He hammered that message even as the election required him to play a shifting set of roles. During the primary, he set himself apart from a field overflowing with progressives by showcasing his differences with the Democratic Party. During the general election, he became the consummate Democrat, earning the votes of the party’s most loyal voters even as the former governor and one-time old-guard Democrat Andrew Cuomo ran an independent bid. Fittingly, Mamdani’s victory speech Tuesday night alluded to and remixed lines from socialists and liberal Democrats alike — including Cuomo’s father, New York’s former governor Mario Cuomo.
“A great New Yorker once said that while you campaign in poetry, you govern in prose,” Mamdani said, paraphrasing the elder Cuomo. “If that must be true, let the prose we write still rhyme, and let us build a shining city for all.”
So given all the notes he struck during the campaign, it is revealing to consider those Mamdani left unplayed. One in particular stands out: Throughout the long mayoral campaign, Mamdani rarely spoke about climate change — often doing so only when directly asked.
This might not seem meaningful on its face. Mamdani had a lot of issues he could focus on, after all. (He also spoke intermittently about, say, K-12 education, even though as mayor he will oversee the nation’s largest school district.)
But in light of his biography, Mamdani’s relative reticence on climate change stands out. During his early career in the state legislature, Mamdani defined himself in part through his climate activism, and by his view that New York should be “leading the country in our fight against the climate crisis,” as he said in a 2022 press release. He helmed some of the most aggressive recent activist efforts to shut down, block, and replace fossil fuel infrastructure in Gotham. They provide a window into where his mayoralty could go — and also illustrate the fraught politics of climate change in Year 1 of Trump 2.0.
From his first days in the New York State Assembly in 2021, Mamdani placed himself at the forefront of the debate over the future of fossil fuels in New York’s energy system. “When I ran for this office, it was on a platform of housing, justice, and energy for all,” he said in a statement soon after his election.
Many of his biggest policy proposals as a legislator focused on climate change. He backed the Build Public Renewables Act, a bill that empowers New York’s state power agency to develop wind and solar projects in order to meet the state’s climate goals. He resisted NRG Energy’s push to replace an aging natural gas peaker plant in Astoria, Queens, with a newer power plant that would still burn gas. And he opposed the expansion of natural gas pipelines into the state while cosponsoring the Clean Futures Act, which would, he said, ban all new natural gas power plants across New York.
Climate change was the issue, he said, at the very heart of his political identity. In July 2022, after the state assembly expired without a vote on the Build Public Renewables Act and amid a heat wave in New York, he called for a special session to pass the bill, deeming climate change a “human catastrophe.”
“There are a number of bills that I would love to pass tomorrow. I’m not calling for a special session for all of them,” he told Spectrum News. “The reason we have to call for this one is because climate change is not waiting.”
In its fight against the Queens power plant, his legislative office — working alongside the Stop NRG Coalition, an alliance of local residents, the Democratic Socialists of America, and traditional environmentalists such as Earthjustice and the Sierra Club — called 36,000 households and sent more than 7,800 postcards asking residents to reject the plant, Mamdani later said. Ultimately, locals filed more than 6,000 comments to oppose the proposed plant; when the New York Department of Environmental Conservation ultimately denied a key permit in October 2022, Mamdani claimed victory.
He was also clear about who had lost that fight: big corporations and fossil fuel-aligned capitalism. “This shows when we organize against corporations that put capital over the collective, we can win a world where we all live with dignity,” he said. “Stopping the Astoria power plant is an amazing victory towards a habitable planet and the clean future we all deserve.”
Many of Mamdani’s other climate efforts were ultimately successful. The Build Public Renewables Act passed in April 2023 as part of the state budget and was signed into law by Governor Kathy Hochul. The state has not passed the Clean Futures Act, although regulators have rejected other proposed fossil-fuel power plants across the state, citing its 2019 climate leadership law.
In a little-watched May 2021 video that gives a concentrated dose of Mamdani’s political vision at the time, he described himself not as a socialist, but as a “proud ecosocialist” who believed that electricity should be treated as a “public good.”
“Did you ever wonder why New York state only gets 5% of its energy from wind and solar?” he asked in the video. “It’s because of one word: capitalism.” The way to fight that capitalistic hold on energy production, he said, was with public power — government ownership and development of zero-carbon generation.
