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UCL Home  /  Geography  /  People  /  Academic Staff  /  David Thornalley

Dr David Thornalley

dt.jpgAssociate Professor

Rm 112, North-West Wing

Department of Geography
University College London
North-West Wing
Gower Street
London
WC1E 6BT

E-Mail: d.thornalley@ucl.ac.uk
Tel.: +44 (0)20 7679 0506

I am interested in understanding the causes, mechanisms and impacts of climate change on decadal to millennial timescales. I use a range of sedimentary and geochemical proxies in marine sediment cores, with a particular emphasis on reconstructing past changes in the circulation of the North Atlantic.

Employment

Senior Lecturer/Associate Professor, University College London (2017-present)

Lecturer, University College London (2013-2017)

Adjunct Scientist, Woods Hole Oceanographic Institution (2013-present)

Postdoctoral Research Scholar, Woods Hole Oceanographic Institution (2011-2013)

Postdoctoral Research Associate, Cardiff University (2008-2011)

 

Qualifications

PhD, University of Cambridge (2008)

MSci, MA, University of Cambridge (2004)

Professional Certificate in Teaching and Learning in Higher and Professional Education, Inst. of Education, London (2015)

 

Professional Service

Editor (topical), Climate of the Past

Associate Editor, Paleoceanography and Paleoclimatology

Member, International Evaluation Board for CHESS (Norwegian Research School on Changing Climates in the Coupled Earth System)

Deputy Director (Training lead) of the London NERC DTP

Deputy Chair of Phys. Geog. MSc programmes

 

2020

B. Langley, P. Halloran, A. Power, R. Rickaby, P. Chana, P. Diver, D. Thornalley & J. Love. The Hunt for Coccospheres: A New Method for Isolating and Analysing Coccospheres from Sediment. In revision; Scientific Reports.

Levke Caesar, Gerard McCarthy, David Thornalley and Stefan Rahmstorf. A millennium of AMOC changes. In revision, Nature Geoscience.

Peter Spooner, David Thornalley, Stuart Cunningham & J. Murray Roberts. Changing ocean state and its impact on natural capital (2020). 7 pp. Policy Brief for Scottish Government.

P. Spooner, D.J.R. Thornalley, D. Oppo, A. Fox, S. Radionovskaya, N. Rose, R. Mallett, E. Cooper, J.M. Roberts. Exceptional 20th century ocean circulation in the Northeast Atlantic (2020). Geophysical Research Letters. https://doi.org/10.1029/2020GL087577.

Brierley, C. M., Zhao, A., Harrison, S. P., Braconnot, P., Williams, C. J. R., Thornalley, D. J. R., Shi, X., Peterschmitt, J.-Y., Ohgaito, R., Kaufman, D. S., Kageyama, M., Hargreaves, J. C., Erb, M. P., Emile-Geay, J., D'Agostino, R., Chandan, D., Carré, M., Bartlein, P., Zheng, W., Zhang, Z., Zhang, Q., Yang, H., Volodin, E. M., Tomas, R. A., Routson, C., Peltier, W. R., Otto-Bliesner, B., Morozova, P. A., McKay, N. P., Lohmann, G., Legrande, A. N., Guo, C., Cao, J., Brady, E., Annan, J. D., and Abe-Ouchi, A.: Large-scale features and evaluation of the PMIP4-CMIP6 midHolocene simulations (2020). Clim. Past Discuss., https://doi.org/10.5194/cp-2019-168.

2019

F. Pöppelmeier, P. Blaser, M. Gutjahr, F. Süfke, D. J. R. Thornalley, J. Grützner, K. A. Jakob, J. M. Link, S. Szidat, J. Lippold. Influence of Ocean Circulation and Benthic Exchange on Deep Northwest Atlantic Nd Isotope Records During the Past 30,000 Years (2019). Geochemistry, Geophysics, Geosystems, https://doi.org/10.1029/2019GC008271

C. Waelbroeck et al., including D. Thornalley (2019). Consistently dated Atlantic sediment cores over the last 40 thousand years. Scientific Data. 6, 165, https://doi.org/10.1038/s41597-019-0173-8

