TIBETMETH · Microbial Biomarker Records in Tibetan Peats: Monsoon Variability and its Impact on Methane Biogeochemistry

It is crucial to understand terrestrial microbial processes because they govern greenhouse gas emissions; unfortunately, the long-term microbial responses to climate change remain unclear, causing uncertainty in predictions for how they will impact future climate and atmospheric composition. The peatlands from the Tibetan Plateau, controlled by the Indian Monsoon and East Asian Monsoon systems, have been major players in climate change and carbon cycling, such that these deposits represent a truly novel potential to address the above scientific issues. This proposed research will expand the Tibetan Plateau dataset of peat-forming plant δD values, a key hydrological indicator; quantify and isotopically characterise microbial biomarkers and especially those derived from organisms involved with methane cycling; evaluate the link between precipitation, vegetation, redox conditions and microbially mediated processes and especially methanogenesis. These records will be developed using cutting edge approaches exploiting gas chromatography (GC), GC-mass spectrometry, high performance liquid chromatography-mass spectrometry, GC-isotope ratio mass spectrometry (IRMS) and GC-thermal conversion-IRMS. This dataset seeks to understand methanogenic and methanotrophic processes and will be used to develop higher resolution and longer-term CH4 biogeochemical records over the Holocene and to better understand the effect of Asian monsoon change on modern and ancient CH4 biogeochemistry, and to ultimately embed them in the framework of known and hypothesised relationships between microorganisms and climate change. This work will be one of the very first applications of these novel methodologies to the study of past changes in peat biogeochemistry outside of Northern Europe. It will validate and expand on the European investigations and contribute to a better mechanistic understanding of the microbial response to climate change and its impact on CH4 biogeochemistry.