FAIRFIELD — Dan Esty sees the environmental regulatory rollbacks taking place on the federal level and it worries him. But he also takes a look at who is stepping up in the wake of the federal pullback and feels optimistic.

Esty, the former commissioner of the state Department of Energy and Environmental Protection, now a law professor and director of Yale University’s Center for Environmental Law and Policy, spoke on the “Future of Environmental Protection in the Trump Era” Wednesday as part of the Aspetuck Land Trust’s Haskin Lecture Series.

“What is going on at the EPA has to worry anyone,” Esty said, noting that not only are regulations being rolled back, but deep budget cuts are also being made to the U.S. Environmental Protection Agency. Those cuts, he said, decrease the flow of money to the states, hampering their ability to protect the environment, and the public.

“It puts us in a very bad place,” he said.

Don Hyman, recently elected president of the land trust, agreed.

“Many of us tonight are concerned about the local, national and world stability,” Hyman said, and Trump-era action on the environment. To protect the environment, he said, “We can stand on the shoulders of the Aspetuck Land Trust members who came before us.”

One reads the news stories, Hyman said, and you ask, “Are we overreacting?”

Withdrawing from the Paris climate accord — something Esty said can’t actually begin to happen until 2019 — may anger many, but he said while the federal government wants to back away, others are taking its place.

“There are governors and mayors, and corporate leaders, and university presidents and NGO leaders who are stepping up,” Esty said. While the federal government “all but failed to show up” at this week’s UN Climate Change conference in Bonn, Germany, he said, “Gov. (Jerry) Brown of California, and dozens of mayors and many directors of companies are there in their place.”

Unlike decades ago, when environmental protection efforts began and problems were obvious, Esty said today’s environmental challenges require new approaches.

Rivers in Connecticut are much cleaner, he said, and the air clearer. “Now, many of the problems are more difficult to see, and touch, and require new strategies to deliver new outcomes,” Esty said.

Esty oversaw the revamping of Connecticut’s environmental agency to include energy as part of its mission. “It represents one of the things we’ve learned — that the environment and energy need to be integrated,” he said. He expressed his disappointment that the state’s Green Bank is now drastically reduced because of the state budget.

The Green Bank was a way to use limited state funds to leverage private capital to fund clean-energy projects. It enabled seven or eight times as many energy-efficient projects than before the the Green Bank began in 2010, according to Esty.

One thing that is key to finding innovative ways to protect the environment, Esty said, is bipartisanship.

“I do not think you can deliver transformative change on a one-party basis,” he said. The Green Bank, Esty said, took a lot of late nights, “but in the end, we pulled together.” The bill establishing the bank passed the Senate unanimously, and there were only five “no” votes in the House, he said.

“It takes hard work; it takes compromise,” Esty said. “We can move forward, but it’s not going to be easy.”