After years of study, drafting and consultations with stakeholders, Sen. Jeff Bingaman on Wednesday introduced a bipartisan bill to establish an economy-wide mandatory cap and trade program to curb emissions of greenhouse gases.

The measure (S 1766), called the Low Carbon Economy Act, joins several other bills to be considered by the Environment and Public Works Committee.

Joining Bingaman, D-N.M., as cosponsors are Sens. Arlen Specter, R-Pa., Tom Harkin, D-Iowa, Daniel Akaka, D-Hawaii, and Alaska Republicans Ted Stevens and Lisa Murkowski.

At an unveiling ceremony, Bingaman, chairman of the Energy and Natural Resources Committee, was joined by labor leaders and power company executives who praised what they said was the bill’s moderate approach.

Bingaman said he hoped climate legislation would reach the Senate floor in the fall, although he acknowledged that getting a measure through the Congress and signed by the president would require heavy lifting.

Noting the bill’s backing by industry and labor unions, Specter said, “I think we have the firepower to get it done.”

President Bush opposes mandatory measures to roll back emissions of greenhouse gases, primarily carbon dioxide, blamed for contributing to global warming, preferring to rely on technological advances and international cooperation.

But Bingaman said the idea of introducing a bill to be an issue in the next election campaign “is not our position.”

He said the bill contained no provisions to pre-empt climate action that states are already taking.

Starting in 2012, the bill’s goal is to reduce greenhouse gas emissions to 2006 levels by 2020 and to 1990 levels by 2030, with a 60 percent reduction in current levels by 2050, contingent on science, technology development and international effort. Other bills have more ambitious targets.

The 130-page bill would regulate petroleum refineries, natural gas processing plants and liquid natural gas facilities, importers of fossil fuels and greenhouse gases other than CO2 and large coal consuming facilities — those that use more than 5,000 tons of coal a year.

It contains a provision that has sparked criticism from some advocates of strong climate action — a “safety valve” for emissions costs that could be used to limit economic uncertainty and price volatility.

Under this mechanism, emitters would make a technology accelerator payment (TAP) — starting at $12 per metric ton of CO2-equivalent in the first year and rising annually at 5 percent above the inflation rate.

TAP money received would go to a new government energy deployment technology fund.

Eileen Claussen, president of the Pew Center on Global Climate Change, said that intervening in the market through a low price cap “could both render the emission levels established in the bill meaningless and undermine investment in the next generation of climate-friendly technologies.”

David Doniger, climate policy director at the Natural Resources Defense Council, said the safety valve meant that the targets for greenhouse gas reductions, already not strong enough, might never be reached.

Dave Hamilton, director of global warming and energy programs at the Sierra Club, said the safety valve level “basically guarantees a safe place for pulverized coal to avoid accepting its carbon costs for longer than it should.”

At the start of the program, most allowances would be given out free to the private sector and the rest auctioned, the funds going to technology development, climate adaptation and assistance for low income families.

The bill aims to promote carbon capture and storage deep underground. Facilities built or retrofitted by 2030 would receive bonus allowances for each ton of CO2 sequestered during the first 10 years of operation.

Five percent of total allowances would be set aside for agricultural sequestration projects.

The bill would fund joint research and development partnerships and technology transfer programs similar to those of the six-nation Asia-Pacific Partnership led by the United States.

Every five years, domestic progress on emissions would be reassessed by Congress and the president in the light of efforts being made by America’s major trade partners.

Sufficient international progress could result in the president recommending changes in the U.S. program aimed at achieving further reductions at least 60 percent below current levels by 2050.

If other countries’ efforts were deemed inadequate, the president would be able to require importers from those countries to purchase allowances to cover the carbon content of imported products.

The bill’s promise of funds for adaptation to climate change would likely help Alaska, where warming temperatures have been melting permafrost and Arctic sea ice, leaving shore towns more vulnerable to Pacific storms.

“This is a rational response,” Murkowski said of the bill. “It isn’t going to sink our economy.”

Bingaman said most of the cost of the program would be covered by the mechanism for auctioning allowances, adding, “We do not expect this to be a major budgetary item.”

“I understand there are some that would like a more aggressive set of targets but what we’re trying to do is to put together legislation that will be passed,” he said.

But NRDC’s Doniger said there was a continuing change in what was seen as politically feasible and the bill’s targets were not strong enough to protect against dangerous climate change.

The Sierra Club’s Dave Hamilton said: “The argument that we have to settle for an inferior product now does not give enough credit to the speed in which things are moving.”

When the Bingaman bill and other climate measures are taken up by the Environment Committee they will face implacable opposition from its top Republican, Sen. James M. Inhofe of Oklahoma.

Reacting to the bill Wednesday, Inhofe, the Senate’s leading climate skeptic, said the “spectacular global failure” of the 1997 Kyoto Protocol “should give any advocates of mandatory CO2 cap-and-trade schemes serious reasons to reconsider their support.”

The bill would “needlessly increase energy costs to already overburdened Americans without any measurable climate benefits,” Inhofe said.

Committee Chairwoman Barbara Boxer, D-Calif., said she welcomed Bingaman’s introduction of the bill.

“I look forward to carefully considering his proposal in the Environment and Public Works Committee, along with the other global warming bills, as we move the legislative process forward,” she said in a statement.

“I am optimistic that working together across party lines, we can pass strong global warming legislation in the Senate this year, and I believe Senator Bingaman’s bill is an important contribution to that effort.”