S. Barker, G. Knorr, S. Conn, S. Lordsmith, D. Newman & D. Thornalley (2019). Early interglacial legacy of deglacial climate instability. Paleoceanography & Paleoclimatology, doi: 10.1029/2019PA003661

Yu, J., Menviel, L., Jin, Z.D., Thornalley, D.J.R., Foster, G.L., Rohling, E.J., McCave, I.N., McManus, J.F., Dai, Y., Ren, H., He, F., Zhang, F., Chen, P.J., Roberts, A.P. (2019). More efficient North Atlantic carbon pump during the Last Glacial Maximum. Nature Communications, 10, 2170, doi.org/10.1038/s41467-019-10028-z

2018

D.J.R. Thornalley, D.W. Oppo, P. Ortega, J.I. Robson, C.M. Brierley, R. Davis, I.R. Hall, P. Moffa-Sanchez, N.L. Rose, P.T. Spooner, I. Yashayaev & L.D. Keigwin (2018). Anomalously weak Labrador Sea convection and Atlantic overturning during the past 150 years. Nature, https://doi.org/10.1038/s41586-018-0007-4.

Spooner, P., Thornalley, D.J.R. & Ellis, P. (2018). Grain size constraints on glacial circulation in the southwest Atlantic. Paleoceanography & Paleoclimatology, 33, https://doi.org/10.1002/2017PA003232

2017

A.P. Hasenfratz, R. Schiebel, D.J.R. Thornalley, J. Schönfeld, S.L. Jaccard, A. Martínez-García, A. Holbourn, A.E. Jennings, W. Kuhnt, C.H. Lear, T.M. Marchitto, U. Quillmann, Y. Rosenthal, J. Yu,G.H. Haug. Mg/Ca-temperature calibration for the benthic foraminifera Melonis barleeanum and Melonis pompilioides (2017). Geochimica et Cosmochimica Acta, 217, 365-383. http://dx.doi.org/10.1016/j.gca.2017.08.038

I.N. McCave, D.J.R. Thornalley, I.R. Hall (2017). Relation of sortable silt grain size to deep-sea current speeds: Calibration of the ‘Mud Current Meter’. Deep Sea Research Part I, 127C, 1-12, doi: 10.1016/j.dsr.2017.07.003

P. Ortega, J. Robson, P. Moffa-Sanchez, D. Thornalley & D. Swingedouw (2017). A last millennium perspective on North Atlantic variability: exploiting synergies between models and proxy data. Past Global Changes Magazine, Volume 25, No. 1, 61-67, doi: 10.22498/pages.25.1.61

M.M. Ezat, T.L. Rasmussen, D.J.R. Thornalley, J. Olsen, L. Skinner, B. Hönisch, & J. Groeneveld (2017). Ventilation history of Nordic Seas overflows during the last (de)glacial period revealed by species-specific foraminiferal 14C dates. Paleoceanography, 32, 172–181, doi:10.1002/2016PA003053.

2016

J. Yu, L. Menviel, Z. Jin, D.J.R. Thornalley, S. Barker, G. Marino, E.J. Rohling, Y. Cai, F. Zhang, X. Wang, W.S. Broecker 2016. Deep Atlantic carbon sequestration and atmospheric CO2 decline during the last glaciation. Nature Geoscience doi:10.1038/NGEO2657.

Hoogakker, B., Thornalley, D.J.R., Barker, S. 2016. Millennial changes in North Atlantic oxygen concentrations. Biogeosciences, 13, 211-221, doi:10.5194/bg-13-211-2016.

Ninnemann, U.S., Thornalley, D.J.R. 2016. Recent natural variability of the Iceland Scotland Overflows on decadal to millennial timescales: Clues from the ooze. US Clivar Variations, 14 (3), 1-8.

2015

Blaschek, M., Renssen, H., Kissel, C. & Thornalley D.J.R. 2015. Holocene North Atlantic Overturning in an atmosphere-ocean-sea-ice model compared to proxy-based reconstructions. Paleoceanography, doi: 10.1002/2015PA002828.

