Figure 1 - Unexpected rise in global methane levels.
From the following article
Nature Reports Climate Change (2009) Published online: 5 March 2009
doi:10.1038/climate.2009.24
The average atmospheric concentration of methane shot up suddenly in 2007, having remained stable for a decade. Data shown are from the Advanced Global Atmospheric Gases Experiment and the Australian Commonwealth Scientific and Industrial Research Organisation, courtesy of Matt Rigby.
