Rapid oceanographic switch play a role on the methane cycle
Large amounts of methane – whether as free gas or as solid gas hydrates – can be found in the sea floor along the ocean shores. When the hydrates dissolve or when the gas finds pathways in the sea floor to ascend, the methane can be released into the water and rise to the surface to reach the atmosphere, where it acts as a very strong greenhouse gas. Fortunately, marine bacteria exist that consume part of the methane before it reaches the atmosphere.
An international team of researchers led by the University of Basel, the GEOMAR Helmholtz Centre for Ocean Research in Kiel and in collaboration with the Institute for Marine and Atmospheric research Utrecht, studied large methane seeps along the coast of Spitsbergen. They showed that large bacteria populations cannot develop in a strong current, which consequently leads to less methane consumption. Ocean currents play therefore an important role on the methane cycle and thus on the amount of methane possibly emitted to the atmosphere.
This finding clearly shows that one-time or short-term measurements would only give us a snapshot of the methane emission or removal, but that in the future, fluctuations of bacterial methane consumption caused by oceanographic parameters will have to be considered, both during field measurements as well as in models.
Steinle, L., C. A. Graves, T. Treude, B. Ferré, A. Biastoch, I. Bussmann, C. Berndt, S. Krastel, R. H. James, E. Behrens, C. W. Böning, J. Greinert, C.-J. Sapart, M. Scheinert, S. Sommer, M. F. Lehmann, H. Niemann (2015): Water column methanotrophy controlled by a rapid oceanographic switch. Nature Geoscience