This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Methane emissions from the New York City metropolitan area are largely driven by natural gas use, according to a new study published today in Atmospheric Chemistry and Physics by researchers at the Lamont-Doherty Earth Observatory, part of the Columbia Climate School. The findings may offer cities an overlooked pathway for reducing methane emissions while potentially saving consumers millions of dollars lost to wasted natural gas.
The researchers estimate that methane emissions associated with natural gas were approximately 1.7% of all gas delivered through the system. These emissions represent a substantial amount of fuel NYC consumers are paying for but not fully using, equivalent to nearly $300 million of natural gas, based on 2023 and 2024 retail prices. Methane is a powerful greenhouse gas, with more than 80 times the global warming potential of carbon dioxide over a 20-year timescale.
Because methane remains in the atmosphere for only about a decade, cutting its emissions may be a quick way to slow near-term global warming. "This study shifts the focus from underground pipeline leaks as a source of methane emissions to how natural gas is used in buildings, particularly how efficiently appliances burn it," said lead author Yuwei Zhao, a Ph.D. student in Columbia's Department of Earth and Environmental Sciences. The study provides the first monthly analysis tracking methane emissions before and after natural gas reaches customers in the NYC metropolitan area.
The researchers' methods enabled them to distinguish between natural gas released without combustion—either from leaks in underground utility pipes or from building appliances—and inefficiently burned gas from heating and cooling systems. To track those emissions, the researchers analyzed two years of hourly methane observations from the Mineola Tower, a National Institute of Standards and Technology monitoring site on Long Island. The tower is positioned to sample air flowing out of Manhattan and western Long Island during westerly winds.
The study team used data from January 2023 through December 2024 to capture seasonal patterns. Zhao and her colleagues also conducted intensive measurement campaigns at the tower in summer 2023 and winter 2024, measuring methane, ethane and carbon monoxide at high frequency. This allowed them to chemically identify and separate raw natural gas leaks from the incomplete combustion occurring in buildings.
The measurements revealed a distinct seasonal cycle: Methane emissions peaked during the winter heating season, declined through spring and rose again during the summer cooling season before increasing further during the following heating season. Natural gas accounted for 99% of total methane emissions in February and 98% in May, and 85% to 88% during the summer cooling months. "We expected winter heating to dominate methane emissions, but the summertime signal showed us that we need to be tracking these emissions year-round," said co-author Róisín Commane, associate professor in Columbia's Department of Earth and Environmental Sciences and a researcher at the Lamont-Doherty Earth Observatory.
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