Global carbon cycle feedbacks from massive volcanism

Carbon emissions to the atmosphere can trigger both positive feedbacks, adding further carbon to the atmosphere, and negative feedbacks, sequestering carbon in rocks or sediments. Over short timescales, a warming climate can liberate sequestered carbon stores and exacerbate climate change. Over geological timescales, negative feedbacks are thought to predominate, sequestering carbon, stabilizing the climate, and ensuring the Earth's surface remains habitable. However the processes, strength, and timescales by which both positive and negative feedbacks on carbon emissions operate all remain fiercely contentious, limiting our predictions of long-term future climate. Proxy records of past climate events record the sum total of both initial carbon emissions and feedbacks, but disentangling the contributions of the two has not, until now, been possible.

This project builds on brand new understanding of carbon emissions from the North Atlantic Igneous Province (NAIP). Large Igneous Provinces like the NAIP are often associated with global climate change; indeed the NAIP was emplaced coincident with the Paleocene-Eocene Thermal Maximum (PETM), an abrupt global warming and ocean acidification event. A recent advance in the modelling of the sill emplacement by the plume head which fed the NAIP has allowed us to constrain thermogenic methane generation on palaeoclimate-relevant timescales. Knowing the rates of NAIP methane and carbon dioxide emissions is of critical importance in judging between this and other hypothesised mechanisms of carbon release triggering the PETM. The project will use the intermediate complexity Earth system model cGENIE to compare our new, realistic NAIP carbon emission histories to sedimentary records of climate, warming, ocean acidification, and weathering. Using inversion modelling techniques, the student will quantify the strength and timing of both short-term positive carbon cycle feedbacks as well as long-term negative carbon cycle feedbacks.

This project will suit a numerate graduate in any branch of Earth Sciences, Environmental Sciences, or Physical Geography. Although full training in project-specific modelling techniques will be provided, previous experience using Earth system models or climate models and/or coding experience will be advantageous.