Lead supervisor: Rachael Rhodes, Earth Sciences
Co-supervisor: Francesco Muschitiello, Geography; Alex Archibald, Chemistry; Gerd Folberth, Met Office
Brief summary:
Using a combination of earth system modelling and ice core data we will study feedbacks between the global methane cycle and climate.
Importance of the area of research concerned:
Methane is a much more potent greenhouse gas than carbon dioxide. It also has a relatively short atmospheric lifetime, making it an appealing option for rapid mitigation of climate change. However, methane levels in the atmosphere are currently increasing rapidly. There are significant uncertainties in predictions of what this means for the future evolution of methane and climate. We lack both understanding of the global methane budget and –critically– the positive feedbacks between climate and the methane cycle. Recently, measurements of ancient air trapped within ice cores have revealed unexplained atmospheric methane variations over multi-decadal timescales throughout the Holocene and Last Glacial period. It is unclear how this mode of variability may be linked to the enigmatic fluctuations in methane growth rate observed since the 1980s. One potential explanation is that feedbacks between the climate system, particularly in tropical regions, and methane production in wetlands are responsible for the observed variability. It is important to test this hypothesis and assess its importance for the methane cycle and its interaction with climate past, present and future.
Project summary :
The purpose of this project is to explore, and ultimately quantify, feedbacks between climate and wetland methane emissions over timescales relevant to our immediate future. This project will leverage earth system model simulations, and detailed records of past atmospheric methane variability from ice cores in Antarctica and Greenland will be used to constrain results.
What will the student do?:
This studentship is linked to the major international Fetch4 project (https://fetch4.github.io/) which aims to improve our understanding of the methane cycle. The student will work closely with researchers from the Met Office and the National Centre for Atmospheric Sciences (NCAS) in Cambridge to run numerical models ranging in complexity from box modelling to the state-of-the-art UK Earth System Model that has a fully interactive wetland methane emissions scheme (UKESM1-ems). Model experiments will be conducted for pre-industrial conditions and other key palaeoclimate intervals such as the Last Glacial and/or the Last Interglacial. Model simulations will be analysed to identify dominant timescales of methane variability, its amplitude and spatial variation, with results being compared to ice core data. In particular, the student will focus on attribution of methane emissions variations to climate and hydro-climate dynamics in the mid-to-low-latitude and large-scale climate modes, such as El Niño Southern Oscillation, as well as quantifying so far understudied wetland methane–climate feedbacks.
References - references should provide further reading about the project:
Folberth, G.A., Staniaszek, Z., Archibald, A.T., Gedney, N., Griffiths, P.T., Jones, C.D., O’Connor, F.M., Parker, R.J., Sellar, A.A., Wiltshire, A., 2022. Description and Evaluation of an Emission-Driven and Fully Coupled Methane Cycle in UKESM1. Journal of Advances in Modeling Earth Systems 14, e2021MS002982. https://doi.org/10.1029/2021MS002982
Rhodes, R.H., Brook, E.J., McConnell, J.R., Blunier, T., Sime, L.C., Fain, X., Mulvaney, R., 2017. Atmospheric methane variability: Centennial scale signals in the Last Glacial Period. Global Biogeochem. Cycles 2016GB005570. https://doi.org/10.1002/2016GB005570
Turner, A.J., Frankenberg, C., Kort, E.A., 2019. Interpreting contemporary trends in atmospheric methane. Proceedings of the National Academy of Sciences 116, 2805–2813. https://doi.org/10.1073/pnas.1814297116
Applying
You can find out about applying for this project on the Department of Earth Sciences page.