Global atmospheric concentrations of carbon dioxide are rising at a rate unprecedented in the history of the Earth as a result of human activity. Today’s value of ~400 ppmv is higher than it has been for ~25 million years.
Our ability to predict the effects of increased atmospheric carbon dioxide levels critically depends on understanding the interactions between the physical, chemical and biological processes that occur on our planet. Increased concentrations of atmospheric carbon dioxide cause a direct warming of the Earth’s surface.
This warming, however, can significantly alter the rates at which carbon dioxide is itself transferred between the Earth’s chemical and biological carbon reservoirs. Changes in these rates may either enhance or reduce the current rise in atmospheric carbon dioxide concentrations, creating the potential for feedbacks within the climate system that are still poorly constrained.
Our understanding of these feedbacks is based upon the historical and geological record of past climate change. Geological data of ancient climate conditions has revealed numerous complex and often rapid changes in the Earth’s climate.
This research project focuses on the causes of the most significant climate transition of the past 65 million years, when a continent-wide ice cap first appeared on Antarctica, 34 million years ago.
The rapid growth of the Antarctic ice-sheet appears to have been triggered when a long-term decline in atmospheric carbon dioxide concentrations crossed a critical threshold of ~750ppmv. At this point various positive feedback mechanisms, such as increased marine primary productivity, caused a rapid cooling into a deep glacial state.
We are seeking to understand the feedbacks between climatic cooling, Antarctic glaciation and marine primary productivity across this climate transition. In particular, this project uses the tiny fossil remains of single-celled marine algae called coccolithophores.
These algae live in the surface waters of the ocean and are responsible for a large portion of the photosynthesis, or “primary production”, of the world’s oceans. As a result they play a critical role in the uptake of carbon dioxide by the surface ocean from the atmosphere and its conversion into inorganic (calcium carbonate) and organic carbon.
They form the base of the marine food chain and variations in their productivity have large impacts on the chemistry of the oceans. By studying the abundance, distribution, evolution and chemistry of fossil coccolithophores, we aim to quantify changes in the biological productivity of the ocean and its role in removing carbon dioxide from the atmosphere and climate cooling.
Understanding the relative importance of changes in marine primary productivity in Earth’s history will help us to predict its future role in reducing or accelerating anthropogenic climatic change.
Members of staff involved
Tom Dunkley Jones
- Sufiah Sulaiman
- Katy Prentice (PhD student Imperial College; lead supervisor Tom Dunkley Jones)
- Cherry Newsam (PhD student University College London; co-supervisor Tom Dunkley Jones)
2013 University of Birmingham – University of Nottingham Strategic Collaboration Fund (£40k), Joint with Dr George Swann, UoN Geography; Antarctic ice-sheet controls on tropical Pacific nutrient cycling.
2013 ECORD Research Grant: The role of ocean productivity in carbon cycle changes through the Eocene/Oligocene Transition
2012-2013 Royal Society Small Grant (£15k): Paleogene marine calcareous phytoplankton: ecological dynamics through rapid climate events and long-term macroevolution;
2010-2013 Royal Society Dorothy Hodgkin Fellowship (£395k);
2012 NERC Ion Microprobe Facility Grant:IMF743/1012 Trace metal constraints on coccolithophore calcification mechanisms;
2011 NERC Ion Microprobe Facility Grant: IMF420/1010 Surface ocean productivity through the Eocene/Oligocene transition using the Sr/Ca composition of coccolith calcite.
Pälike, H., et al. 2012. A Cenozoic record of the equatorial Pacific carbonate compensation depth, Nature 488: 609-615, doi:10.1038/nature11360
Bown, P.R. and Dunkley Jones, T. 2012. Calcareous nannofossils from the Paleogene equatorial Pacific (IODP Expedition 320 Sites U1331-1334). J. Nannoplankton Res. 32(2):3-51.
Westerhold, T., Röhl, U., Wilkens, R., Pälike, H., Lyle, M., Dunkley Jones, T., Bown, P., Moore, T., Kamikuri, S., Acton, G., Ohneiser, C., Yamamoto, Y., Richter, C., Fitch, P., Scher, H., Liebrand, D. and the Expedition 320/321 Scientists. 2012. Revised composite depth scales and integration of IODP Sites U1331–U1334 and ODP Sites 1218–1220, Proceedings of the Integrated Ocean Drilling Program, 320/321, doi: 10.2204/iodp.proc.320321.201.2012.
Dunkley Jones, T., P. R. Bown, and P. N. Pearson. 2009. Exceptionally well preserved upper Eocene to lower Oligocene calcareous nannofossils (Prymnesiophyceae) from the Pande Formation (Kilwa Group), Tanzania, Journal of Systematic Palaeontology 7(4):359-411, doi:10.1017/S1477201909990010.
Dunkley Jones, T., Bown, P.R., Pearson, P.N., Wade, B.S., Coxall, H.K., and Lear, C.H. 2008. Major shifts in calcareous phytoplankton assemblages through the Eocene-Oligocene transition of Tanzania and their implications for low-latitude primary production, Paleoceanography 23, PA4204, doi:10.1029/2008PA001640.
Pearson, P. N. McMillan, I. K., Wade, B. S., Dunkley Jones, T., Coxall, H. K., Bown, P. R. and Lear, C. H. 2008. Extinction and environmental change across the Eocene/Oligocene boundary in Tanzania. Geology 36:179-182, doi:10.1130/G24308A.
Bown, P. R, Dunkley Jones, T., Lees, J.A., Pearson, P.N., Randell, R., Coxall, H.K., Mizzi, J., Nicholas, C., Karega, A., Singano, J., Wade, B.S. 2008. A calcareous microfossil Konservat-Lagerstätte from the Paleogene Kilwa Group of coastal Tanzania. GSA Bulletin 120:3-12, doi:10.1130/B26261.1.
Key periods of data collection/fieldwork activity
Integrated Ocean Drilling Program (IODP) Expedition 320: Pacific Equatorial Age Transect. 2009. Shipboard scientist Tom Dunkley Jones
Tanzanian Drilling Project (2004-5). Expedition Scientist Tom Dunkley Jones
Opportunities (e.g. PhD proposals)
Tanzania Onshore Paleogene Integrated Coring (TOPIC); International Continental Scientific Drilling Program proposal. Co-proponent Tom Dunkley Jones. Proposal workshop September 2014, Dar-es-Salaam.