While Gov. Charlie Baker portrayed Massachusetts as “a national leader” on climate during his State of the Commonwealth address Tuesday, Baker and the Legislature remain at odds over how the state should reach its emissions-reduction goals.

Baker vetoed a climate bill this month, but lawmakers appear unconvinced by the rebuke. The House and Senate plan to vote Thursday on the unchanged bill, which maps a plan for Massachusetts to reach net-zero carbon emissions by 2050.

Baker declared his support for that goal last January. But, in a letter detailing his veto, he claimed that the Legislature’s more aggressive interim reduction goals were too costly and that a new opt-in building code could hurt housing production.

Not swayed, lawmakers and climate advocates blasted the veto for delaying climate action they see as urgent. Some have argued that fossil fuel-aligned lobbyists played an outsize role in derailing the legislation.

While the Legislature says its approach brings the ambition necessary to address the severity of climate change, Baker’s camp cites data and research as the basis of its own strategy.

Debate over costs

Baker, in his veto letter, said that reaching the Legislature’s 50 percent interim reduction goal would cost $6 billion more than his administration’s 45 percent goal — a claim that some lawmakers and advocates have disputed.

Either target would be the most ambitious in the nation, said Secretary of Energy and Environmental Affairs Kathleen Theoharides, noting that California and New York set interim reductions goals of 40 percent by 2030.

“You don’t necessarily want to make the changes too fast, because the costs for Massachusetts residents would be much higher,” Theoharides said, claiming that the Legislature’s goal was not based in data analysis. “We believe that ambition should be backed up with data and recognizing the costs that residents across the state will have to bear.”

Lawmakers and climate advocates, though, aren’t budging.

“The bottom line is that we need to get off of fossil fuels and reduce our carbon emissions as quickly as possible,” said Ben Hellerstein, executive director of Environment Massachusetts. “What the science tells us is, the more we can do and the sooner we can do it, the better.”

“We can’t keep doing the same-old, same-old,” said state Rep. William “Smitty” Pignatelli, D-Lenox. “Lofty goals give us something to shoot for.”

Some lawmakers questioned why the administration had not revealed its calculations when negotiations were ongoing. The Baker administration first publicized the 45 percent goal Dec. 30, when it released its 2030 clean energy plan and 2050 decarbonization road map.

The more aggressive goal would require an extra 400,000 electric vehicles, a more stringent low-carbon fuel standard and an additional 2,000 megawatts of clean energy, according to the Baker calculations. That means the state would need to incentivize more people to ditch gas-powered cars or gas heating than might otherwise be ready to, Theoharides said.

“What [the 50 percent goal] means is starting to encourage people not just to make the switch to an electric vehicle when they need a new car, but to pay people to buy new electric vehicles before they otherwise may buy a car,” Theoharides said. “It takes a bit richer of an incentive.”

Some pushed back on the grounds that the Baker administration did not account for the possibility of federal action that could take some financial burden away from states. The quicker phasing out of fossil fuel investments, Hellerstein argued, should be seen as an advantage of the more aggressive approach.

“We’re going to waste less money on fossil fuel infrastructure that we know is going to be obsolete in just a couple of decades,” he said.

Housing concerns

Baker also cited concerns raised by trade associations. He quoted Rick Sullivan, CEO of the Western Massachusetts Economic Development Council and a former energy secretary under Gov. Deval Patrick, who claimed that a proposed new building code would “likely result in construction slowing or outright stopping in many localities.”

State Sen. Adam Hinds, D-Pittsfield, said tackling climate change requires the Legislature to “go all in,” and that if doing so negatively impacts housing construction, further legislation can remedy those impacts.

“To compromise our progress on confronting climate change in any way is unacceptable at this time,” Hinds said, adding that the housing construction argument “rang hollow” to many senators.

Several real estate-aligned groups have ties to fossil fuel-interested utility companies. The Western Massachusetts Economic Development Council, for instance, is a member of the Massachusetts Coalition for Sustainable Energy, which lobbied against the bill in June.

“It sounds like a climate-friendly name, but in essence it’s a front group that’s pushing for more gas pipelines and is funded by the main utilities in the state and by trade associations,” said Itai Vardi, a research and communications specialist at the Energy and Policy Institute.

New vote

If the House and Senate pass the bill again Thursday, as expected, Baker would have the ability to return the bill to the Legislature with proposed amendments, which the Legislature then could accept or reject.

Pignatelli said the process could wrap up in “three to four weeks.”

“In fairness to the governor, he got the bill late and we limited his ability to send it back amended,” Pignatelli said. “I think we’ll hopefully send back the same bill, he’ll amend a couple of portions, [and] we can debate it, further amend it and ship it back to him in very short order.”

Theoharides expressed hope that the Legislature could integrate Baker’s feedback before passing the bill again.

“Now they have the information and they’ve seen the analysis, and we hope that will be part of the consideration,” she said.

Hellerstein said he would like to see the bill done by Feb. 19, the deadline for lawmakers to file bills, so that work can move to other legislation on the state’s transition to renewable energy.

“Solving climate change is pretty simple: We need to stop using fossil fuels across all sectors of our lives as quickly as we can,” Hellerstein said. “That’s not to say it’s going to be easy or that there are no complications, but we know that’s what we need to do.”

Danny Jin, a Report for America corps member, is The Eagle’s Statehouse news reporter. He can be reached at djin@berkshireeagle.com, @djinreports on Twitter and 413-496-6221.

Statehouse Reporter

Danny Jin is the Eagle's Statehouse reporter. A graduate of Williams College, he previously interned at the Eagle and The Christian Science Monitor. Danny can be reached at djin@berkshireeagle.com or on Twitter at @djinreports.