governmental body,” Barrett, who lives in Lexington near the airfield, said. “If 27 — or 18 — or just a dozen — of these hangars get built, the agency will never come back from the reputational damage. Going ahead would be an unforced error, one of the greatest ones in modern Massachusetts public policy.”

Collins, the co-author of the Institute for Policy Studies report, also spoke to the crowd.

“Should we triple the private jet capacity at Hanscom so that a bunch of people in the top .001 percent can jet to Nantucket and Arbua?” Collins said at the rally. “And Massport — in the face of a summer of climate disaster, aren’t there any other infrastructure projects right now?

Massport spokesperson Jennifer Mehigan wrote in an email that the proposed Hanscom expansion is a response to existing demand at the airfield.

“Hanscom plays a critical role in the regional aviation system as an FAA-designated general aviation reliever for Logan Airport,” Mehigan wrote.

She added that one of Massport’s primary missions is to support Massachusetts’ businesses to compete in the global economy.

Mehigan noted the project is still in the MEPA review, and there will be public process before anything is finalized. She also pointed to project features designed to make the expansion more sustainable, “including a LEED Gold, or better, certified design, a high target for energy efficiency and net zero energy, photovoltaic solar roof panel systems, rooftop and pavement materials that reduce urban heat, and, resiliency measures to protect the site and adjacent parcels from potential future flooding.”

Advocates at the rally warned that expanding the airfield would undermine the state’s climate efforts, offsetting investments that have been made into renewable energy and cutting emissions.

Massport committed in 2022 to reduce its carbon emissions to net-zero across all its facilities by 2031, though this target applies to infrastructure under Massport’s control, and the agency does not account for aviation emissions in that net-zero goal, Collins said.

The agency last week convened with MIT researchers and aviation companies Boeing, Delta, Pratt & Whitney and World Energy to “discuss paths towards achieving a future where aviation can connect the world with drastically reduced environmental impacts.”

“The proposed Hanscom project does not go against Massport’s commitment to our neighboring communities and the environment,” Mehigan said.

Local advocates also came out for Monday’s rally, including 5th grade Lexington student Kalea Foo.

Foo said she is worried about climate change already affecting Massachusetts.

“At the start of the school year we couldn’t go outside for recess because it was so hot, way hotter than what used to be normal. But some schools didn’t have air conditioning, so it was scorching inside their classrooms, and some schools even had to close,” Foo said. “It’s not safe outside and it’s not safe inside. What do you want us to do? For our generation, this is way more scary.”