But doesn't the article suggest that the recent rapid rise comes from methane produced by microbes? If this is true, it is not the melting permafrost, but (intensive) agriculture that is the culprit.
> But since 2007, when methane levels began to rise more rapidly again, the proportion of methane containing 13C began to fall (see ‘The rise and fall of methane’). Some researchers believe that this suggests that much of the increase in the past 15 years might be due to bacterial sources, rather than the extraction of fossil fuels.
Isn't the methane in permafrost produced by microbes? It's basically wet lands that ended up being frozen, and as they thaw they go back to releasing the methane being processed by the breakdown of organic matter from microbes.
> But since 2007, when methane levels began to rise more rapidly again, the proportion of methane containing 13C began to fall (see ‘The rise and fall of methane’). Some researchers believe that this suggests that much of the increase in the past 15 years might be due to bacterial sources, rather than the extraction of fossil fuels.