Methane

Catalysis

Climatology

Natural gas

Engineering

Ecology

Fugitive emissions

Biology

Biochemistry

Carbon monoxide

Earth science

East coast

Geology

Oceanography

Waste management

Greenhouse gas

Organic chemistry

Methane gas

Environmental science

Methane emissions

Chemistry

Atmospheric sciences

Carbon dioxide

Geophysical Research Letters

Urban emissions remain an underexamined part of the methane budget. Here we present and interpret aircraft observations of six old and leak‐prone major cities along the East Coast of the United States. We use direct observations of methane (CH 4 ), carbon dioxide (CO 2 ), carbon monoxide (CO), ethane (C 2 H 6 ), and their correlations to quantify CH 4 emissions and attribute to natural gas. We find the five largest cities emit 0.85 (0.63, 1.12) Tg CH 4 /year, of which 0.75 (0.49, 1.10) Tg CH 4 /year is attributed to natural gas. Our estimates, which include all thermogenic methane sources including end use, are more than twice that reported in the most recent gridded EPA inventory, which does not include end‐use emissions. These results highlight that current urban inventory estimates of natural gas emissions are substantially low, either due to underestimates of leakage, lack of inclusion of end‐use emissions, or some combination thereof.

Large Fugitive Methane Emissions From Urban Centers Along the U.S. East Coast