A new study published in Atmospheric Chemistry and Physics reveals that methane emissions in the New York City metropolitan area are largely driven by the use of natural gas. Conducted by researchers at the Lamont-Doherty Earth Observatory, part of the Columbia Climate School, the study found that methane emissions linked to natural gas accounted for about 1.7% of all gas delivered through the system. At current retail prices, this loss translates to nearly $300 million worth of natural gas annually. Methane is a powerful greenhouse gas, with a global warming potential over 80 times greater than carbon dioxide over a 20-year period. To track methane emissions, the researchers conducted the first monthly analysis of methane levels before and after natural gas reaches customers in the NYC area. They used two years of hourly methane observations from the Mineola Tower, a monitoring site on Long Island managed by the National Institute of Standards and Technology. This location is ideal for sampling air moving from Manhattan and western Long Island during westerly winds. The study covered data from January 2023 to December 2024, capturing seasonal changes, and included intensive measurement campaigns in the summer of 2023 and winter of 2024. During these periods, the team measured methane, ethane, and carbon monoxide at high frequency. The study identified a clear seasonal pattern in methane emissions. Emissions spiked during the winter heating season, dropped in spring, and rose again during the summer cooling season, increasing further in the next heating season. Natural gas was responsible for 99% of total methane emissions in February and 98% in May, and between 85% and 88% during the summer months. Researchers identified incomplete combustion by looking at the correlation between methane and carbon monoxide, a byproduct of inefficient burning. Only 6% of natural gas plumes in winter and 7% in summer showed no signs of combustion, suggesting that pipeline leaks were less common than emissions from incomplete burning. The study helps explain why methane emissions in the New York area have been higher than national and global estimates. Previous research has found two to five times more methane emissions than expected, even after efforts to fix pipeline leaks. The findings suggest that inefficient use of natural gas, such as incomplete combustion, accounts for much of the discrepancy and should be considered in future methane calculations. The researchers also noted that methane emissions closely followed real-time natural gas deliveries, reinforcing the idea that emissions are mainly driven by natural gas use after it reaches consumers. Some buildings use natural gas for cooling, which may explain the rise in emissions during summer months. While methane was also detected from wetlands, wastewater treatment plants, and landfills, these sources had a relatively small impact on the region’s overall emissions. As global temperatures rise and extreme weather events become more frequent, the demand for both heating and cooling is expected to increase. If cities continue relying heavily on natural gas to meet this demand, methane emissions could rise further. However, the study suggests that reducing these emissions could offer a significant opportunity for near-term climate action. By addressing inefficient combustion and transitioning to cleaner energy sources, urban areas may be able to mitigate a major source of greenhouse gas emissions.