Overview

Project Highlights

  • Determine how the oceans and global climate evolved across an ancient global warming event
  • Constrain the dominant driver(s) and key feedbacks associated with past environmental change
  • Learn a diverse range of key geochemical, sedimentological and faunal techniques for reconstructing past environments
  • Join a world-class team of scientists working to understand the dynamics of past high-CO2 worlds

The Eocene epoch (34-56 million years ago; Ma) was characterised by warmer global temperatures and higher atmospheric carbon dioxide levels than today and small or no ice-sheets. These high-CO2 worlds were traditionally considered to be relatively climatically stable but we now know that they were punctuated by numerous transient global warming or ‘hyperthermal’ events[1] that are perhaps our best analogues for anthropogenic change.

One such warming event was the Middle Eocene Climatic Optimum (MECO) which reversed a long-term global cooling trend, ~40 (Ma)[2]. During the MECO global ocean temperatures rose by ~3-5 °C, surface ocean nutrient levels increased, the carbonate compensation depth shoaled by >1 km in all ocean basins, and there were large shifts in both floral and faunal communities[2,3].

However, our inability to reconcile observations with basic carbon cycle theory across the MECO highlights major gaps in our understanding of the link between the climate and carbon cycle over intermediate timescales (~50-500 kyrs)[4]. This is exacerbated by a dearth of records against which to test key hypotheses. For instance, we still have very poor constraints on the rate and timing of carbon input, the magnitude of tropical and high northern latitude temperature change and the driver(s) of the environmental change (e.g., volcanism vs. ocean circulation changes)[4]. This project will fill these critical gaps in our understanding of the global climate system during past high-CO2 intervals and ultimately help to reduce uncertainty related to predicting future climatic changes.

The IODP ship Joides Resolution leaving Hawaii (William Crawford IODP/TAMU) and below fossil foraminiferal tests.

Methodology

This project will generate new high-temporal resolution records of global climate and carbon cycling across the MECO event at multiple International Ocean Discovery Program (IODP) sites. This may also include new highly expanded Eocene sediment sequences recently recovered by IODP Exp. 342 off the Newfoundland margin that offer the opportunity to reconstruct the event at unprecedented temporal resolution. This PhD project will involve detailed taxonomic, and geochemical (d13C and d18O, trace element ratios) study of foraminiferal tests preserved in deep-sea sediments spanning the MECO to constrain a range of environmental parameters including; temperature, ice volume, and carbonate chemistry. These data will be supplemented with faunal and sediment analyses, e.g., scanning election microscopy to determine test preservation, and fragmentation and %CaCO3 records to constrain deep ocean chemistry.

Training and Skills

CENTA students are required to complete 45 days training throughout their PhD including a 10-day placement. In the first year, students will be trained as a single cohort on environmental science, research methods and core skills. Throughout the PhD, training will progress from core skills sets to master classes specific to the student's projects and themes. 

The student will gain experience in processing sediment samples for micropalaeontological investigation and detailed training in Eocene foraminiferal taxonomy, and taphonomy. They will learn how to work in clean labs, generate and interpret carbon and oxygen stable isotope and trace element ratios from foraminiferal tests as well as a suite of other sedimentological proxies. The student will also develop skills in multivariate statistical techniques, graphing and mapping in the free R environment. These skills are highly transferable and will enable the student to progress as a, micropalaeontologist (in academia or industry) or palaeoceanographer.

Timeline

Year 1: Complete literature review. In parallel, receive training in laboratory protocols, sediment sample processing, and taxonomy of Eocene benthic and planktic foraminifera. Learn to use scanning electron microscope to evaluate foraminiferal test taphonomy (B’ham). Pick foraminifera from samples for stable isotope analyses (B’ham) and trace element analyses (OU). Presentation of preliminary results at the Micropalaeontological Society’s Foraminifera and Nannofossil spring meeting in Freiburg, Switzerland.

Year 2: Continue picking samples as necessary and generate bulk of geochemical and sedimentological data. Data interpretation and develop manuscript 1. Presentation of results at the 13th International Conference on Palaeoceanography, in Sydney, Australia.

Year 3: Complete outstanding analytical work, data processing and interpretation. Preparation of remaining manuscripts and thesis write-up. Presentation of results at (provisionally) ‘Climatic and Biotic Events of the Paleogene’ in 2020.