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

• Main Authors: Myhre, CL, Ferré, B, Platt, SM, Silyakova, A, Hermansen, O, Allen, G, Pisso, I, Schmidbauer, N, Stohl, A, Pitt, J, Jansson, P, Greinert, J, Percival, C, Fjaeraa, AM, O'Shea, SJ, Gallagher, M, Le Breton, M, Bower, KN, Bauguitte, SJB, Dalsøren, S, Vadakkepuliyambatta, S, Fisher, RE, Nisbet, EG, Lowry, D, Myhre, G, Pyle, JA, Cain, M, Mienert, J
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2016
• Subjects: 37 Earth Sciences; 3708 Oceanography; 3701 Atmospheric Sciences; 14 Life Below Water; Arctic; Arctic Ocean; Svalbard; Norway; Arctic Gas Hydrate, Environment and Climate; Climate change
• Online Access: https://www.repository.cam.ac.uk/handle/1810/255821

© 2016. American Geophysical Union. All Rights Reserved. We find that summer methane (CH4) release from seabed sediments west of Svalbard substantially increases CH4 concentrations in the ocean but has limited influence on the atmospheric CH4 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 CH4 in the ocean above the seafloor with a sharp decrease above the pycnocline. Model approaches taking potential CH4 emissions from both dissolved and bubble-released CH4 from a larger region into account reveal a maximum flux compatible with the observed atmospheric CH4 mixing ratios of 2.4-3.8 nmol m-2 s-1. This is too low to have an impact on the atmospheric summer CH4 budget in the year 2014. Long-term ocean observatories may shed light on the complex variations of Arctic CH4 cycles throughout the year. The project MOCA- Methane Emissions from the Arctic OCean to the Atmosphere: Present and Future Climate Effects is funded by the Research Council of Norway, grant no.225814 CAGE – Centre for Arctic Gas Hydrate, Environment and Climate research work was supported by the Research Council of Norway through its Centres of Excellence funding scheme grant no. 223259. Nordic Center of Excellence eSTICC (eScience Tool for Investigating Climate Change in northern high latitudes) funded by Nordforsk, grant no. 57001.