The most profound effects of anthropogenic climate change on the UK are driven by oceanic circulation changes triggered by melting of the Greenland Ice Sheet (GIS). Understanding GIS behaviour through geologic time provides crucial information on how it controls key climate tipping points in the North Atlantic.
The late Pliocene (3.4-2.4 Ma) is of particular interest to understanding these tipping points. This interval covers the warm mid-Piacenzian Warm Period (mPWP), used by the IPCC as an analogue for a future warm climate, to the initiation of widespread glaciations at the Pliocene-Pleistocene transition.
Much research has concerned changes to global ocean circulation during this interval, but the Nordic seas themselves remain understudied. The vast bulk of available records in this interval measured Ice Rafted Debris (IRD): evidence of past icebergs flowing from continental Greenland. However, the influence of the ice sheet on the ocean goes beyond IRD, and can be measured more directly from the characteristics of the water itself.
We propose to use organic biomarkers and foraminifera to reconstruct a history of the Nordic Seas over this critical interval. Recent data has shown wide variations in SST across the region, including a mismatch between different methods of oceanic temperature reconstructions within the Irminger Sea during the mPWP that shows the influence of multiple current systems affecting the Site. Understanding the strength and characteristics of the varying network of currents and how they covary with the nearby GIS will constrain future behaviour of the entire North Atlantic current system into the future.
This project aims to reconstruct the behaviour of the Nordic Sea at multiple Sites through the late Pliocene, in order to determine how its characteristics affect the wider Atlantic current system. Organic proxies allow for reconstruction of many different aspects of the overlying ocean within a single sample, allowing for a comprehensive reconstruction of its behaviour: key targets include sea surface and intermediate water temperature, presence of sea ice, and freshwater input from the continent (Figure 1).
Figure 1: Biomarker contribution to sediment cores close to the Greenland Ice Sheet: each group of biomarkers preserves information on distinct oceanographic and biological processes that can then be reconstructed.
This project is not suitable for CASE funding
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The student will generate multi-proxy high temporal resolution climate records from several cores located around the Nordic Seas drilled by the International Ocean Discovery Program and/or predecessor projects (IODP/ODP/DSDP). Following a literature review in their first year, the PhD researcher will generate an organic and inorganic geochemical proxy record, including alkenone UK’37 and % C37:4, TEX86 and BIT index, IP25, planktic foram Mg/Ca, benthic foram δ18O and δ2H of alkenones and fatty acids. With the exception of the δ2H, all analytical measurements will be performed at the Open University by the student. We have several sites in mind for sampling, but welcome input from the student to refine the choice of sampling location and timescale to suit their research interests.
DRs will be awarded CENTA Training Credits (CTCs) for participation in CENTA-provided and ‘free choice’ external training. One CTC can be earned per 3 hours training, and DRs must accrue 100 CTCs across the three and a half years of their PhD.
The student will be trained in advanced organic geochemistry techniques including organic clean lab extractions, column chromatography and solvent handing techniques. Training will be provided in analysis using hyphenated techniques (GC-FID, GC-MS, LC-MS) in the state-of-the-art laboratories at the OU. The student will acquire significant skills in organic biomarker analysis, identification and interpretation. Further training will include:
Not applicable.
Year 1: Literature review, training in laboratory techniques with supervisors, wet lab extraction and purification of samples, age model refinement, lab analyses of pilot data (GC-FID).
Year 2: Analytical lab: GC-FID, GC-MS, HPLC-MS. Preparation of samples for δ2H analysis. Data analysis of temperature and sea ice biomarkers. Prepare first manuscript. Present preliminary data at UK-based conference (e.g. British Organic Geochemistry Society).
Year 3: Analysis of δ2H (freshwater input). Data interpretation. Present data at major international conference (e.g. International Congress on Palaeoceanography, St Andrews, 2028). Writing up thesis and subsequent manuscripts.
Journal:
Clotten, C. et al. (2018) ‘Seasonal sea ice cover during the warm Pliocene: Evidence from the Iceland Sea (ODP Site 907)’, Earth and Planetary Science Letters, 481, pp. 61–72. Available at: https://doi.org/10.1016/j.epsl.2017.10.011.
McClymont, E.L. et al. (2023) ‘Climate Evolution Through the Onset and Intensification of Northern Hemisphere Glaciation’, Reviews of Geophysics, 61(3), p. e2022RG000793. Available at: https://doi.org/10.1029/2022RG000793.
Naafs, B.D.A.A. et al. (2020) ‘Repeated near‐collapse of the Pliocene sea surface temperature gradient in the North Atlantic’, Paleoceanography and Paleoclimatology, 35(5). Available at: https://doi.org/10.1029/2020PA003905.
Sarnthein, M. et al. (2009) ‘Mid-Pliocene shifts in ocean overturning circulation and the onset of Quaternary-style climates’, Climate of the Past. Available at: https://doi.org/10.5194/cp-5-269-2009
St John, K.E.K. and Krissek, L.A. (2002) ‘The late Miocene to Pleistocene ice‐rafting history of southeast Greenland’, Boreas, 31(1), pp. 28–35. Available at: https://doi.org/10.1111/j.1502-3885.2002.tb01053.x.
Knies, J. et al. (2014) ‘The emergence of modern sea ice cover in the Arctic Ocean’, Nature Communications, 5(1), p. 5608. Available at: https://doi.org/10.1038/ncomms6608.
Students should have a background in Earth science, geography, environmental science, chemistry or similar, and an enthusiasm for palaeoclimate and geochemistry. Experience of labwork and knowledge of organic geochemistry is highly desirable. The student will join a well-established team researching paleoenvironmental change at the Open University. If you would like to apply or require further information please contact [email protected].
To apply to this project:
Applications must be submitted by 23:59 GMT on Wednesday 7th January 2026.