Prof. Paul A. Wilson, Prof. Heiko Palike
Rationale
If man-made CO2 emissions follow projected rates then, by the end of this century, atmospheric concentrations of this greenhouse gas will be higher than at any time since the Eocene ‘greenhouse’ when Earth was much warmer than today featuring, for example, a genuinely green Greenland. New evidence from the Pacific Ocean reveals pronounced instability in ocean acidity during the Eocene ‘greenhouse’ relative to the Oligo-Neogene ‘icehouse’ as indicated by dramatic changes in the depth of preservation of CaCO3 in sea floor sediments (the calcite compensation depth, CCD). Yet big CCD changes make it impossible to construct continuous climate records from calcareous microfossils in these Eocene Pacific Ocean sediments so our understanding of the links between changes in ocean acidity and global climate is limited. One way to overcome this problem is to work on correlative strata in the Atlantic Ocean where deep ocean sediments are richer in CaCO3 than their Pacific counterparts. This project will take advantage of a depth transect of sites to be drilled along the Newfoundland Ridge for this purpose by Integrated Ocean Drilling Program Expedition 342: http://iodp.tamu.edu/scienceops/expeditions/newfoundland_sediment_drifts.html You will have the opportunity to tackle a number of fundamental questions that remain subjects of vigorous debate. How stable was the Eocene greenhouse climate state? How did the acidity of the Eocene oceans change in association with these shifts in global climate? When and why did Earth shift to its present climate state with large ice sheets in both hemispheres? How stable were these high-CO2 ice sheets? Were these climate shifts driven by short-term carbon cycle perturbations or were they threshold responses to slow forcing that, in turn, triggered feedback systems in the carbon cycle?
Methodology
Opportunities exist for the student to participate in ocean-going research cruises. In the laboratory, modern micropaleontological techniques will be combined with isotopic and geochemical analysis in bulk, benthic and planktic foraminiferal calcite. These tools will be used to reconstruct the quantitative records of ocean temperature, deep sea carbonate saturation, carbon cycle perturbation and continental ice volume that are needed to develop realistic models of the factors controlling past climate and CCD change.
Training
The successful candidate will enrol in the NOCS Graduate School where they will receive specialist training in oral and written presentation skills, and state of the art analytical skills in a world class geochemical facility. They will also receive training in foraminiferal taxonomy, taphonomy, geochemistry and age model development.
Wider Implications
The successful completion of this study will enhance our understanding of an important period in earth history. IPCC predicts that, under business as usual scenarios, by 2100, atmospheric CO2 levels on Earth will approach the concentrations thought to have been responsible for Eocene greenhouse conditions. The Newfoundland Ridge area is famous because it is the resting place of RMS Titanic that sank on route from Southampton, UK to New York City, USA in April 1912 after colliding with an iceberg.
Background Reading
Coxall HC Wilson PA Palike H Backman J Lear CH (2005) Rapid stepwise onset of Antarctic glaciation and deeper calcite compensation in the Pacific Ocean: Nature 433, 53—57.
DeConto RM, Pollard D, Wilson PA, Pälike H, Lear CH & Pagani M (2008) Thresholds for Cenozoic bipolar glaciation: Nature, 455, 652-656.
Lyle MW Olivarez Lyle A Backman J Tripati A Biogenic sedimentation in the Eocene equatorial Pacific: the stuttering greenhouse and Eocene carbonate compensation depth, in Lyle, M., Wilson, P., and Firth, J., eds., Proc. ODP, Sci. Res. 199: College Station TX, Ocean Drilling Program, p. 1-35 doi:10.2973/odp.proc.sr.199.219.2005.
http://www-odp.tamu.edu/publications/199_SR/219/219.htm
Palike H Norris RD Herrle J Wilson PA Coxall HK Lear CH Shackleton NJ Tripati AK Wade BS (2006) The Heartbeat of the Oligocene climate system: Science, 314, 1894-1898.
For enquiries about this project, please contact paul.wilson@noc.soton.ac.uk.
University of Southampton. Job opportunity.
