Methane is a potent greenhouse gas with a greenhouse potential over 20 times more effective in irradiating heat than CO2. As methane is one of the main products generated from buried organic matter during sedimentary basin evolution, and in view of the vast masses of carbon in the geosphere, the question arises whether leakage of methane from the geosphere to the atmosphere may affect global climate both at present and in the past. A group of GFZ scientists araound L.Berbesi addresses this question in an article appearing in the February 2014 edition of Earth and Planetary Science Letters, by combining the quantitative numerical simulation of basin evolution and methane generation with geochemical mass balance models and published measured natural methane emission rates.  

The GFZ researchers investigated both the burial and temperature controlled generation of methane as well as the formation of secondary methane by the biological degradation of petroleum in reservoirs. The results of this study indicate that vast amounts of methane are generated in the subsurface, but over geologic timescales. In essence total subsurface methane generation and leakage rates calculated for different sedimentary basins are at least five orders of magnitude lower than those expected to be necessary to exert significant climate effects. Global scale extrapolation of these rates of gas generation indicates that subsurface generation of methane, as a single process, would not be able to drive climate changes at geologic timescales. A mechanism promoting focused flow and sudden gas release from the reservoirs, such as gas hydrate formation and sudden decay, is required as a condition for petroleum systems to exert a significant effect on Earth’s climate.

Berbesi, L.A., di Primio, R., Anka, Z., Horsfield, B., WIlkes, H. (2014) “Methane leakage from evolving petroleum systems: Masses, rates and inferences for climate feedback”, Earth and Planetary Science Letters, 387, 219-228.