What are you like? The composition of organic matter, its reactivity and its relevance to the global carbon cycle and climate

Earth Surface Science Institute seminar. Speaker Professor Richard Pancost, University of Bristol.



On very long timescales, the Earth's climate is governed and regulated by a range of processes, including the chemical weathering thermostat. However, on shorter timescales, from hundreds to tens of thousands of years, the organic component of the carbon cycle is critical.  The burning of fossil fuels, oxidation of soil organic matter (OM), and the rapid burial of OM during times of widespread ocean anoxia have all been invoked as mechanisms for a relatively rapid change in the global carbon cycle, often with widespread knock on effects across the Earth system. These processes can be interrogated in modern and ancient contexts with both top-down or bottom-up approaches, by either examining the global (typically carbon isotopic) fingerprint of OM release/burial or deciphering the underlying mechanisms that govern OM preservation or oxidation.  I'll try to explore both, drawing on lessons learned by studying many of the carbon cycle perturbations of the Phanerozoic but also the characterisation and reactivity of OM in various settings, especially in source to sink contexts where the fate of terrestrial OM is... complicated.  Although the reactivity of OM is governed by its chemical structure, its preservation (or not) is ultimately contingent on environmental conditions. Fully appreciating those is vital to understanding future carbon cycle feedbacks.


About the speaker

Professor Pancost is Professor of Biogeochemistry at the University of Bristol and Head of the School of Earth Sciences.  He was a co-founder, and for the past the past five years, the Director of the Cabot Institute, which engages interdisciplinary approaches to address the major environmental and sustainability challenges of the 21st century.  He obtained his PhD at Penn State University in 1998 and has been at the University of Bristol since 2000. He is an organic geochemist and co-lead of Bristol’s Organic Geochemistry Unit, applying state of the art analytical methods to characterise organic matter in a range of environments. He applies these tools to explore how organisms mediate our planet’s chemical environment and uses their molecular signatures to reconstruct Earth’s past climate. These findings help constrain uncertainty in the Earth system but also to identify the unknown unknowns, including the deep uncertainty in how climate change will impact the social and natural ecosystems on which we depend. Via the Cabot Institute, he has worked across all disciplines and a range of stakeholders, to explore how cities can become more resilient and inclusive, and the requirements for achieving a carbon neutral future.