UAV Test Puts Arctic Methane Seep Emissions at Up to 16.2 kg an Hour
Drone flights estimated a Canadian Arctic methane seep at up to 16.2 kilograms an hour. The July 2025 field campaign targeted a known geological methane seep in the Mackenzie River Delta in Canada. The result points to a single point source with emissions large enough to matter for Arctic methane accounting.
Two UAV platforms were used to sample the plume with different sensing packages. One carried an open-path greenhouse gas analyzer, while the other used a closed-path analyzer; the aircraft flew vertical curtain patterns through the downwind plume. Those flight paths created flux planes at different distances from the seep, allowing the study to compare instruments and measurement strategies under the same field case.
The work addresses a gap in Arctic monitoring. Eddy-covariance towers are fixed instruments that require long observation periods and reliable footprint modeling, while flux chambers cover small areas and can disturb the source being measured. UAVs can cross the spatial extent of a plume with limited disturbance, making them better suited to remote point sources where ground access and fixed infrastructure are difficult.
The study compared mass-balance estimates with Gaussian plume inversion, two common approaches for quantifying point-source emissions. Mass-balance methods produced the most robust estimates in this case and showed smaller uncertainties than the Gaussian plume approach. Across the flights and methods, the seep was estimated at 7.1 to 16.2 kilograms of methane an hour, with an average estimate of 11.4 ± 6.8 kilograms an hour.
The findings remain bounded by the test design. Public review comments noted that the dataset covered four flights at one site under one set of atmospheric conditions, with no independent ground-truth emission rate, and raised questions about wind measurements, background methane, pressure stability and water vapor effects. Even with those limits, the measured source was equivalent to the biogenic methane flux from about 2.2 km2 of surrounding permafrost landscape, underscoring the need to include geological seeps in regional and pan-Arctic carbon budgets.