Carbon storage in soil parent materials - a source, a sink, or both?

 

Soils are an important component of the global carbon cycle. Ensuring and maintaining the ability of soils to sequester and store carbon is crucial for mitigating climate change. A large proportion of research to date has focused on carbon storage in the uppermost horizons of a soil profile. Meanwhile, the sequestration and storage of carbon in subsoils and underlying soil parent materials is an area that is only recently being studied. This presentation will evaluate the role of soil parent materials as long-term sinks for organic carbon, using recent empirical research across a range of ecosystems and lithologies. However, some soil parent materials could also represent important sources of petrogenic (i.e., rock-derived) organic carbon. Research currently being carried out on carbon-rich bedrock exposed by retreating glaciers in Switzerland will be used to highlight how petrogenic organic carbon, once mobilized into the soil profile during soil formation, could threaten net zero carbon targets. The presentation will conclude with a synthesis of the research gaps that require further attention by a multidisciplinary geoscience community.