On a chilly winter morning, Back Bay resident Jackie Royce stood just outside Copley Square, describing the route of a new natural gas pipeline extension that National Grid plans to build through her neighborhood and the South End.

"It’s going to come up Berkeley Street," Royce said, "and then it’s going to turn here and go down Huntington."

To say Royce isn't a fan of the project would be an understatement.

"Delay it," Royce said when asked what she hopes will happen to the pipeline. "Delay the approval of opening up the street, and delay it getting started."

Royce is active in the Neighborhood Association of the Back Bay, a civic group which has, over the years, developed a bit of a reputation for NIMBY-ism (Not In My Back Yard). But as she tells it, her opposition isn't parochial at all. Instead, it's about principle and policy.

"This was not a good idea, to commit us to fossil fuel infrastructure when the city has climate goals, and obviously things are happening around here," Royce said.

That's a reference to the intense winter storm that hit Boston earlier this month. At the Massachusetts Sierra Club, that same storm was the first thing chapter director Emily Norton cited to explain her belief that expanding Boston's natural-gas infrastructure is a mistake. 

"We’ve just seen this extraordinary storm in Boston with dumpsters floating down streets," Norton said. "It’s just a reminder of how vulnerable Boston is to climate change. Knowing that, I would think that Boston would want to be leading." 

For the record, Mayor Marty Walsh says Boston is leading when it comes to climate change and the environment. Case in point: his administration's ambitious Climate Action Plan, which calls for a 25 percent reduction in greenhouse gases by 2020, and carbon neutrality by 2050.

As Norton sees it, though, those goals will be hard to reach if Boston keeps increasing its reliance on fossil fuels.

"There’s 70 million square feet of development planned for the city of Boston in the future that we know of," Norton said. "If the plan is to have all of that powered by natural gas, that just does not compute."

Back in October, the Boston City Council seemed to agree. In a unanimous vote, it urged Boston’s Public Improvement Commission (PIC) to delay giving the pipeline extension a go-ahead.

But in December, the PIC — whose mandate is monitoring the impact of public works projects on public ways — green-lit the project. 

While the opponents have been vocal, some in the neighborhood believe the city made the right call.  

"A lot of our systems are old, and require older technology," said Meg Mainzer-Cohen, the head of the Back Bay Association. 

The Walsh Administration is already taking a number of meaningful steps to make Boston greener, Mainzer-Cohen added. But right now, she thinks denying new developments access to an established utility just isn’t realistic.

"It’s somewhat like saying the technology for automated vehicles is here, so nobody’s allowed to drive their cars," she said.

"There’s lot of agreement down the road that we’d like to see more energy options, cleaner energy options. The case I’ve been making is that we’re not quite there yet."

But Emily Norton argues that if that assessment is correct, it's because political will is lacking. 

"There’s got to be other solutions out there, but we’re not even telling people to go look," said Norton. "If you’re a developer, you just want to keep doing things the way you’ve always been doing [them]. If you’re National Grid, obviously you want to keep selling your gas. So unless we push back, we’re never going to get to a different place."

A spokeswoman for Boston Mayor Marty Walsh reiterated the city's commitment to its climate-change goals, and said a new initiative will allow more input on the energy building's use. But she declined to say whether Walsh backs the pipeline extension.