Environmental Protection Agency Administrator Gina McCarthy speaks at Harvard Law School in Cambridge, Mass., on Tuesday. (Steven Senne/ASSOCIATED PRESS)

The new head of the Environmental Protection Agency told an audience at Harvard Law School on Tuesday that cutting carbon pollution will “feed the economic agenda of this country” and vowed to work with industry leaders on shaping policies aimed at curbing global warming.

“Climate change will not be resolved overnight,” EPA Administrator Gina McCarthy told the 310-member audience. “But it will be engaged over the next three years. That I can promise you.”

McCarthy made a full-throated defense of her agency’s right to address greenhouse-gas emissions and other pollutants, saying that air-quality regulations and environmental cleanup efforts have already produced economic benefits in the United States.

“Can we stop talking about environmental regulations killing jobs, please?” she asked, prompting loud applause. “We need to embrace cutting-edge technology as a way to spark business innovation.”

She also made a joke of her strong Boston accent by repeating, “And I said, ‘spaahrk.’ ” McCarthy also joked about the challenge she faced in getting her post, calling her confirmation “the honor of a lifetime.”

“That’s a very good thing, because I swear it took two lifetimes to get confirmed,” she said.

The speech represented a homecoming for McCarthy, a Boston area native, who was introduced by her  27-year-old daughter, Maggie McCarey, a program coordinator at the Massachusetts Department of Energy Resources.

McCarthy, a veteran of Republican administrations in Massachusetts and Connecticut, has spent much of the past four years at the EPA shepherding through air regulations, which have come under attack from business groups for helping shut down power plants. Her nomination to succeed former EPA administrator Lisa P. Jackson dragged on for more than four months as several GOP senators used the pick as a way to highlight their problems with President Obama’s environmental agenda.

In her Tuesday speech, McCarthy pointed to the EPA’s history of improving the environment in places such as Lowell, Mass., where she watched the river run blue, yellow and other colors depending on what dyes the textile mills dumped in the water.

She said climate change was now the top priority for the agency, which plans to model its efforts on the administration’s earlier agreement with the auto industry on stricter fuel efficiency standards for cars and light trucks.

“EPA cannot dictate solutions,” McCarthy said. “We have to engage.”

McCarthy has already been meeting with utility executives and coal industry officials, some of whom fear that the administration’s plan to limit carbon dioxide emissions from existing plants will close many plants.

McCarthy also said the agency would continue to focus on water quality and environmental justice, a hallmark of her predecessor, which refers to the problems facing poorer communities that bear the brunt of pollution and other environmental risks.

Hal Quinn, president and chief executive of the National Mining Association, said that McCarthy was “keenly interested” in the group’s technical assessments of the impact of EPA rules during a meeting earlier this year.

But Quinn said he remains worried that the agency will press for unrealistic carbon standards. He said a 2011 rule on mercury and air toxins had forced utilities to retire at least 40,000 megawatts of coal-fired electricity.

“The investments that have been made in utilities could be jeopardized or stranded because of the rules on greenhouse-gas emissions,” Quinn said.

In an interview Tuesday, McCarthy said the utility-closing announcements came far in advance of any EPA rule requirements. “It’s hard for me to think our rule is the driving factor behind these closures,” she said. “This is about the abundance of low-cost natural gas. It’s about how utilities are making decisions, company-wide, about how to invest in the future the way they see it right now.”

On the controversial Keystone XL pipeline, McCarthy said in the interview that the EPA would not weigh in on the issue until the State Department releases a final environmental assessment of the project. While she did not indicate what position the agency would take, McCarthy noted that Obama “sent a very strong signal” during his June climate speech “that climate’s impact would be taken into consideration in this decision, and in others.”

During the question-and-answer portion of Tuesday’s speech, McCarthy jokingly began to cut off the session once a Sierra Club member posed a question about the Keystone pipeline.

But she vowed to “continue to work with the administration as difficult decisions are made” and compared charting national environmental policy to reconciling interests in a noisy family.

“It’s not supposed to be easy. It’s supposed to be hard. It’s supposed to be all the different voices coming together screaming at the top of their lungs like three children,” she said, adding that she would work to allow “all those voices to be heard and to listen to them. And it’s my obligation to keep peace in the family, whether it’s my EPA one or my little one.”