Thornalley, D.J.R., Bauch, H.A., Gebbie, G., Guo, W., Zielger, M., Barker, S & Skinner, L. 2015. A warm and poorly ventilated deep Arctic Mediterranean during the last glacial period. Science, 349, 706-710.

P. Moffa-Sanchez, I. R. Hall, D.J.R. Thornalley, S. Barker, C. Stewart 2015. Changes in the strength of Nordic Seas Overflows over the past 3000 years. Quat. Sci. Rev. 123, 134-143.

Thornalley, D.J.R. 2015. Reconstructing Deglacial Circulation Changes in the Northern North Atlantic and Nordic Seas: Δ14C, δ13C, Temperature and δ18OSW Evidence. Nova Acta Leopoldina, NF 121, Nr. 408, 223-228.

Stephen Barker, James Chen, Xun Gong, Lukas Jonkers, Gregor Knorr, David Thornalley 2015. Icebergs were not the trigger for North Atlantic cold events. Nature, 520, 333-336.

Bakker, P., A. Govin, D.J.R. Thornalley, D. M. Roche, H. Renssen 2015. The evolution of deep-ocean flow speeds and δ13C under large changes in the Atlantic overturning circulation: Toward a more direct model-data comparison. Paleoceanography, 30, 95117.

2014

Moffa Sánchez, P., Born, A., Hall, I.R., Thornalley, D.J.R., Barker, S. 2014. Solar forcing of North Atlantic surface temperature and salinity over the past millennium. Nature Geoscience 7, 275-278.

Moffa Sánchez, P., Hall, I., Barker, S., Thornalley, D.J.R., Yashayaev I. 2014. Surface ocean changes in the Eastern Labrador Sea during the last millennium. Paleoceanography, 29, 160175.

2013

Griffiths, J., Barker, S., Hendry, K., Thornalley, D.J.R., van de Flierdt, T., Anderson, R. & Hall, I. 2013. Evidence of silicic acid leakage to the tropical Atlantic via Antarctic intermediate water during Marine Isotope Stage 4. Paleoceanography, doi:10.1002/palo.20030.

Thornalley, D.J.R., Blaschek, M., Davies, F.J., Praetorius, S., Oppo, D.W., McManus, J.F., Hall, I.R., Kleiven, H., Renssen., H. & McCave, I.N. 2013 Long-term variations in Iceland-Scotland overflow strength during the Holocene. Climate of the Past, 9, 1627-1656.

Yu, J., Thornalley, D.J.R., Rae, J., McCave, I.N., 2013. Calibration and application of B/Ca, Cd/Ca and d11B in Neogloboquadrina pachyderma (sinistral) to constrain CO2 uptake in the subpolar North Atlantic during the last deglaciation. Paleoceanography, 28, doi:10.1002/palo.20024.

Thornalley, D.J.R., Barker, S., Becker, J., Knorr, G. & Hall, I.R., 2013. Abrupt changes in ocean circulation during the onset of full glacial conditions. Paleoceanography, 28, doi: 10.1002/palo.20025.

2011

Thornalley, D.J.R., Barker, S., Broecker, W.S., Elderfield, H. & McCave, I.N., 2011. The deglacial evolution of North Atlantic deep convection. Science, 331, 202-205.

Hall, I.R., Evans, H.K. and Thornalley, D.J.R., 2011. Deep water flow speed and surface ocean changes in the subtropical North Atlantic during the last deglaciation. Global & Planetary Change doi:10.1016/j.gloplacha.2010.12.001

Thornalley, D.J.R., McCave, I.N. & Elderfield, H., 2011. Tephra in deglacial ocean sediments south of Iceland: Stratigraphy, geochemistry and oceanic reservoir ages.  Journal of Quaternary Science, doi: 10.1002/jqs.1442

2010

Thornalley, D.J.R., Elderfield, H. & McCave, I.N., 2010. Reconstructing deglacial North Atlantic surface hydrography and its link to the Atlantic overturning circulation. Global & Planetary Change, doi:10.1016/j.gloplacha.2010.06.003

Thornalley, D.J.R., Elderfield, H. & McCave, I.N., 2010. Intermediate and Deep Water Paleoceanography of the northern North Atlantic over the last 21,000 years. Paleoceanography, 25, PA1211, doi:10.1029/2009PA001833.

