TIBETMETH

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

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 Obiettivo del progetto (Objective)

'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.'

Introduzione (Teaser)

The solution to understanding the role of microorganisms in climate change and carbon cycling may lie in the peatlands of the Tibetan Plateau.

Descrizione progetto (Article)

Knowledge of terrestrial microbial processes is crucial for accurate climate change predictions, as they regulate greenhouse gas (GHG) emissions, and therefore potentially important earth system feedbacks. However, these processes are not yet fully understood, resulting in uncertainty when determining how they will affect the climate and atmosphere in the future.

The EU-funded TIBETMETH project addressed an aspect of this challenge by studying organisms involved in carbon cycling in the Tibetan Plateau of central Asia. Researchers investigated key hydrological indicators and quantified biomarker tracers for different organisms that lived in the peat bog over the past 6000 years.

Links between precipitation, vegetation, redox conditions and microorganism-controlled processes, especially methane production (methanogenesis), were also determined. Methane was studied as it is an important GHG.

The aim was to gain a clearer understanding of the production and use of methane by bacteria and other living organisms. This was achieved with the aid of state-of-the-art chromatography and mass spectrometry technology.

Results showed how changes in the Asian monsoon affected emissions of methane from the Tibetan Plateau. During relatively dry intervals the biomass of methane-producing microorganisms decreased, while methane-consuming microorganisms appeared to become more efficient.

Other researchers have hypothesised that as the Asian monsoon became weaker over the past 6 000 years, methane emissions were also reduced. Results from TIBETMETH revealed that this is precisely what happened on the Tibetan Plateau.

TIBETMETH also suggested that the dry interval studied was due to large-scale changes in atmospheric circulation patterns. Therefore, just as past changes influenced methane emissions, so too could future climate change.

Data from the project will give scientists a clearer picture of how changes to the Asian monsoon affect both modern and ancient methane biogeochemistry. This information will ultimately become part of a framework of known and hypothesised relationships between microorganisms and climate change.