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Signals of the Ice Age in the tropics - new records from the Uruguayan Margin

Dr Tracy Aze (SEE), Jason Harvey (SEE), Ruza Ivanovic (SEE) and Robert Newton (SEE)

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The Last Glacial Maximum (LGM) ~26-19 thousand years ago was the most recent glacial period on Earth and was typified by extensive northern hemisphere glaciation, average global temperatures around 4 °C cooler than today and global sea levels were 130 m lower than the present. As climate warmed towards the present day and the vast northern ice sheets shrank, large volumes of meltwater flooded to the coasts, raising sea level and disrupting global-scale ocean circulation, and rapid changes in surface topography reorganized patterns of atmospheric circulation. Known as the last deglaciation, this period was an exciting time of abrupt changes in surface climate (including warming and cooling events) and the oceans.

Thus, the Last Glacial Maximum and subsequent deglaciation is the focus of much current research as we attempt to reach a better understanding of how the climate system responds to rapid climate fluctuations and better predict future climate change. This is principally achieved via improving and refining models based on primary data and knowledge of climate feedbacks and processes. The most recent assessment report from the Intergovernmental Panel on Climate Change (IPPC AR5) has stated that a number of issues remain regarding our understanding of the Last Glacial Maximum; namely the mismatch between proxy data and models regarding temperature estimates, the uncertainty surrounding the magnitude of tropical sea surface cooling, and the role of seasonal productivity and response of proxy-hosting plankton to variations in water column temperature and vertical stratification.

This project will focus upon direct sampling and analysis of cores donated by BG Group that have been collected from the Uruguayan Margin. The student will perform a number of geochemical and micropalaeontological investigations upon material spanning the Last Glacial Maximum and subsequent deglaciation. Specifically the student will:

  1. Produce new tropical sea surface and bottom water temperatures estimates for the S.W. Atlantic Ocean using carbon and oxygen isotope and Mg/analysis of foraminifer shells.

  2. Produce new records of the changing nature of surface and deep oceanic water masses using stable isotope, eNd and trace metal analysis of foraminifer shells.

  3. Produce new records of the influence of seasonality on productivity and depth migration of planktonic foraminifera throughout the LGM and deglaciation using assemblage composition and carbon and oxygen stable isotope and trace metal analyses.

  4. The project will make use of the state-of-the-art laboratory facilities at the University of Leeds, both in the Micropalaeontology Laboratory (sediment processing and microfossil imaging) and the Cohen Geochemistry Laboratories (C and O isotopes, eNd and Mg/Ca and other trace metal analyses on benthic and planktonic foraminifera and bulk sediments).

Impact of the Research and Publications

The project is designed to test a number of clear hypotheses, with each work package designed towards the publication of a paper, which have clear potential for impact on the international scientific community

An Excellent Training and Research Environment

This interdisciplinary project will provide the successful PhD candidate with highly valued and sought-after tools for investigating palaeoceanography, past climates and species interactions with their environments, such as: analytical geochemistry, morphometrics and taxonomy and environmental modelling. This will equip the student with the necessary expertise to become the next generation of palaeontological and climate scientist, ready to carry out their own programme of innovative scientific research. The student will benefit from working within and collaborating with dynamic scientists within the multidisciplinary Palaeo@Leeds group (e.g. Gregoire, Haywood, Little, Wignall), and the Cohen Geochemistry Group (e.g. Mearz, Newton, Peacock, Poulton). There will be opportunities to present results at major, international conferences, e.g. AGU (San Francisco), EGU (Vienna), GSA, PalAss, and attend residential summer-schools (e.g. in Italy, USA, UK) and in-house workshops and courses.

Entry requirements

A good first degree (1 or high 2i), or a good Master’s degree in geological or environmental sciences with a focus towards palaeontology or palaeoceanography, experience in micropalaeontology and programming (e.g. R, Python) is an advantage.

Further Reading

Annan, J. D. and Hargreaves, J. C. 2013. A new global reconstruction of temperature changes at the Last Glacial Maximum. Climates of the Past. 9, 367-376.

Clark, P. U., Dyke, A.S., Shakun, J. D., Carlson, A. E., CLark, J., Wholfarth, B., Mitrovica, J.X., Hostetler, S. W. and McCabe, A. M. 2009. The Last Glacial Maximum. Science. 325, 710-714.

Harvey, J. and Baxter, E. F. 2009. An improved method for TIMS high precision neodymium isotope analysis of very small aquilots (1-10 ng). Chemical Geology. 258, 251-257.

Ivanovic, R. F., Gregoire, L. J., Kageyama, M., Roche, D. M., Valdes, P. J., Burke, A., Drummond, R., Peltier, W. R., and Tarasov, L. 2016. Transient climate simulations of the deglaciation 21–9 thousand years before present (version 1) – PMIP4 Core experiment design and boundary conditions. Geoscience Model Development. 9, 2563-2587.

Masson-Delmotte, V., M. Schulz, A. Abe-Ouchi, J. Beer, A. Ganopolski, J.F. González Rouco, E. Jansen, K. Lambeck, J. Luterbacher, T. Naish, T. Osborn, B. Otto-Bliesner, T. Quinn, R. Ramesh, M. Rojas, X. Shao and A. Timmermann, 2013: Information from Paleoclimate Archives. In: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Stocker, T.F., D. Qin, G.-K. Plattner, M. Tignor, S.K. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex and P.M. Midgley (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.



Figure 1. Agumented  Masson-Delmotte et al. (2013). “Changes in surface temperature for the Last Interglacial (LIG) as reconstructed from data and simulated by an ensemble of climate model experiments in response to orbital and well-mixed greenhouse gas (WMGHG) forcings. (a) Proxy data syntheses of annual surface temperature anomalies as published by Turney and Jones (2010) and McKay et al. (2011). McKay et al., (2011) calculated an annual anomaly for each record as the average sea surface temperature (SST) of the 5-kyr period centred on the warmest temperature between 135 ka and 118 ka and then subtracting the average SST of the late Holocene (last 5 kyr). Turney and Jones (2010) calculated the annual temperature anomalies relativeto 1961–1990 by averaging the LIG temperature estimates across the isotopic plateau in the marine and ice records and the period of maximum warmth in the terrestrial records (assuming globally synchronous terrestrial warmth). (b) Multi-model average of annual surface air temperature anomalies simulated for the LIG computed with respect to preindustrial. The results for the LIG are obtained from 16 simulations for 128 to 125 ka conducted by 13 modelling groups (Lunt et al., 2013).”

The red box in (b) highlights the lack of data for the LGM in the South West Atlantic Ocean.

Figure 2. A Google Earth image of the Ururguayan Coast. Left inset is a map showing the location of the 200 gravity cores that have been donated by BG Group. Right inset is a diagramtic representation of the different water masses that currently affect this region against depth. NADW= North Atlantic Deep Water, AIW = Antarctic Intermediate Water, UCDW = Upper Circumpolar Deep Water. The project will use geochemical tools such as carbon and oxygen isotopes and eNd to investigate the behaviour of the various different water masses during the LGM and deglaciation.

Related undergraduate subjects:

  • Chemistry
  • Earth science
  • Geological science
  • Micropalaeontology
  • Oceanography
  • Palaeontology