2025-L2 Tracing Late Miocene sea surface temperature in the equatorial Pacific during past El Niño-like climate states

Project highlights

Investigating how Late Miocene shifts between El Niño-like and La Niña-like climate states impacted Pacific sea surface temperatures and the global heat budget

Exploring the impact of prolonged El Niño-like warm climates on foraminifera and the marine biosphere

Working on deep-marine sediments recovered by the International Ocean Discovery Program (IODP) and ability to interact with others from this large international research community.

Overview

During the Late Miocene (~11.6-5.3 Ma), Earth’s climate was much warmer, similar to that predicted by the IPCC for the year 2100. A prolonged El Niño-like state is thought to have dominated the equatorial Pacific for part of the Late Miocene, with warm waters spreading across the entire equatorial region. The modern El Niño cycle causes significant global climate anomalies far afield from the Pacific Ocean. This project aims to improve understanding of the potential presence and impacts of prolonged El Niño-like conditions in a past warm climate similar to those predicted for the future.

Three main hypotheses exist about the state of the equatorial Pacific during the Late Miocene: 1) a Late Miocene permanent El Niño-like state (e.g., Ravelo et al., 2014), 2) alternating El Niño-like (9.6-6.5 Ma) and La Niña-like (6.5-6.1 Ma) states (e.g., Nathan and Leckie, 2009; Drury et al., 2018), or 3) modern thermal gradients since ~12 Ma (e.g., Zhang et al., 2014). A recent project generated new high-resolution stable oxygen (δ18O) isotope data in the Western Pacific Warm Pool (WPWP), supporting the case for alternating states (Drury, MIONIÑO, 2019-2022). Now, independent temperature records are needed to establish equatorial Pacific temperature gradients and constrain the impact of local hydrology on foraminiferal δ18O.

This PhD project would focus on generating these missing sea surface and thermocline temperature records in the WPWP using planktonic foraminiferal Mg/Ca analysis paired with clumped isotope (Δ47) thermometry on coccolith-rich sediment. These sediments were recovered by the International Ocean Discovery Program (IODP) and its predecessors. Throughout the project, the DR will be working with IODP material and other researchers from the wider international IODP community. The DR would lead efforts to reconstruct the WPWP thermocline structure and equatorial temperature gradients to establish the impact of alternations between prolonged El Niño-like and La Niña-like conditions. With high-resolution records, the DR can also test the sensitivity of the equatorial Pacific region to astronomical forcing during different climate states. The impact of these different climate states and associated temperature shifts on the biota that lived there will be investigated using multi-species planktonic foraminiferal geochemistry records.

Host

University of Leicester

Theme

Climate and Environmental Sustainability
Organisms and Ecosystems

Supervisors

Project investigator

Dr Anna Joy Drury, [email protected] (University of Leicester)

Co-investigators

Dr Tom Dunkley Jones, [email protected] (University of Birmingham)
Professor Jens Zinke, [email protected] (University of Leicester)
Professor Bridget Wade (University College London)
Dr Thomas Westerhold (University of Bremen)

How to apply

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Methodology

The proposed PhD project will focus on generating Mg/Ca major trace element analysis of planktonic mixed layer and thermocline foraminifera to reconstruct upper water column temperatures in the WPWP, using material and data recovered by the International Ocean Discovery Program (IODP). Clumped isotope Δ47 thermometry on coccolith-rich fine fraction will help constrain long-term temperature changes that may be impacted by changes in seawater Mg/Ca concentration. Scanning electron microscopy to establish specimen preservation and the composition of the isolated sediment fractions. Spectral analysis techniques on the new data will be used to test for any sensitivity changes of sea surface temperatures to astronomical forcing during the changing climate states. Multi-species δ18O and δ13C analyses will be used to trace links between ecological and environmental changes during prolonged warm intervals.

Training and skills

DRs will be awarded CENTA Training Credits (CTCs) for participation in CENTA-provided and ‘free choice’ external training. One CTC can be earned per 3 hours training, and DRs must accrue 100 CTCs across the three and a half years of their PhD.

The DR will become familiar with key Late Miocene foraminifera. They will be trained in preparation and analysis of foraminifera for major trace elements and stable isotopes (O and C) using IRMS and ICP-MS facilities at the University of Leicester. The DR will isolate coccolith-rich sediment for clumped isotope Δ47 analysis, likely at the University of Birmingham. The DR will become familiar with the international programme IODP and encouraged to apply for in IODP training opportunities (i.e., ECORD Training Course). The DR will become part of a collaborative network associated with the original IODP expedition and the MIONIÑO project (https://www.ucl.ac.uk/earth-sciences/research/research-groups/micropalaeontology/research/mionino).

Partners and collaboration

This project builds on the results from several recently completed grants (Horizon2020 MSCA MIONIÑO fellowship; DFG IODP Priority Programme Project) developed collaboratively between the PI and researchers at UCL (Professor Bridget Wade, Professor Paul Pearson), MARUM, University of Bremen (Dr Thomas Westerhold) and UCSC (Professor Ana-Christina Ravelo). The prospective DR will have the opportunity to integrate their results with the data from these studies and discuss their results with collaborators. In addition, the DR will work closely with Dr Tom Dunkley Jones (University of Birmingham) on the isolation of coccolith-rich fine fraction for clumped isotope analysis.

Further details

We welcome any informal queries to: Anna Joy Drury (UoL) [email protected]

To apply to this project: 

You must include a CENTA studentship application form, downloadable from: CENTA Studentship Application Form 2025.

You must include a CV with the names of at least two referees (preferably three) who can comment on your academic abilities.

Please submit your application and complete the host institution application process via: CENTA PhD Studentships | Postgraduate research | University of Leicester.  Please scroll to the bottom of the page and click on the “Apply Now” button.  The “How to apply” tab at the bottom of the page gives instructions on how to submit your completed CENTA Studentship Application Form 2025, your CV and your other supporting documents to your University of Leicester application. Please quote CENTA2025-L2 when completing the application form.

 Applications must be submitted by 23:59 GMT on Wednesday 8th January 2025. 

Possible timeline

Year 1

Literature search and familiarisation with existing datasets available at the target site. The DR will be trained in the cleaning process for foraminiferal trace element analysis and start analysis of the foraminiferal trace element geochemistry. The DR can also pick multispecies planktonic foraminifera for stable isotope analyses.

Year 2

The DR will finish the trace element time series analyses. They DR can familiarise themselves with spectral analysis techniques using existing high-resolution X-ray fluorescence (XRF), core image tracks and foraminiferal stable isotope data, and apply it to the new dataset they’ve generated (potential manuscript 1). The DR can run the multispecies stable isotope and trace element analyses to see the impact of environmental changes on the ecology of planktonic foraminifera (potential manuscript 2).

Year 3

Based on their trace element time series, the DR can determine which samples to target for fine fraction clumped isotope thermometry. The DR will be trained in how to isolate a coccolith-rich size fraction, and use this material for clumped isotope analysis to look at long-term temperature evolution and reconstruct changes in the Mg/Ca composition of seawater (potential manuscript 3). Thesis writing, incorporating the three manuscripts/manuscript drafts.