IAP-25-016

Antarctic sea ice, circulation and ice sheet interactions in the Southeastern Weddell Sea

Antarctic sea ice is an important component of global climate, due to its impact on a range of climate feedbacks and the unique ecosystems it supports. For example, it impacts albedo (the reflection of solar radiation), the exchange of gases between the ocean and atmosphere (including CO2), and the formation of deep water which feeds the global ocean conveyor. The last decade has seen dramatic decreases in sea-ice extent, raising concerns that sea ice loss may be accelerating (Abram et al., 2025). Future projections remain uncertain, due to current simulations not fully replicating observational data (Meredith et al., 2019). Marine sediments provide records of climate change extending over tens of thousands of years, which set the observational record into context but also allow us to test climate system responses to a wider range of forcings. For example, the Last Glacial Maximum ~20,000 years ago had low CO2 and an extensive Antarctic ice sheet, followed by a warming transition into the Holocene interglacial by ~11,000 years ago).

This project will use marine sediments recovered from the eastern Weddell Sea, a region critical to deep water export to the worlds oceans. Sediments held by the British Antarctic Survey will be used to
(1) generate a dated history of sea ice and ocean temperature changes from the Last Glacial Maximum to present;
(2) generate a record of marine productivity changes over the same time interval;
(3) explore the controls over marine productivity changes, which could include fertilisation by dust or icebergs, or the opening of polynyas within the sea-ice environment.

The resulting detailed records of physical and biological changes in the eastern Weddell Sea will provide an opportunity to relate regional sea ice and circulation change to global and local forcings across a range of timescales, ultimately enabling better constraints for important processes which influence future climate simulations.

This project will explore the environmental and climatic history recorded in the marine sediment core by drawing on a complementary suite of techniques including sedimentology, XRF scanning, marine microfossils, lipid biomarkers and radiocarbon dating. These methods have been successfully applied to address similar objectives elsewhere in Antarctica (e.g. Ashley et al., 2021; Khoo et al., 2025). For example, the sediments record changes in biological productivity, dust transport, and ice-rafted debris via sedimentology, XRF scanning and lipid biomarker analyses. The nature of the sea ice (e.g. year-round or seasonal) can be determined using diatom microfossils, foraminifera microfossils and lipid biomarkers (e.g. Khoo et al., 2025; Ashley et al., 2021). Preliminary analysis by the supervisory team confirms that the cores provide information extending from the LGM to the present.

Within the broad framework of the project outlined here, the student will have the opportunity to shape the project depending upon the emerging results and student interests, in discussion with the supervisory team. For example, rapid transitions or intervals of interest could be examined at higher time resolution, or additional techniques could be used to answer new questions raised by the results. Training will be provided by the supervisory team in all aspects of the project, as outlined below.

Year 1

Literature Review and Research Design. Begin analysis on marine sediment core (sedimentology, analysis of XRF core scanning data) including a visit to British Antarctic Survey where the cores are housed. Identify training needs for practical work and skills development, receive training in laboratory methods from the supervisory team. Complete pilot analyses on a sub-set of samples to identify whether any method adjustments are required (e.g. to ensure recovery of target microfossils and biomarkers).

Year 2

Identify additional dating requirements and submit samples for analysis. Prepare samples for microfossil and biomarker analysis (e.g. making slides, completing lipid extractions), analyse and compile the results. Present initial results at a conference (e.g. Quaternary Research Association Postgraduate Symposium, UK Antarctic Science meeting) and incorporate feedback into interpretations. Draft first Results & Discussion chapter, with an aim to submit for publication.

Year 3

Complete all laboratory analyses; write second and third discussion chapters with an aim for publication, and develop thesis structure and plan for submission. Present results at an international conference (e.g. SCAR, AGU, EGU).

Year 3.5

Complete writing of research papers / chapters and submit thesis.

The supervisory team covers the breadth of methods to be applied in this project, and will provide bespoke and hands-on training in all aspects. Transferable skills (e.g. thesis writing, presentation skills) will be developed through formal training events offered by IAPETUS as well as through Durham’s award-winning Career and Research Development group. Based at Durham University, the student will be a member of the Sea Level, Ice and Climate Research Cluster in the Department of Geography (https://www.dur.ac.uk/geography/slic/) which hosts regular seminars and training events. The student will also be supported to attend international training opportunities (e.g. the Urbino Summer School in Palaeoclimatology) and appropriate national and international conferences, as well as visits to supervisors and their research groups at the Lyell Centre (Heriot-Watt University) and British Antarctic Survey.