New York City's natural gas losses traced to furnaces and boilers, not pipeline leaks, study finds

A two-year atmospheric monitoring study centered on a tower in Mineola, New York, has found that New York City's natural gas system loses far more gas to the open air than regulators assume, and that the leading cause is not aging pipes underground but inefficient combustion inside buildings. The study, led by researchers at Columbia University's Lamont-Doherty Earth Observatory, estimates that about 1.7 percent of all the natural gas delivered to the city's metropolitan area escapes unburned into the atmosphere every year, equal to roughly $300 million worth of gas that customers pay for but never use.

The paper, "Inefficient consumption of natural gas drives methane emissions from a megacity," was published online September 14 in the European Geosciences Union journal Atmospheric Chemistry and Physics. It drew fresh public attention this week after Planetizen and other outlets reported on its findings. The underlying science, in other words, is a month old; what is new is the attention it is now getting as New York City households head into another heating season.

A loss rate three times larger than assumed

The research team, led by atmospheric chemist Yuwei Zhao with senior author Róisín Commane, both at Columbia's Department of Earth and Environmental Sciences and Lamont-Doherty, set out to explain a long-standing discrepancy: airborne, satellite and tower-based studies have repeatedly found that the New York City metropolitan area emits two to five times more methane than official inventories predict, without pinning down exactly why.

Using continuous measurements from a 62-meter instrument tower in Mineola, operated for the National Institute of Standards and Technology, along with two intensive field campaigns in the summer of 2023 and winter of 2024, the team tracked methane alongside two companion gases: ethane, which is unique to natural gas, and carbon monoxide, a signature of incomplete combustion. By comparing how tightly these gases rose and fell together in the air, the researchers could tell whether a given plume of methane came from a raw gas leak somewhere in the distribution system or from gas that had been partially burned, and then vented, inside a boiler, furnace or stove.

The result was a loss rate of 1.7 percent, plus or minus 0.6 percent, more than three times the 0.5 percent beyond-the-meter loss rate used in the most detailed regional emissions inventory for the area. Emissions peaked twice a year, once in winter when buildings burn gas for heat and again in summer when gas-fired cooling systems run hardest, a pattern the authors say reflects energy use rather than static pipeline leakage, which should stay roughly constant year-round.

Rooftops, not the street

The city's thousands of miles of underground gas mains, many of them decades-old cast iron and steel, have long been the focus of utility leak-repair programs and prior research into New York's methane problem. The new study does not clear pipelines of all blame, but it concludes that incomplete combustion downstream of the gas meter, inside the millions of furnaces, water heaters and stoves across the five boroughs, is the dominant and largely unaccounted-for source.

"Our results highlight the three dimensional nature of urban methane emissions: the largest methane emissions are observed from rooftops and not from the pipelines beneath the streets below."

That line, from the paper's conclusion, reframes where city and state agencies should look for fixes. Utilities such as Con Edison have spent hundreds of millions of dollars replacing old street-level pipe, a strategy the authors note has not meaningfully reduced measured methane emissions in Boston despite similar investment there. The Columbia team's comparison data show New York's 1.7 percent loss rate sits in the middle of a range reported for other U.S. cities: lower than the 2.5 to 2.7 percent found in Boston, but higher than the 1.3 to 2.3 percent estimated for Los Angeles and the 1.3 percent for Baltimore-Washington.

Why it matters for climate policy

Methane carries more than 80 times the warming potential of carbon dioxide over a 20-year horizon, according to figures the researchers cite from the Intergovernmental Panel on Climate Change, making it a priority target under the international Global Methane Pledge. Cities account for a disproportionate share of fossil methane emissions, and most mitigation programs to date have focused on production and pipeline infrastructure rather than how gas is actually burned once it reaches a building.

The study's authors argue that national and global inventories, including those compiled by the U.S. Environmental Protection Agency and international bodies, do not currently include any loss factor for inefficient combustion after the meter. If other cold-climate cities show a similar pattern, the finding could shift where regulators and utilities direct retrofit dollars, toward appliance efficiency and electrification rather than pipe replacement alone. The work was funded in part by the New York State Energy Research and Development Authority and the National Oceanic and Atmospheric Administration, whose Global Monitoring Laboratory supplied the calibration standards used to validate the tower measurements.

What happens next

The research team has made its underlying atmospheric data public through the Dryad repository, and the paper's authors say the next step is determining whether the combustion-driven loss pattern they found in New York holds in other dense, cold-weather cities with similar heating and cooling demands. For New York City specifically, the findings arrive as the city and state weigh how aggressively to pursue building electrification policies under New York's climate law, which aims to sharply cut greenhouse gas emissions from buildings over the coming decade. Whether utilities, regulators or building owners take up the appliance-efficiency problem the study identifies is, for now, an open question; the paper itself stops at diagnosis, calling only for future inventories and mitigation planning to "prioritize inefficient natural gas consumption" rather than pipeline leaks alone.