Funding Source: CENTA DTP
Proposed start date: 27th September 2021
Project Highlights:
• Utilisation of a novel palaeoenvironmental archive for dryland regions - the communal latrines of the rock hyrax
• Application of analytical and numerical methods to provide new insights into drivers of climatic variability across centennial to multi-millennial timescales.
• Fieldwork in southern Africa supported by an established international research team focused on African palaeoclimates
Overview:
Southern Africa lies within a critical transitional zone of the global oceanic and atmospheric circulatory systems. Its response to future global climatic change and to palaeoclimatic changes (e.g. over Pleistocene glacial-interglacial cycles) has therefore attracted international scientific interest. The region is however challenging to work in, largely because its semi-arid climate does not favour the preservation of palaeoenvironmental and palaeological archives. In recent years a novel approach to address this using the stratified communal latrines of the Rock Hyrax (Chase et al., 2012; Figure 1) - as led by the supervisory team - has resulted in the creation of remarkable high-resolution records of long-term climate change. Highlights include the recent publication of a composite 50,000 year record for the whole Namib Desert (Chase et al., 2019a).
As more hyrax midden records have been developed, one of the most striking and challenging findings is the apparent spatial variability in Pleistocene-Holocene climatic trends, particularly along the southern and western margins of South Africa, close to the boundaries of the summer (tropical) /winter (temperate) rainfall zones (Figure 1; Chase and Quick, 2017; Chase et al., 2019b). This led us to hypothesise that spatial patterns in climate, particularly at millennial scales, were/are driven by complex interactions between the tropical and temperate components of the regional circulation. Understanding how these patterns manifest in space and time will provide both key insights into the functioning of the regional climate system, and a greater understanding of likely regional manifestations of hydrological change under future warming scenarios.
The aim of this PhD therefore is to interrogate this spatial-temporal patterning further, in terms of: 1) enhancing the spatial resolution/sampling density of our archives to validate and refine knowledge of (palaeo)hydroclimatic gradients; 2) utilising additional proxies (leaf wax D) to unpick the causes of arid/humid trends (e.g. water sources); 3) synthesising these new site/proxies with a suite of formal time-series analyses; and 4) considering these records in terms of mechanistic synoptic scale climatic systems (see Chase et al., 2017). From this, the PhD aims to provide detailed new insights into long-term interactions of Southern Hemisphere tropical-temperate climatic systems.
Methodology:
To address these questions, this project will develop several new hyrax midden records, sampling new sites recently identified and applying a multi-isotope analysis approach. The project therefore contains both field (South Africa) and laboratory stages. Analyses will be carried out in the University of Leicester Stable Isotope laboratory and will include stable nitrogen and carbon isotope analyses (insights into aridity and vegetation response, respectively), in conjunction with compound-specific analysis of leaf wax n-alkanes to obtain deuterium isotope records. The latter is a key step that will link these archives to palaeo-rainfall amounts and/or rainfall water sources, potentially allowing us to untangle the synoptic drivers of this apparent spatial-temporal climatic variation. To this end, new data will be integrated with our existing published and unpublished records, also requiring the student to develop and/or apply numerical methods for spatial-temporal analyses of the climatic trends, utilising for example, various time-series analysis methods (e.g. wavelet analysis).
Training and skills:
You will attain a high level of competence in cutting-edge analytical techniques, including isotope ratio mass spectrometry, lipid injection gas chromatography mass spectrometry (GC/MS) analysis and compound-specific stable isotope analysis of plant biomarkers. You will be trained in mass spectrometry and mass spectra interpretation. To complete the palaeoclimatic reconstructions you will work with multi-proxy data sets and create high-resolution age-depth models using radiocarbon methods and (e.g.) Bayesian modelling approaches. You will also be trained in the synthesis of palaeoclimatic data and particularly, methods of time series analysis of climate data.
Entry requirements:
Applicants are required to hold/expect to obtain a UK Bachelor Degree 2:1 or better in a relevant subject.
The University of Leicester English language requirements apply https://le.ac.uk/study/research-degrees/entry-reqs/eng-lang-reqs
To apply refer to https://le.ac.uk/study/research-degrees/funded-opportunities/centa-phd-studentships
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