New England’s market-based approach to reducing carbon dioxide emissions shows that states can fight climate change while still improving their economies, the region’s top environmental officials said Wednesday.

Curt Spalding, Environmental Protection Agency administrator for New England, suggested that Maine and most other northeastern states had already compiled a “toolbox of tools” to meet the federal agency’s proposed rules for slashing carbon dioxide emissions from power plants nationwide. The goal now, Spalding said, is to put in place a national framework flexible enough to work in all states.

“What this rule tries to do … is to take advantage of the building blocks that have been put in place in places like New England,” Spalding told several dozen people in a University of Southern Maine lecture hall.

Spalding spoke about the EPA’s proposed carbon standards for power plants during an unofficial “listening session” in Portland organized by the Natural Resources Council of Maine, the Island Institute and the Voter Education Brigade. “The first goal is to get the framework in place so that the kinds of continuous improvement experience we’ve had here in New England can happen everywhere,” Spalding said.

Spalding pointed out that New England’s gross domestic product has increased 22 percent since 1999 while carbon emissions have declined 20 percent.

In June, the EPA unveiled proposed rules to reduce carbon dioxide emissions from power plants by 30 percent by 2030. The rules, which use 2005 emission levels as a starting point, are part of the Obama administration’s effort to reduce greenhouse gases linked to climate change. Each state was given a different target, with Maine expected to reduce emissions by 13.5 percent by 2030.

The EPA is still discussing technical details of how New England’s existing carbon emission reduction system – the Regional Greenhouse Gas Initiative – will mesh with the proposed rules, under which states are supposed to start showing carbon dioxide reductions by 2020. However, Spalding said the proposed rules were designed to be flexible and should enhance existing programs such as the New England initiative.

Spalding was in Maine days after a dozen other states filed a lawsuit challenging the EPA proposal and roughly one week after several thousand people attended public hearings held in four cities around the country. Speakers at those public hearings were deeply divided with the strongest opposition coming from coal-mining states and areas where coal is the dominant source of fuel for power plants.

The crowd at Portland’s unofficial “listening session” was decidedly friendly to the proposed rules. Speakers warned that a warming climate was already affecting Maine’s commercial fisheries and could have dramatic impacts on lobster, clams and other shellfish as higher carbon levels lead to more acidic oceans.

“If we do not cut carbon emissions now, particularly from power plants, it becomes much more difficult if not impossible to protect ourselves from the worst ravages of climate change,” said Tom Tietenberg, professor emeritus of economics at Colby College who has researched climate policies. “The window of opportunity is closing. The time to act is now.”

Dr. Tony Owens, an emergency physician at Maine Medical Center, said he admitted three people Tuesday who attributed their breathing problems to poorer air quality. “I see the effects every day,” Owens said.

The EPA’s carbon reduction plans have not been controversial in Maine, largely because the six major power plants in the state have been operating under a carbon-reduction plan for five years. In addition, the state has no coal-fired power plants.

The Regional Greenhouse Gas Initiative is a nine-state program that imposes a cap on carbon dioxide emissions from fossil fuel-burning power plants and then requires those facilities to buy credits for each ton they release. Credits are traded on a carbon market like other commodities, generating revenue for energy conservation or home weatherization in Maine while giving regulated facilities a financial incentive to reduce emissions below their caps.

Emissions from power plants in the nine states have fallen 40 percent, although market trends toward cleaner-burning natural gas and away from coal and oil are also major factors.

Spalding said it was too early to tell whether Maine and the other eight participating states would be required to reduce emissions further under the EPA proposal. The EPA and the states must reconcile the different methods that the two systems use to calculate emissions.

“The thought around the rule is that these kinds of market-based approaches, under RGGI or other types around the country, are good things and we hope this rule will encourage their success in time,” Spalding said after the meeting.

Marc Cone, director of the air quality program at the Maine Department of Environmental Protection, said the states and the EPA are “working our way through” what he described as one of the most complicated sets of air regulations ever proposed. Cone said his department wants more data on how the EPA calculated its baseline emissions levels and goals to ensure that the state is given credit for its high reliance on renewable energy and successful carbon reduction to date.

Cone said the DEP is “certainly hopeful” that Maine will get credit for its progress under RGGI. “But sometimes the details need to be fleshed out . . . and some of the details are still fuzzy,” Cone said.

The EPA is accepting public comment on the carbon dioxide reduction proposal through Oct. 16. To submit a comment, to go http://www2.epa.gov/carbon-pollution-standards