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Cambridge NERC Doctoral Training Partnerships

Graduate Research Opportunities
Importance of the area of research concerned: 
Methane is the second most important greenhouse gas after carbon dioxide. Its concentration in the atmosphere has been increasing more rapidly than expected recently, with grim implications for the goals of the UN Paris Agreement. The reason for this increase, following on from a period of near-zero growth, is uncertain. Both natural- and human-induced factors are likely to be involved and these are difficult to tease apart (1). The ancient air trapped inside ice core bubbles allows us to reconstruct the history of atmospheric methane and put current changes into context. Recently, persistent multi-decadal scale variations in atmospheric methane have been resolved through the Last Glacial period (2). Similar variability exists in the Late Holocene (3) and may even be related to the recently observed growth rate changes. To decipher this, and ultimately learn how future methane levels may evolve, records of ice core methane are needed to fill current data gaps in both time (early-mid Holocene) and latitude. Comparison of records from different latitudes can tell us about the spatial distribution of methane sources and how this varies over time.
Project summary : 
The main objective is to understand the natural- and human-induced controls on atmospheric methane variability over the Holocene, with a particular focus on multi-decadal scale signals. This will involve the development of a new ice core continuous gas measurement system and participation in several analytical campaigns to measure methane in ice cores from different latitudes. Previous attempts to measure methane in mid-latitude ice cores have encountered anomalously high concentrations likely resulting from in situ production of methane in the ice. With an ultra-high measurement resolution, such signals can be clearly identified and removed to obtain the true atmospheric history. The detailed records of methane variability and latitudinal gradients will be used to assess the nature of the multi-decadal scale signal and its relationship to past and future climatic change.
What will the student do?: 
You will start by developing a portable system to produce high resolution measurements of methane concentrations in ice cores using a new method that continuously measures the gas released from a narrow stick of melting ice core (3). You will measure ice cores from polar and mid-latitude locations at the British Antarctic Survey and/or in other laboratories by participating in measurement campaigns where liquid-phase chemistry is measured alongside the gas. Additionally, although this project is not dependent on the collection of new ice cores, we will endeavour to include you in future ice core drilling. In the second project phase, you will systematically screen your methane data for evidence of signal contamination using available chemistry data. Finally, you will use the methane records obtained to determine the latitudinal distribution of methane sources with the aid of numerical modelling. Depending on your results and interests, there will be opportunities to use a range of tools from simple box models to fully integrated atmospheric chemistry models. Results will be interpreted alongside available palaeoclimate data to explore climatic controls on methane variability.
1. Nisbet, E.G., Manning, M.R., Dlugokencky, E.J., Fisher, R.E., Lowry, D., Michel, S.E., Myhre, C.L., Platt, S.M., Allen, G., Bousquet, P., Brownlow, R., Cain, M., France, J.L., Hermansen, O., Hossaini, R., Jones, A.E., Levin, I., Manning, A.C., Myhre, G., Pyle, J.A., Vaughn, B.H., Warwick, N.J., White, J.W.C., 2019. Very Strong Atmospheric Methane Growth in the 4 Years 2014–2017: Implications for the Paris Agreement. Global Biogeochemical Cycles 33, 318–342.
2. 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.
3. Rhodes, R.H., Faïn, X., Stowasser, C., Blunier, T., Chappellaz, J., McConnell, J.R., Romanini, D., Mitchell, L.E., Brook, E.J., 2013. Continuous methane measurements from a late Holocene Greenland ice core: Atmospheric and in-situ signals. Earth and Planetary Science Letters 368, 9–19.
You can find out about applying for this project on the Department of Earth Sciences page.