Leadership in the effort to reduce carbon emissions that cause health problems and fuel global warming won't be coming from Washington, D.C., for the foreseeable future. Leadership will have to come from the states, and nine Northeastern states, including Massachusetts, made a bold step in the right direction this past week.

The states comprising the Regional Greenhouse Gas Initiative (RGGI) announced an aggressive market-based plan to cut power plant emissions by 30 percent. The product of a year's worth of negotiations, the plan builds off the proven success of past emission-reduction efforts initiated by the RGGI. Each state must implement the plan individually, but with representatives from all nine RGGI states approving the plan, implementation is not anticipated to become a problem.

The RGGI, begun in 2005, was the first cap-and-trade program in the U.S. to limit carbon dioxide (CO2) emissions from power plants. Power plants have been allowed to purchase pollution permits at auctions several times a year. The caps on emissions have been steadily lowered, making them more expensive and giving companies incentives to use clean energy. Proceeds from the auctions are used to fund energy efficiency programs — about $440 million worth in the state since 2008.

The agreement announced last week steps up the pace of CO2 reductions by mandating cuts in emissions by 30 percent between 2020 and 2030. In Massachusetts, this would result in a dramatic reduction of 65 percent in the two decades from 2008. The agreement also introduces new tools to help states make those reductions, most notably by allowing them to further reduce emissions caps by 10 percent a year should the price for pollution permits falls below anticipated levels.

While a number of environmental groups had advocated for deeper emissions reductions over the past year, all expressed support of the agreement, with Peter Shattuck, director of the Acadia Center, a Boston-based advocacy group, telling The Boston Globe "This is what climate leadership looks like." Significantly, the New England Power Generators Association (NEPGA), which has opposed emissions reduction mandates for not considering the burden on its members, praised the new agreement, as it has the RGGI in general. "Market-based programs provide the most efficient, competitive, and lowest-risk way to address climate change," said NEPGA President Dan Dolan in The Globe.

It is not anticipated that the emissions-reduction plan will affect consumer prices because the coal and oil plants that were the largest polluters have closed. Massachusetts is home to about 150 of New England's 350 power plants, and according to Mr. Dolan, the region's plants have reduced CO2 emissions by 40 percent since 1990.

The RGGI is indeed an example of climate leadership in action. While Massachusetts was not one of the seven states that were original members, the state joined in early 2007 in one of the first actions of newly elected Governor Deval Patrick. The initiative now consists of all six New England states along with New York, Delaware and Maryland.

The Acadia Club has found that RGGI states have reduced their emissions by 16 percent more than other states while seeing economic growth of 3.6 percent more than those states. Energy prices fell by an average of 3.4 percent while rising by an average of 7.2 percent in non-RGGI states. Those numbers are backed by the Sierra Club and other environmental organizations. The Cambridge, Ma.-based consulting group Abt Associates said in The Globe that it estimates the the RGGI has resulted in the saving of as many as 800 lives, reduced asthma attacks by bout 8,000 and saved as much as $6 billion in health care costs.

The state will not be fully addressing the carbon pollution issue, however, until it finds ways to fix the transportation sector, which accords for an estimated 40 percent of such emissions. Earlier in the month, following a Supreme Judicial Court ruling that the state was not on pace to meet the requirements of the state Global Warming Solutions Act of 2008, Massachusetts Energy and Environmental Affairs Secretary Matthew Beacon acknowledged that the state will not meet the Act's requirements without addressing transportation. While praising the RGGI agreement, the Union of Concerned Scientists urged the member states to "build upon the success of RGGI and set their sights on a regional solution to transportation sector emissions."

That would be a worthy next step for RGGI. More immediately, Massachusetts must quickly issue regulations to implement the new RGGI agreement. Then, the state and its eight fellow states can celebrate the completion of a pact that is in essence an unofficial response to President Trump's decision to withdraw the U.S. from the Paris Climate Agreement, an act which has unfortunate ramifications both real and symbolic. On the very real problems of climate change and environmental degradation, the states will have to lead.