In 2005 10 Northeastern and Mid-Atlantic states banded together to create the Regional Greenhouse Gas Initiative, or RGGI, to reduce carbon emissions.

The Regional Greenhouse Gas Initiative is a form of carbon pricing. It sets an annual cap on the total amount of carbon dioxide emissions allowed for the collection of all large electricity power plants located in the RGGI states, a cap that declines over time.

So that the cap is not breached, only limited authorizations to emit CO2, called allowances, are sold at auction. Each allowance entitles a regulated source to emit one short ton of CO2, and every large power plant has to buy and surrender the number of allowances equal to their emissions.

The revenue from the auctions goes back to the states where the power plants are located, and the majority of it is used to incentivize energy efficiency investments. In Maine this revenue — more than $83 million at last count — is a major source of funding for Efficiency Maine.

Because RGGI is in one of its periodic reviews, it is a good time to take a retrospective look at how this program has stood the test of time. At its inception, proponents expected it to achieve modest reductions at a modest cost, while detractors expected it to be an ineffective emissions-reducer and a job killer to boot.

It turns out they were both wrong. It achieved large reductions, it stimulated the economy, and it was a job creator.

Within RGGI states fuel-switching, improved energy efficiency, and growing renewable energy output have caused emissions to drop by 37 percent since RGGI was launched. During that time, member states have reduced emissions by 16 percent more than other states, seen 3.6 percent more economic growth, and experienced a net increase of more than 30,000 new job-years.

Meanwhile, Maine’s use of RGGI auction proceeds to fund Efficiency Maine has lowered energy costs, which have helped Maine businesses to become more competitive and homeowners to have more affordably comfortable homes.

This evidence is both significant and timely. Studies make it clear that delay in acting on climate change not only significantly raises the cost of taking action, but it also raises the economic damages caused by the resulting additional emissions. Since some of the CO2 will remain in the atmosphere for thousands of years, the window of opportunity for cost-effective action is closing as the carbon levels in the atmosphere grow to threatening levels.

A place to start is the RGGI board of director’s current deliberations about how much the cap should decline in the future. Analysis suggests that a decline of 5 percent per year would be the most cost-effective way to achieve the region’s stated emissions reduction goals. A 5 percent annual reduction, which is one of the specific proposals before the board, would exceed the current required decline rate of 2.5 percent each year, but would be more gradual than the annual emissions reductions actually achieved by RGGI to date.

Next it would be necessary to extend the scope of existing or new carbon-pricing programs, as Canada has just done. The expanded scope would include other sources and greenhouse gases — remember RGGI applies only to CO2 power plant emissions — and other states and regions.

The good news is that recent polls indicate that a majority of Democrats and a majority of Republicans want to take action on climate change.

What about the minority who doesn’t agree with the scientists on climate change, but do have political power?

In situations like this, it is instructive to look at the cost of being wrong. If those who reject climate science are wrong and we don’t take action, the ensuing climate damages would certainly be serious and potentially could be catastrophic.

If, however, the scientists are wrong and we take action earlier than necessary, both experience and forecasts suggest the costs would likely be small and, in any case, well justified by the assurance of lower risk.

Given these choices it should be possible to find common ground among all people who have at least some aversion to risk. I doubt anyone wants to be labeled as the generation who blew the last best chance to save the planet from irreversible, massive climate damages.

Tom Tietenberg, the Mitchell Family Professor of Economics, Emeritus at Colby College and a member of the Sustain Mid-Maine Coalition, has spent more than 30 years helping to craft mutually acceptable, cost-effective, market-based programs to control pollution. Elery Keene also contributed to this piece.