Large Igneous Provinces (LIPs) are often associated with global climate change. The best-studied example is the association between the Paleocene-Eocene Thermal Maximum (PETM) and the North Atlantic Igneous Province (NAIP). The PETM is an abrupt global warming and ocean acidification event caused by a major carbon-cycle perturbation. The NAIP supplied carbon-based greenhouse gases to the atmosphere by two main mechanisms. Thermogenic methane formed when shallow igneous sills intruded sedimentary rock with an organic component, and reaches the atmosphere through hydrothermal vents. Carbon dioxide was released from both intruded and erupted magma. Knowing the rates of methane and carbon dioxide emission is of critical importance in judging between this and other mechanisms of carbon release in triggering the PETM.
Existing studies of the LIP methane source provide good estimates of the total mass of carbon released, but the temporal fluctuations in emission rate remain unclear. On the other hand, climate modelling studies have placed bounds on carbon emission rates that would be required to match observed warming and ocean acidification, but they cannot judge whether such rates could feasibly be delivered by the NAIP.
This project will build on work recently completed at the University of Birmingham to determine geologically reasonable methane emission rate scenarios for LIPs. The new framework has three key components. First, we have assembled a large database of sill and host-rock characteristics measured in well-explored parts of LIPs, including the NAIP. Secondly, we have developed a new parameterization of kinetic maturation modelling that permits rapid computation of methane and carbon dioxide generation and expulsion. Thirdly, we have incorporated cutting-edge research into the mantle melt generation processes to constrain rate of sill intrusion across the NAIP. Together, these innovations allow stochastic modelling of carbon-based gas emissions from a sill-and-lava province, in order to determine geologically realistic gas emission rate histories.
The project will use earth system modelling to link the new, realistic methane emission histories to sedimentary records of climate, warming, ocean acidification, and environmental change across the PETM. cGENIE, an Earth system model of intermediate complexity with state-of-the-art representations of biogeochemistry and carbon cycling, will be used to investigate how the estimated range of methane emission scenarios translates in sea surface and deep sea temperature, magnitude and duration of the carbon isotope excursion, difference between marine and terrestrial carbon isotope records, and changes in the patterns of ocean pH and deep sea carbonate burial. Emphasis will be placed on thoroughly exploring how the range of plausible methane emission scenarios maps into model predictions. Observations and modelling predictions will then be compared to assess the role of LIP-derived carbon-based greenhouse gases in forcing various climate change events, beginning with the PETM-NAIP association, then widening in scope to other cases.
Training and Skills
CENTA students attend 45 days of general training throughout their PhD, including a 10-day placement. In the first year, students will be trained as a single cohort in environmental science, research methods and core skills. During the PhD, training focus will progress from core skill sets to master classes more specific to the student's project.
This project will suit a numerate graduate in any branch of earth sciences. Although full training in project-specific LIP modelling techniques and climate modelling software will be provided, previous experience in computational techniques will be advantageous.
Although no field work is required for this particular project, the successful applicant will have the opportunity to participate in ship- and land-based expeditions linked to other projects in the Geosystems research group and wider collaborations.
Year 1: Familiarisation with new framework for determining LIP methane emission. Familiarisation with climate modelling software. Design climate modelling strategy; begin modelling work.
Year 2: Main phase of modelling to address PETM-NAIP association, leading to draft paper.
Year 3: Expend modelling to other LIP-climate change associations. Further paper. PhD dissertation.
Contact Dr Stephen Jones (firstname.lastname@example.org) or Dr Sarah Greene (email@example.com) for project-specific information. See CENTA web page for information on how to apply and general information (http://www.birmingham.ac.uk/generic/centa).