THE SENATE’S POINT person on climate change legislation said he doesn’t know where Gov. Charlie Baker came up with his estimate that the Legislature’s target for emissions reductions in 2030 would cost state residents an extra $6 billion.

 “Boy, would I like to know,” said Sen. Michael Barrett of Lexington. “I have never – and I am familiar with all of the written documents the administration has released on this topic – I had never seen that $6 billion figure until [Thursday]. I wonder if the governor had ever seen the $6 billion figure until [Thursday].”

 In his letter vetoing the Legislature’s climate change bill, Baker said the difference between a 45 percent reduction in emissions by 2030 compared to 1990 levels versus a 50 percent reduction was $6 billion in extra costs incurred by Massachusetts residents. “Unfortunately, this higher cost does not materially increase the Commonwealth’s ability to achieve its long-term climate goals,” the letter said.

 A spokesman for the Baker administration wasn’t able to produce the analysis yielding the $6 billion figure on Friday but promised more information this week.

 Barrett, appearing on The Codcast with Bradley Campbell, the president of the Conservation Law Foundation, said he has asked repeatedly for information on the $6 billion figure and never received it. 

 “I can’t wait to see the economic study that buttresses that claim because it will be unlike any economic study I’ve ever read,” he said. “These figures to some extent are arbitrary. Neither figure [45 percent or 50 percent] is supported by modeling. Both are judgment calls.” 

 Campbell said the governor’s reputation for addressing climate change will take a hit because of his veto of the Legislature’s bill. He said trying to estimate the future costs of addressing climate change is difficult and estimates are typically way too high. He said Baker’s veto wastes valuable time and suggests the governor still believes addressing climate change comes at the expense of the economy.

 As for the governor’s veto letter, Campbell said he was not convinced. “It really was a cobbled-together collection of politically tinged arguments rather than substantive objections that the Legislature could have addressed,” he said. “In some cases, they were objections the Legislature did address.”

Barrett felt similarly. “I assume the governor didn’t write it himself, that it was a staff workup,” he said. “I could not extract from it a coherent, well-constructed case against anything currently in the Senate bill.”

 The senator said no studies, data, or statistics were cited for why the Legislature’s bill would have hindered the development of new housing, one of the governor’s claims.  Barrett also said the stretch energy code developers objected to in the Legislature’s bill —and which Baker cited in his veto letter — was something the Baker administration included in its own climate roadmap.

The climate change bill reached Baker’s desk on the next-to-last day of the legislative session, which meant the governor was forced to either sign it or veto it. But Barrett said the administration was given plenty of opportunity to raise concerns about what was in the bill over the past year, but said little or nothing.

“It is so exasperating to have the governor wax indignant about not having a seat at the table when I had given his people a seat at the table and, due to their own choices, the seat had remained empty,” he said. 

Barrett said he suspects the rigid requirements of the bill – setting five-year targets for emissions reductions with specific goals in industry sectors – prompted the veto because those requirements require action now and not in the distant future.

“We are not due for the next check-in on whether we’re reducing emissions as we must until the year 2030,” Barrett said. “That is upsetting a lot of people, so we are trying to bring the timelines closer to the current era, the current Legislature, and – quite candidly, and I think this has been a point of contention with the Baker people – the current governor. We want Massachusetts having to meet five-year limits or goals.”

Legislative leaders say they plan to bring the bill the governor vetoed to another vote in both branches and send it back to the governor for a second time. Barrett said what will emerge during the legislative process is unclear.

“There are no guarantees in do-overs,” Barrett said. “While I’m guardedly optimistic, the truth is this could go south in some way that we can’t anticipate. The governor has put us in peril here. The speaker and the Senate president are determined to rescue us. Let’s hope this goes well.”