Microbial methane in the crust - volumes, fluxes and consequences

Microbial production and consumption of the greenhouse gas methane in various environments influence the flux of methane to the atmosphere where it contributes to global warming, a major global environmental threat.

Our recent findings reveal widespread methane formation and consumption in one of the least understood ecosystems on Earth, the crystalline crust.

As this is one of the largest microbial habitats on Earth, an evaluation of the methane fluxes is needed, and negative environmental effects of gas seepage (natural and from exploitation or geothermal energy drillings), need consideration.

Outstanding questions about these deep biosphere processes include: At what rates is microbial methane formed and at what rates is it consumed by indigenous deep biosphere communities?

How widespread are the processes in time and space?, How large volumes of gas are there and how large is the microbial fraction? What energy sources, consortia and reduction/oxidation pathways dominate these deep biosphere processes?

To address these questions, analysis of isotopes in gases, minerals and microbial communities will be done along with incubation experiments from indigenous gas producing and consuming microbes.

The results will answer fundamental questions on deep gas volumes and fluxes, and allow definition of whether gas seepage may be significant in a global warming perspective. The scope that is highly relevant for several of the Swedish environmental objectives and UN’s Global Goals.