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Cambridge NERC Doctoral Training Partnerships

Graduate Research Opportunities
 

Lead Supervisor: Louise Sime, British Antarctic Survey

Co-Supervisor: Francesco Muschitiello, Geography and Robin Smith, University of Reading

Brief summary: 
The concept of Tipping Points largely defines the current climate emergency. In this project you will use the current state-of-the-art UK climate model to investigate when Arctic sea ice tipping points last occurred.
Importance of the area of research concerned: 
The concept of Tipping Points, critical thresholds in our climate system, helps to define the current climate emergency and strengthens calls for urgent climate action. One of the most important and sensitive tipping elements is sea ice, illustrated most clearly by the recent loss of sea ice in the Arctic. The international community has identified a clear need for a better understanding of the non-linear behaviour of sea ice in the climate system, alongside its ocean and atmosphere feedbacks. Studying previous warm periods in Earth’s history can tell us how the climate system may behave in the future. Whilst previous simulations failed to capture abrupt Arctic sea-ice loss, Dr Sime’s group recently demonstrated that the latest version of the UK UKESM model accurately simulates Arctic sea ice loss during past warm climates. This is because of improved model physics, particularly a sophisticated sea-ice melt-pond scheme which allows the model to simulate a realistic loss of Arctic sea ice in summer during the Last Interglacial. Having accurate model sea ice physics is crucial to understanding how and when the Arctic will be become ice free in future (Guarino et al. 2020).
Project summary : 
In this project the student will use the current state-of-the-art UKESM model to investigate potential Arctic tipping points during past periods of rapid sea ice change. We know that the last glacial period was marked by several abrupt shifts in ocean circulation and global climate, known as Dansgaard-Oeschger (DO) events. DO events were accompanied by temperature swings of 10-15˚C in northern high latitudes, which were likely prompted by rapid changes in Arctic and North Atlantic sea-ice cover (Sadatzki and Muschitiello et al., 2019). An accurate understanding of the phasing and physical mechanisms linking DO events and sea-ice variability requires data from the ice core and palaeoceanographic records (Sime et al., 2019) to be linked with detailed modelling of the climate system.
What will the student do?: 
The student will use UKESM (Sellar et al., 2019), the current state-of-the-art UK climate model to simulate Dansgaard-Oeschger events. UKESM is a highly detailed model with interactively coupled components for the atmosphere, land, ocean and ice. Using the unique capabilities of this model, the student will investigate the role that sea ice plays in DO events, the implications for tipping points in our current climate, and potentially unite the key marine and ice core sources of evidence for past sea ice loss. The student will: 1. Configure and run UKESM simulations of time periods when Dansgaard-Oeschger events occur. 2. Compile ice core and marine records of sea ice change for these periods to compare with our climate simulations. 3. Run sensitivity simulation to ascertain the importance of role of melt ponds, snow-ice albedo changes, and other radiative feedbacks for the abrupt loss of the Arctic sea ice. 4. Create synthetic cores using millennial-scale simulations with UKESM-Fast equipped with water tracers (https://www.bas.ac.uk/project/water-isotopes-in-ukesm2/) to investigate how sea ice change is recorded in polar marine and ice cores.
References - references should provide further reading about the project: 
Guarino, M., Sime, L.C., Schroeder, D. et al. Sea-ice-free Arctic during the Last Interglacial supports fast future loss. Nat. Clim. Chang. (2020). https://doi.org/10.1038/s41558-020-08
Sadatzki, H., Dokken, T.M., Berben, S.M.P., Muschitiello, F., Stein, R., Fahl, K., Menviel, L., Timmermann, A. and Jansen, E., 2019. Sea ice variability in the southern Norwegian Sea during glacial Dansgaard-Oeschger climate cycles. Science Advances, v. 5, p.eaau6174-. doi:10.1126/sciadv.aau6174.
Sime, Louise , Hopcroft, Peter O., Rhodes, Rachael H.. (2019) Impact of abrupt sea ice loss on Greenland water isotopes during the last glacial period. Proceedings of the National Academy of Sciences of the United States of America, 116. 4099-4104. 10.1073/pnas.1807261116
Applying
You can find out about applying for this project on the British Antarctic Survey (BAS) page.
Louise Sime
British Antarctic Survey Graduate Administrator