There have been several recent papers exploring the growth in methane that has been ongoing since 2007. In a new paper in PNAS, we explore whether changes in the global OH concentration could be playing a role. By looking at trends in methyl chloroform, we infer an intriguing rise and fall in OH over the last 20 years, which could explain some of the methane change. There are significant uncertainties remaining, and much more work is needed before we can determine with confidence the role of changes in both methane sources and sinks. This is the focus of the new UK-wide NERC-funded MOYA project which will be on-going for the next three years.
There’s a University of Bristol news item, which provides more details on this story. The paper can be found here: Rigby et al., Role of atmospheric oxidation in recent methane growth, PNAS, doi:10.1073/pnas.1616426114, 2017