Geophysical Research Abstracts, Vol. 7, 00077, 2005 SRef-ID: 1607-7962/gra/EGU05-A-00077 © European Geosciences Union 2005 Vertical pathways of methane in the Black Sea D. F. McGinnis (1), A. Wüest (1), J. Greinert (2), A. Lorke (3), C. J. Schubert (1) (1) Applied Aquatic Ecology, Swiss Federal Institute for Environmental Science and Technology (EAWAG), Kastanienbaum, Switzerland, (2) Leibniz-Institut fuer Meereswissenschaften IFM-GEOMAR, Marine Environmental Geology, Kiel, Germany, (3) Limnological Institute, University of Konstanz, Konstanz, Germany (dan.mcginnis@eawag.ch / Fax: +41 41 349 2168 / Phone: +41 41 349 2197) Introduction Methane, after carbon dioxide, is the second most important greenhouse gas in the atmosphere. Methane has 21 times the global warming potential as the same mass of carbon dioxide (St. Louse et al. 2000). Methane concentrations have doubled from 850 ppb to approximately 1750 ppb over the last 150 years (Cicerone and Oremland 1998). This concentration, however, would be even much higher if the huge methane pools that are stored in ocean and lake sediments would be released to the atmosphere. Current research has therefore focused on the atmospheric methane contribution from gas hydrates and seeps, a phenomenon that has been overlooked some 20-30 years ago (Kvenvolden 1988). In the Black Sea, measurements were performed on R/V Professor Vodyanitsky during the two CRIMEA (EC project EVK-2-CT-2002-00162) cruises, May - June 2003 and 2004. In the north western Black Sea, hundreds of active gas seeps were detected along the shelf and slope of the Crimea Peninsula at water depths between 35 and 800 m. Active gas seeps down to 2100 m water column were also detected. This portion of the CRIMEA project focuses on the fate of the methane resulting from both shallow and deep seeps. Results are presented detailing methane transport in the Black Sea due to 1) bubble transport, 2) methane-induced bubble plumes 3) vertical turbulent diffusion and 4) methane oxidation rates. These transport mechanisms allow us to estimate the conditions and means by which methane released from seeps reaches the surface.