Thornalley, D.J.R., McCave, I.N. & Elderfield, H., 2010. Freshwater Input and Abrupt Deglacial Climate Change in the North Atlantic: Paleoceanography, 25, PA1201, doi:10.1029/2009PA001772.

2009

Thornalley, D.J.R., Elderfield H. & McCave, I.N., 2009. Holocene Oscillations in Temperature and Salinity of the Subpolar North Atlantic: Nature, 457, 711-714.

2005

McCave, I.N., Kiefer, T., Thornalley, D.J.R. & Elderfield, H., 2005. Deep Flow in the Madagascar-Mascarene Basin Over the Last 150,000 Years: Philosophical Transactions of the Royal Society of London A, 363, 81-99.

During the late Quaternary, the Earth’s climate system has undergone climate oscillations on a range of timescales, from multi-decadal processes to glacial-interglacial cycles occurring every ~100,000 years. Changes in ocean circulation played a significant role in these climate events by altering the global redistribution of heat, dissolved nutrients and carbon. My research focuses on constraining how the circulation of the ocean changed in the past and the mechanisms by which these changes affected the global climate system and marine ecosystems.

I use a wide range of tools including: faunal assemblage, isotope and elemental ratio (e.g., Mg/Ca, B/Ca, Cd/Ca) analysis of foraminifera to reconstruct water mass properties; geochemical proxies of circulation such as measurement of Pa/Th ratios, Nd isotopes and radiocarbon concentrations; examination of the detrital components of sediment such as ice-rafted detritus and geochemical analysis of tephra for improving stratigraphy; sediment grain size analysis (e.g. sortable silt analysis) to reconstruct relative changes in paleo-current strength; and fluxes and composition of organic matter to the seafloor, combined with benthic faunal assemblage to investigate marine ecosystem changes.

Selected grants

  • 2021 - 2025 Intra-interglacial variability: are warmer periods climatically more unstable? (VARING). (NERC. £784,021. PI: P.C. Tzedakis; Co-I: D. Thornalley; Res. Co-I: V. Margari)
  • 2019 - 2023 Integrated Assessment of Atlantic Marine Ecosystems in Space and Time (iAtlantic). (EU Horizon 2020, €10,600,000 consortium. Thornalley - Co-I, €140,000 for UCL)
  • 2019 - 2022 Beyond the instrumental record: Reconstructing Atlantic overturning over the past 7000 yrs (ReconAMOC). (NERC. £750,685. PI: D. Thornalley; Co-I: C. Brierley, S. Moreton; Res. Co-I: P. Spooner)
  • 2016 - 2020: ATLAS: A Trans-AtLantic Assessment and deep-water ecosystem-based Spatial management plan for Europe. (9m euro consortium from EU Horizon 2020; Deputy work-package leader and Co-I; 204,000 euros for UCL)
  • 2016 - 2019: Examining past abrupt climate change in the North Atlantic. (PI; Philip Leverhulme Prize. £100,000)
  • 2012 - 2015: Holocene reconstructions of Iceland-Scotland Overflow and the Deep Western Boundary Current. (Co-PI; $545,000 from NSF; including co-chief on 8 day cruise south of Iceland)
  • 2013 - 2015: North Atlantic deep water formation during the deglacial rise of atmospheric CO2. (PI; $22,500 from WHOI Institute of Ocean and Climate Change)
  • 2011 - 2013: The role of North Atlantic circulation during past abrupt climate change. (PI; $90,000 from WHOI Institute of Ocean and Climate Change for Postdoctoral Research Scholarship)
  • 2011 - 2012: A direct link between ocean circulation and abrupt climate change? (Researcher Co-I; £60,000 from UKIODP/NERC)

 

    Ongoing research projects

    The response of the Western Boundary Undercurrent to past abrupt climate change

    Deep water produced in the high latitude North Atlantic forms a deep western boundary current (locally termed the Western Boundary Undercurrent, WBUC) that flows southward, at depth, along the eastern margin of North America. The WBUC plays an important role in rapidly transmitting climate signals into the ocean interior and helping ventilate the world’s ocean. I am using grain size analysis to examine how the flow speed structure of the WBUC altered between warm and cold climate intervals throughout previous interglacial periods, during the last glacial period and the Holocene (Figure 1). This work is also coupled to isotope ratios and element ratios in benthic foraminifera to determine changes in circulation patterns.

