Extensive release of methane from Arctic seabed west of Svalbard during summer 2014 does not influence the atmosphere

Abstract

Abstract We find that summer methane (CH 4 ) release from seabed sediments west of Svalbard substantially increases CH 4 concentrations in the ocean but has limited influence on the atmospheric CH 4 levels. Our conclusion stems from complementary measurements at the seafloor, in the ocean, and in the atmosphere from land‐based, ship and aircraft platforms during a summer campaign in 2014. We detected high concentrations of dissolved CH 4 in the ocean above the seafloor with a sharp decrease above the pycnocline. Model approaches taking potential CH 4 emissions from both dissolved and bubble‐released CH 4 from a larger region into account reveal a maximum flux compatible with the observed atmospheric CH 4 mixing ratios of 2.4–3.8 nmol m −2 s −1 . This is too low to have an impact on the atmospheric summer CH 4 budget in the year 2014. Long‐term ocean observatories may shed light on the complex variations of Arctic CH 4 cycles throughout the year.