Tuesday was a terrible day for carbon in Massachusetts.

On the same day, House and Senate leaders and Gov. Charlie Baker all suddenly declared their support for net-zero carbon emissions by 2050, a policy that climate change activists have been pushing for years.

The announcements, which came one after another and under very different circumstances, all but guarantee that the long-term target sought will be adopted this year, altering and accelerating the trajectory of the state's shift away from fossil fuels and toward renewables.

For 12 years, Massachusetts has had a law on its books requiring the state to reduce its emissions to 80 percent below 1990 levels by 2050. The new net-zero target would set a more ambitious 30-year goal, creating a more welcoming environment for clean power and making Massachusetts a less friendly place for carbon. The cost implications, for consumers and businesses, are not fully knowable at this point, just as the impacts of climate change are not totally certain.

For starters, let's do a reality check. Massachusetts emissions in 2017 were down 22.4 percent from 1990 levels, compared to 21.7 percent in 2016 and 19.7 percent in 2015. State law requires emissions to be 25 percent lower by 2020 - the data on emissions lags so the state won't know how it measures up to the 2020 mandate for a while.

Carbon Pricing Signal

So reaching the net-zero target in 30 years, essentially by decarbonizing the state economy? That's going to be quite the journey.

Dan Dolan, president of the New England Power Generators Association, told the News Service lawmakers should pass a carbon pricing bill if they are serious about driving "deep decarbonization" in the transportation, heating and electricity sectors, essential elements for a net-zero environment.

Sending a carbon pricing signal, Dolan said, is necessary to drive investments in the market.

"From our perspective the best, most transparent way to do that is put a meaningful price on carbon emissions," he said. "My hope is that the governor's call last night can help spur that conversation that has been frankly languishing in the Legislature for several years now."

At the unveiling of his budget bill Wednesday, Baker said advancing the hydropower and offshore wind energy projects now in the works would go a long way toward helping the state meet its goal. A full plan to meet the goal, he said, will be included in a clean energy plan his administration plans to release later this year.

Baker, Senate President Karen Spilka and House Speaker Robert DeLeo won't be part of the Beacon Hill scene in 2050, but the electeds who are in office that year may look back on Tuesday, Jan. 21, 2020 as the day things really began to change in Massachusetts.

Here's how things went down on Tuesday:

— At 1:11 p.m., Senate President Spilka posts an unusual 30-second Twitter video in which she and Senate Energy Committee Chairman Michael Barrett, standing in the Senate chamber lobby, announce that the long-awaited Senate clean energy bill will be released on Thursday. It is not a big surprise, since Senate leaders last year said they'd have a bill ready to debate in January.

Spilka and Barrett do not disclose any details about the bill, but Sen. Marc Pacheco of Taunton, who is hosting a Senate Global Warming Committee hearing, tells the News Service a short time later that he expects the bill to propose net-zero carbon emissions by 2050.

"We know that the world hasn't acted as quickly as we should be and we haven't acted as quickly as we should be at the state level," Pacheco says. "If we're going to do what (the Intergovernmental Panel on Climate Change) and other science tells us, we have to have net zero by 2050."

— Six hours after Spilka's Tweet, Gov. Charlie Baker delivers his State of the Commonwealth address in the House chamber and during his remarks declares: "Yesterday's solutions and yesterday's plans are no longer sufficient. We must continue to take bold action to reduce our greenhouse gas emissions. Tonight, I'm committing the Commonwealth to achieving an ambitious climate goal: net-zero greenhouse gas emissions by 2050." Legislators rise and applaud the remark.

Did Senate leaders try to get out in front of Baker's declaration? Or did Baker piggyback on the Senate? That's a matter for speculation and if anyone has any evidence either way please be in touch.

— After the governor's speech, reporters catch up with Spilka and DeLeo outside the House chamber.

Spilka is asked whether a net-zero goal by 2050 is doable.

"I am sorry if you haven't seen there was a news article today," she says. "The Senate is coming out with a climate bill on Thursday and it will contain a net-zero emissions - greenhouse gas - by 2050. So I'm thrilled that the governor is joining us with that."

Immediately after Spilka finishes her answer about net-zero by 2050 being doable, DeLeo announces his support and the support of the full House, even though the measure appears far from being ready for House consideration.

"I'm also pleased to state the same thing," DeLeo says, speaking after Spilka. "I was pleased to see that the governor had mentioned that today and that is something also that the House will be supporting as well." DeLeo added, "I would very much hope we get that done in this session."

— Statements pour in Tuesday evening from environmental and clean energy groups hailing the updated goal and asserting that it will put Massachusetts back on the path to leadership in the renewable energy world.

The Coalition for Community Solar Access says the target will require "bold action," resurfacing a projection that hitting the 80 percent reduction by 2050 target in New England would require a tenfold annual increase in solar capacity "to decarbonize our economy in the face of growing electricity demand."

"Climate change is affecting our health, our economy, and our way of life," the Environmental League of Massachusetts says. "This commitment is the kind of action we need from our elected officials to protect ourselves from the worst impacts of the climate crisis."

Conservation Law Foundation President Brad Campbell: "Governor Baker's crucial directive puts Massachusetts in the vanguard of states and nations combatting climate change and embracing a clean energy future. We look forward to working with the administration on the bold steps that need to follow."

Paul Craney of the Massachusetts Fiscal Alliance offers a different take, saying the net-zero goal "sounds good" but the state could focus on other pressing issues like the degradation of the Merrimack River, problems in the recycling sector, and solid waste disposal issues.

"These are very big ideas that are pretty unrealistic," Craney says, referring to the net-zero goal. He predicts large expenses associated with shifting toward net-zero emission homes and speculated about electric airplanes and boats.

Craney says Massachusetts also risks being an outlier and says it "makes more sense" for the nation to pursue such a target rather than one state. "Then you're able to move the market with you," he says. "Massaschusetts doing something this radical is not going to move the market."

So, what's next?

Look for the net-zero language to be featured in a bill that Senate leaders plan to unveil Thursday and which will likely clear that branch next week. When and how the 2050 language emerges for a House vote remains unclear, with just over six months remaining for formal legislative sessions.

The long-term, net-zero goal would alter market dynamics in Massachusetts, putting greater pressure on the state and the private sector to advance a clean power agenda more quickly. That would means more pressure to get offshore wind energy projects started, to deliver hydropower to Massachusetts from Canada, and to grow renewable energy sectors, like solar. It would also enhance the importance, from an emissions standpoint, of cutting carbon in the transportation sector, a focus of a developing, multi-state initiative that's likely to cause gas price increases while cycling new money into clean energy initiatives.

Spilka on Tuesday night declared her support for the Transportation Climate Initiative, an idea that has not caught on in northern New England.

"We support TCI and recognize that this is an enormous undertaking and that maybe not every neighboring state or other eastern coast state will join in," said Spilka. "I hope they do. The more states that do the more benefit we will have with greenhouse gas and emissions reductions but even if a few, particularly the smaller states, don't join in, I think they will end up regreting it. I hope that it does come to fruition."

A Spilka aide said "several" senators have expressed support for TCI, explaining why Spilka used the word "we" to describe Senate support for TCI.

DeLeo said Wednesday he likes TCI "as a concept" but needs to see which states are willing to be a part of it.

"We need to see some more states, especially our New England states, that are going to be part of it," DeLeo said. "Right now, what I have read or heard or whatever, I have not seen any other New England states, or any states that are joining with us. That doesn't mean that they won't, and if they do then that's something I think we can take a look at."