Marine methane cycle simulations for the period of early global warming
Article first published online: 28 JAN 2011
Copyright 2011 by the American Geophysical Union.
Journal of Geophysical Research: Biogeosciences (2005–2012)
Volume 116, Issue G1, March 2011
How to Cite
2011), Marine methane cycle simulations for the period of early global warming, J. Geophys. Res., 116, G01010, doi:10.1029/2010JG001300., , , , and (
- Issue published online: 28 JAN 2011
- Article first published online: 28 JAN 2011
- Manuscript Accepted: 9 SEP 2010
- Manuscript Revised: 4 AUG 2010
- Manuscript Received: 18 JAN 2010
Vol. 116, Issue G3, Article first published online: 23 JUL 2011
 Geochemical environments, fates, and effects are modeled for methane released into seawater by the decomposition of climate-sensitive clathrates. A contemporary global background cycle is first constructed, within the framework of the Parallel Ocean Program. Input from organics in the upper thermocline is related to oxygen levels, and microbial consumption is parameterized from available rate measurements. Seepage into bottom layers is then superimposed, representing typical seabed fluid flow. The resulting CH4 distribution is validated against surface saturation ratios, vertical sections, and slope plume studies. Injections of clathrate-derived methane are explored by distributing a small number of point sources around the Arctic continental shelf, where stocks are extensive and susceptible to instability during the first few decades of global warming. Isolated bottom cells are assigned dissolved gas fluxes from porous-media simulation. Given the present bulk removal pattern, methane does not penetrate far from emission sites. Accumulated effects, however, spread to the regional scale following the modeled current system. Both hypoxification and acidification are documented. Sensitivity studies illustrate a potential for material restrictions to broaden the perturbations, since methanotrophic consumers require nutrients and trace metals. When such factors are considered, methane buildup within the Arctic basin is enhanced. However, freshened polar surface waters act as a barrier to atmospheric transfer, diverting products into the deep return flow. Uncertainties in the logic and calculations are enumerated including those inherent in high-latitude clathrate abundance, buoyant effluent rise through the column, representation of the general circulation, and bacterial growth kinetics.