NEW YORK — Thousands of people massed along Central Park in what might have seemed like a procession for one of many holiday parades that pass through this city. And while the mood was festive, the cause was more solemn — act now on climate change, or face the consequences.

Those assembled in New York for the People's Climate March, organized by a handful of environmental and left-wing groups that borrowed, in some respects, from the Occupy movement, pressed politicians, investors, corporations, faith organizations and others to address rising greenhouse gas emissions, which most scientists say warms the planet.

The event was held on the eve of the United Nations climate summit. Observers expect rhetoric to be on high, but there's likely to be a shortage of new, concrete commitments from some of the world's largest and most carbon-emitting countries.

Organizers said the march, which they estimated brought in more than 310,000 people — the New York City Police Department doesn't tender crowd estimates — was designed to give a face to the movement of people calling for action to address climate change, and to show the diversity of the groups that want leaders to take those steps.

"People are going to go back home and they're going to see this is an issue," said Van Jones, President Obama's former green jobs adviser.

But there's still a question of how to build out support across more moderate and conservative elements. Such people, save for a few faith-based groups, largely weren't present.

The U.S. political figures present of for the march in New York were many of the usual suspects. Sen. Sheldon Whitehouse, D-R.I., who makes weekly speeches on the Senate floor about climate change, was marching in the VIP section. So, too, was Sen. Bernie Sanders, I-Vt. Rep. Keith Ellison, D-Minn., an embodiment of the progressive Left, said that had his conservative colleagues attended, they "wouldn't be able to leave here without being changed," but that the real work would start after the march.

"You're going to have all these people organizing, gathering in, getting educated, mobilizing, sensitized, inspired," Ellison told the Washington Examiner. "And then you send them out, kind of like a good virus in a way."

Tom Steyer, the billionaire climate activist and former hedge fund manager, was there as well, wearing a hat and blue button-down shirt pocked with sweat early in the morning. He said that the event showed that climate change can't be "swept under the rug" anymore.

"I think that as much as we like like to think we are the center of the universe, we need to get it right for ourselves first," Steyer, whose NextGen Climate Action PAC is hitting GOP candidates in several Senate and gubernatorial races, told reporters of creating climate momentum both domestically and internationally, a nod to the U.N. summit here on Tuesday.

The U.N. summit isn't a part of the formal climate negotiating process. Instead, it's meant to breathe life into those talks next year in Paris following deflating 2009 negotiations in Copenhagen, where nations left without a treaty to secure enough carbon cuts by 2020 to avoid a 2 degrees Celsius temperature rise by 2100. Paris is viewed as a last-ditch effort to strike such a deal.

Activists maintained they're making inroads outside the traditional environmental community. Labor unions, indigenous communities, minority organizations and faith groups were all represented. In a media sheet handed out to reporters, contacts for politicians, environmental groups and celebrities were in the back, a move meant to underscore the broader, grassroots tone the event strove to strike.

Those participating in the rally on this thickly humid and overcast day in New York weren't focused so much on specific actions, events or negotiations. The emphasis was on volume, both in number and decibel, as marching bands peppered the procession and cheers and chants erupted throughout.

"It's good to see the wide range of folks — not only ages, but diversity and the different kind of concerns folks have, which is good. I think if you're going to have a successful climate movement, you've got to have everybody on board," August Ritter, 28, of Washington, told the Examiner.

Kimberly Shepherd, a 30-year-old mother from a coal-mining town in Harlan County, Ky., said it's important for her and others to show up to events like the one in New York.

Moving the dialogue in her hometown can often be frustrating, she said. Climate change isn't a popular topic, and many are convinced coal-mining would be on the rebound were it not for Obama administration environmental regulations — even though coal jobs in the region have been on the decline for decades.

Therefore, Shepherd thinks it's important to work on both the national pressure as well as local. Then, she said, the candidates vying for Kentuckians' political support might be more honest with their constituents about the future of the coal-mining industry.

"People believe that coal-mining is coming back. … They're being misled," Shepherd told the Washington Examiner. "I don't think it's really fair to them. They just want to work and sustain their families like everyone else does."

Organizers stressed that it's more than marching — participating groups are taking action to tamp down emissions and confront climate change. Some investors have shifted toward more climate-friendly assets. A handful of university endowments have untangled investments with fossil fuel firms. Some institutional lenders and foundations plan to announce they're withdrawing dollars from such companies this week.

That's largely because people aren't counting on Congress. Given the lack of conservative politicians and Republicans at the event and years of gridlock on the environment — a dynamic aided by many GOP lawmakers being skeptical of man-made climate change — on Capitol Hill, Jones said that is the most prudent option.

"If you're waiting for Washington, D.C., to act, you're going to be waiting for a long time," Jones said. "Washington, D.C., is stuck on stupid, The country's not. We're moving forward."