Atmospheric observations of Arctic Ocean methane emissions up to 82° north

E. A. Kort,

S. C. Wofsy,

B. C. Daube,

M. Diao,

J. R. Spackman and

Abstract

Uncertainty in the future atmospheric burden of methane, a potent greenhouse gas¹, represents an important challenge to the development of realistic climate projections. The Arctic is home to large reservoirs of methane, in the form of permafrost soils and methane hydrates², which are vulnerable to destabilization in a warming climate. Furthermore, methane is produced in the surface ocean³ and the surface waters of the Arctic Ocean are supersaturated with respect to methane^4, 5. However, the fate of this oceanic methane is uncertain. Here, we use airborne observations of methane to assess methane efflux from the remote Arctic Ocean, up to latitudes of 82° north. We report layers of increased methane concentrations near the surface ocean, with little or no enhancement in carbon monoxide levels, indicative of a non-combustion source. We further show that high methane concentrations are restricted to areas over open leads and regions with fractional sea-ice cover. Based on the observed gradients in methane concentration, we estimate that sea–air fluxes amount to around 2 mg d⁻¹ m⁻², comparable to emissions seen on the Siberian shelf. We suggest that the surface waters of the Arctic Ocean represent a potentially important source of methane, which could prove sensitive to changes in sea-ice cover.