New York passes landmark law to slash building emissions

The City Council passed a sweeping package of climate legislation on Thursday that set strict new limits on greenhouse gas emissions from New York's largest buildings, one of the most aggressive efforts by any city in the world to confront climate change.

The centrepiece of the Climate Mobilization Act required large buildings — those over 25,000 square feet, which together account for a major share of the city's emissions — to sharply cut their carbon output over the coming years or face steep fines. Buildings are the single biggest source of planet-warming emissions in New York, making them a natural target.

Supporters hailed the law as a national model, arguing that cities had to act as federal climate policy stalled. They said it would spur a wave of retrofits — better insulation, modern heating and cooling, and cleaner energy — creating jobs while cutting pollution.

Real estate groups warned that the mandates could prove costly and complex, particularly for older buildings and middle-income co-ops, and pressed for flexibility in how the targets were met.

The legislation was part of a broader "Green New Deal" for the city, and it put New York at the forefront of municipal climate action. Its real test would come in the years ahead, as thousands of building owners grappled with how to meet the new limits and the city built out the systems to enforce them.