    Figure 1. By measuring variations in the grain size of sediment in cores taken from the Northwest Atlantic, I am investigating how the flow speed structure of the Western Boundary Undercurrent (WBUC) altered under different climate states

    fig1.jpg

     

    Holocene and interglacial changes in the strength of the AMOC

    The formation of cold, dense water in the North Atlantic plays a critical role in the global thermohaline circulation, and the compensating inflow of Atlantic surface waters helps warm NW Europe. Using grain size data from cores taken around the Atlantic, as well as reconstruction of surface ocean temperature in the subpolar region, I am investigating the strength of the Atlantic thermohaline circulation and its deep components throughout the Holocene (~0-11,000 years ago), examining likely controls and effects and its link with broader climate variability. With collaborators from WHOI, we collected new cores on cruises in May 2014 and Aug 2019. These cores are being used to examine changes in circulation over the past 2000 years, focussing on if there exceptional changes during the Industrial era. This work forms part of an NSF project and our ongoing ReconAMOC project, which also involve analysis of cutting edge transient Holocene climate model simulation. Our new project - VARING - will extend this work to look at climate and AMOC variability during previous interglacials, to find out if warmer climates are more unstable.

    Deglacial changes in the circulation of the North Atlantic

    The termination of the last Ice Age was accompanied by abrupt changes in ocean circulation. The North Atlantic and Nordic Seas in particularly were subject to dramatic reorganisations that are thought to have had an impact on global climate evolution through this period. Yet the mechanisms behind these changes remain uncertain. I use elemental ratios in benthic foraminifera to constrain changes in the physical and chemical properties of the North Atlantic and Nordic Seas. I am also using benthic radiocarbon dating to help constrain the ventilation of this oceanographic region since the last glacial.

    Figure 2. A sediment core from south of Iceland. Ongoing work involves correlating volcanic ash layers (black layers) in the cores to similar ash layers found in Greenland ice cores to help determine lead-lag relationships between different climate archives. Measuring the elemental ratios in foraminifera (microscopic, single-celled organisms), found within the core, can also be used to reconstruct the past physical and chemical properties of the ocean and determine its role during past climate change.

    fig2.jpg

    Subpolar gyre dynamics and ecosystem change during the Holocene

    The strength of the North Atlantic’s subpolar gyre varies on annual to millennial timescales and it is likely involved in feedback mechanisms that impact atmospheric circulation and the overturning circulation of the ocean. I am investigating how the circulation of subpolar gyre changed on decadal timescales throughout the last 2,000 years, as well as investigating millennial scale changes throughout the Holocene. As part of the EU Atlas and iAtlantic projects (http://www.eu-atlas.org/) my research group is investigating the potential impact of recent Atlantic circulation changes on deep sea ecosystems and marine resources.

    In 2016, I was awarded a Philip Leverhulme Prize in Geography, which "recognizes the achievement of outstanding researchers whose work has already attracted international recognition and whose future career is exceptionally promising".

    My work focusses on understanding the role of the North Atlantic in abrupt climate change, and its impact on marine ecosystems. This work has revealed unexpected variability in the properties of both the surface and deep ocean, resulting in publications in Nature and Science, as well as wider public media attention, including coverage by The Guardian, Washington Post, TV coverage by Sky News, Channel 5 News and the BBC, and radio coverage by the BBC, NPR and others.

