A tale in three pictures.
Below, see Northern Hemisphere methane (ppbv) in December of 2011, followed by methane levels in January 2012.
Finally, for comparison, I've added Northern Hemisphere methane levels from January 2003.
Graphics from by Dr. Yurganov, Senior Research Scientist, Joint Center for Earth SystemsTechnology, Atmospheric Remote Sensing, University of Maryland Baltimore County.
For animations of year-to-year methane levels, by month, visit here.