A major new study published in Reviews of Geophysics^* in December 2010 puts the spotlight on methane emissions from natural sources and asks the question, how might they both affect and be affected by future climate change.

On 1^st October in Mexico City, 38 countries launched a Global Methane Initiative to drive down emissions of this potent greenhouse gas.

Arctic and Antarctic ice cores provide a rich source of evidence that both temperature and atmospheric concentrations of methane and carbon dioxide have fluctuated over the past 800,000 years. These studies have also shown that the fluctuations are cyclic, and that higher temperatures are generally associated with higher levels of methane and carbon dioxide in the atmosphere.

‘Methane ice’ has been hitting the headlines in the wake of the Deepwater Horizon drilling rig disaster in the Gulf of Mexico, and the complex issues relating to methane hydrate formation and occurrence have been brought to the attention of a wider public as a result of BP’s effort to contain the oil spill and limit the associated damage.

The murky, smelly sediments at the bottom of a canal or ditch might not be the obvious place to find a novel form of bacterial life which prompts questions about the early evolution of metabolism, the nature of the biological methane sink, or the possible role of man-made pollution in creating a microbe which ingeniously generates its own fuel supply.

Geophysicists have long used subtle local variations in the earth’s measured gravity field to help build a picture of subsurface geological structures.  A team led by MethaneNet colleague Professor Paul Palmer at Edinburgh University has now pioneered a new use of gravity anomaly data to constrain estimates of methane emissions from different wetland areas (Bloom et al., 2010).

Words by Anna Pigott, image by 'LakeRae'

During 2007 and 2008 concentrations of atmospheric methane increased after a decade of near-zero growth.