    My work has been cited in numerous national and international climate summary documents, including the 4th US National Climate Assessment, the Future Earth and the Earth League climate science update for the Katowice climate summit 2018, the IPCC Special Report on the Ocean and Cryosphere in a Changing Climate, as well as the upcoming IPCC Sixth Assessment Report.

    The research conducted by my group has contributed to a number of policy negotiations, highlighting the changes taking place in the North Atlantic. For example, the potential impact of a weakening AMOC on marine biodiversity was highlighted within the UK Government Sustainable Seas Inquiry (Environmental Audit Committee, 2019). Similarly, its potential to impact the resilience of deep-sea fauna to the impacts of deep-sea mining along the Mid-Atlantic Ridge was highlighted within an ATLAS submission to the International Seabed Authority, which provided comments on the draft Regulations on Exploitation of Mineral Resources in the Area (Boschen-Rose et al., 2018). The results of our work have been used to inform international policy, and have been presented at meetings including: the Second session of the intergovernmental conference (IGC) to develop an international legally binding instrument on the conservation and sustainable use of marine biological diversity of areas beyond national jurisdiction (ILBI for BBNJ)(March 2019, New York City); First Global Planning Meetings for the UN Decade of Ocean Science for Sustainable Development (May 2019, Copenhagen); Food and Agriculture Organizaton (FAO) ABNJ Deep Sea Meeting (May 2019, Rome); International Seabed Authority (ISA) workshop on the regional environmental management plan (REMP) for the area of the northern Mid-Atlantic Ridge (November 2019, Évora). We have also written an invited policy brief for the Scottish Government: "Changing ocean state and its impact on natural capital".

    The potential management impact of unusual circulation patterns has been highlighted by our recent research investigating variation in the North Atlantic subpolar gyre (Spooner et al., 2020, GRL). This work revealed that the changes in circulation experienced during the 20th century are unlike any conditions experienced in the past 10,000 years and align with a northward migration of Atlantic mackerel, which were first observed in Icelandic waters in the late 1800s and have been observed in high abundance since the early 2000s. This study shows that the hydrographic changes experienced in the subpolar gyre during the industrial era (and largely during the 20th century) are not part of normal fluctuations and are instead part of a long-term trend that is likely contributing to shifts in fish stock distributions (Spooner et al. 2020). This long-term trend emphasises the need to consider climate change impacts in the management of ocean resources and the potential need to re-evaluate fisheries policies (e.g., total allowable catch and quota allocations) for species that have entered new legislative areas.

    In 2015 I was awarded a UCL Student Choice Outstanding Teacher Award, and in 2019 shortlisted for Outstanding Research Supervision.

    I contribute to the following courses:

    Postgraduate courses

    • GEOG0118: Climate Dynamics  (MSc; co-taught with Chris Brierley)
    • GEOG0101: Ocean Circulation and Climate Change (MSc; convenor)
    • GEOG0122: Biological Indicators of Environmental Change (MSc; contributor)
    • GEOG0123: Climate Proxies (MSc; contributor)

    Undergraduate courses

    • GEOG00052: Palaeoclimate (3rd yr; co-taught with Jonathan Holmes)
    • GEOG0005: Earth: An integrated system (1st yr; convenor & contributor)

      2020-present: Zhiyi Jiang, Analysis of interglacial AMOC and climate change in PMIP and transient modelling experiments (Co-supervisor).

      2020-present: Daniel Parkes, Investigating the cause and structure of abrupt climate change events in MIS 11 (Co-supervisor).

      2019-present: Jack Wharton, Thermal structure of the Northwest Atlantic during the late Quaternary.

      2017-present: Alice Carter-Champion, Investigating the drivers and responses of climatic complexity during the Younger Dryas (Co-supervisor).

      2017-present: Paul Minton, Middle to late Miocene climate variability and biotic response: a high resolution record from Integrated Ocean Drilling Program (IODP) (Co-supervisor).

      2013-2019: Rehemat Bhatia, Geochemical signals in greenhouse and icehouse planktonic foraminifera (Co-supervisor).

      If you are interested in taking up a PhD place at UCL and working with me, please feel free to contact me about possible projects or check out the London NERC-DTP website