|2011-05-30 11:43:09||Anyone understand the significance of this?|
From Tamino's Methane Update post.
Is the d13CH4 the anthropogenically-derived methane? If so, then the melting permafrost and clathrates may be responsible for the overall rise in CH4 levels over the same period:
Check out the list of papers I gave in the comments, some of those are addressing the possible sources on the recent rise.
Its hard to know what to make of the 13CH4 record. Methane from melting permafrost is likely (I am speculating here) to be just as C13 depleted as CO2 from plants or fossil fuels since its source is decaying vegetable matter. Methane from Clathrates/Hydrates I would think is probably not as or at all 13C depleted but I can't be sure of that. It would need studies of the isotopic makeup at source to confirm the proportions.
Possibly the pattern of CH4 concentrations worldwide could be used to track down sources geographically - if there are enough reliable stations available.