Even after those victories, Mamdani remained a proud champion of climate issues. As recently as a year ago, he suggested that activism and agitation around climate change was a key way that progressives could differentiate themselves from Trump in the eyes of the working class. At a rally in late November last year, shortly after a drought resulted in a rare brush fire that consumed 2 acres of the city’s beloved Prospect Park, he exhorted the New York Power Authority, or NYPA, to move faster to develop its pipeline of renewables projects — and framed credible climate action as essential to countering Trump’s rise.
“The climate crisis does not care about any of the reasons that are usually given so much weight in Albany. It doesn’t care if you want to blame the supply chain. It doesn’t care if a private company says it has reduced profitability. It cares only if you build out renewable infrastructure,” he said.
“If you want to know how to defeat the Donald Trump far-right movement, it’s by showing we actually have a workable alternative,” he continued. “Because if working class people can’t breathe the air, if they can’t afford to live in the city they call home because they can’t find a union job, and if they look around at their favorite parks being on fire, why would they trust us?”
“It is time to show them why,” he concluded. “It’s time for the Build Public Renewables Act.”
Mamdani has continued to push for NYPA to accelerate its renewables construction — he posted a video of the same rally to his Instagram feed in September, encouraging his followers to file public comments with New York state.
As recently as February 2025, he described New York City as facing an “existential moment of our climate crisis” at a candidate forum, and said that enforcing the city’s climate laws would require “taking on the real-estate industry.”
But in the months since, his earlier bold rhetoric — casting practical concerns as no object when it comes to climate action — has faded, and he has evinced more sympathy for landlords and homeowners who may bear decarbonization’s costs. He still describes climate change in existential terms, but has become far less likely to bring it up unbidden in his own speeches and media appearances.
As a major party mayoral candidate, too, Mamdani largely avoided framing climate action as a necessary antidote to Trumpism. When seeking to contrast himself with the president, he focused almost entirely on cost of living issues. In a Fox News appearance in October, Mamdani addressed Trump directly and said that he would work with him to address New Yorkers’ cost of living.
His campaign website’s only stated climate proposal is a “Green Schools” plan to renovate 500 public schools, turn 500 asphalt schoolyards into green spaces, and construct “resilience hubs” at 50 schools. Speaking with The Nation in April — in one of his few recent long-form interviews on climate policy — Mamdani set that plan within his broader campaign, saying “climate and quality of life are not two separate concerns. They are, in fact, one and the same.” Schools, he said, offer “an opportunity for comprehensive climate action.”
But his website has few other details about what climate actions he might like to pursue once he takes office as mayor. Indeed, the candidate who once blamed capitalism for New York’s failure to build renewables is now promising to establish a “Mom-and-Pop Czar” to cut fines on small businesses and speed up permitting. It also gives few clues about how Mamdani would handle decarbonization’s inevitable trade-offs. If achieving a faster renewables buildout led to higher energy prices for consumers and small businesses, what would he do?
Even in situations where his slogans could reasonably connect to some climate benefit, Mamdani did not complete the handshake. His website does not mention the pollution benefits of fast and free bus service, for instance, even though free transit in other campaigns has been described as a climate policy. His 25-minute victory speech, delivered to a jubilant crowd on Tuesday night, did not mention climate change at all.
Regardless of what he’s said, Mamdani will be required to take big actions on climate policy as mayor. The most significant will likely arise from an ordinance called Local Law 97, which requires New York City’s large buildings to reduce their greenhouse gas emissions by 2050. That law’s strict new set of pollution caps and penalties will start in 2029, and many landlords are set to pay big fines. During the second mayoral debate, Mamdani repeated that the “climate crisis is one of the most pressing issues facing this city,” and said he wants the law’s fines to be enforced. But he also added that “the city should make it easier for buildings to comply.”
Mamdani has also argued that the city and state should renew a set of tax breaks to make it cheaper for large residential buildings, like condos and co-ops, to meet the law’s targets, and has proposed creating a “one-stop shop” for Local Law 97 compliance in the city governance, according to his debate remarks and a memo about homeowner policy released by his campaign.
In replacing climate change with cost of living, Mamdani has moved closer to what appears to be an emerging consensus among his party. Recent autopsies of the 2024 election have argued that voters believed Democrats were too focused on issues like climate change and not enough on affordability or inflation. Mamdani’s relentless focus on near-term costs — and his embrace of clear, actionable, and frankly non-climate-related slogans — suggests that one young ecosocialist might now agree with them. His ultimate victory suggests that it wasn’t a bad gamble.
