University of Exeter funding: NERC GW4+ DTP PhD studentship

Using low-order climate models to identify safe pathways for the Atlantic Ocean Circulation. PhD in Mathematics (NERC GW4+ DTP) Ref: 3698

About the award


Lead Supervisor

Prof Peter Ashwin, Department of Mathematics, College of Engineering, Mathematics and Physical Sciences, University of Exeter

Additional Supervisors

Prof Paul Valdes, School of Geographical Sciences, University of Bristol

Location: University of Exeter, Streatham Campus, Exeter, EX4 4QJ

This project is one of a number that are in competition for funding from the NERC GW4+ Doctoral Training Partnership (GW4+ DTP).  The GW4+ DTP consists of the GW4 Alliance of research-intensive universities: the University of Bath, University of Bristol, Cardiff University and the University of Exeter plus five unique and prestigious Research Organisation partners: British Antarctic Survey, British Geological Survey, Centre for Ecology & Hydrology, the Natural History Museum and Plymouth Marine Laboratory.  The partnership aims to provide a broad training in the Earth, Environmental and Life sciences, designed to train tomorrow’s leaders in scientific research, business, technology and policy-making. For further details about the programme please see

For eligible successful applicants, the studentships comprises:

  • A stipend for 3.5 years (currently £15,009 p.a. for 2019/20) in line with UK Research and Innovation rates
  • Payment of university tuition fees;
  • A research budget of £11,000 for an international conference, lab, field and research expenses;
  • A training budget of £3,250 for specialist training courses and expenses.
  • Travel and accommodation is covered for all compulsory DTP cohort events
  • No course fees for courses run by the DTP

We are currently advertising projects for a total of 10 studentships at the University of Exeter.


Students who are resident in EU countries are eligible for the full award on the same basis as UK residents.  Applicants resident outside of the EU (classed as International for tuition fee purposes) are not eligible for DTP funding. Residency rules are complex and if you have not been resident in the UK or EU for the 3 years prior to the start of the studentship, please apply and we will check eligibility upon shortlisting.

Project Background

As international efforts intensify to avoid dangerous climate change, it becomes increasingly important to develop pathways that minimise the risk of taking the climate system past a threshold or 'tipping point' which triggers some effectively irreversible change. The Atlantic Ocean's Meridional Overturning Circulation (AMOC) transports large amounts of heat from low latitudes into the North Atlantic, where it is given up to the atmosphere and plays a critical role in maintaining the relatively mild climate of western Europe. It is believed that in the past a collapse of the AMOC played a part in some extended cold periods seen in palaeoclimatic records. How would we know if the AMOC was approaching such a tipping point, and are there 'safe' pathways towards an eventual target climate that minimise the chance of crossing one? These questions are the motivation for this PhD project.

Project Aims and Methods 

Detailed earth system models are an essential tool to assess the climate, but their computational expense limits the scenarios that can be explored. The objective of this PhD is to explore a class of simpler, computationally cheap models [1] to provide insight into when the AMOC might pass a tipping point, and identify ways in which this could be avoided. The work builds on a recent study [2] that showed that tipping could occur for a variety of reasons; for example in some climate change scenarios the AMOC always remained stable in principle, but still if the climate change proceeded too fast the AMOC would collapse. Key questions for the project are: (a) showing that the simple model captures the essential dynamics of AMOC thresholds that are seen in GCM experiments and (b) using modern mathematical methods to analyse the dynamics of the AMOC thresholds in the simple model for various climate change pathways. The project will link simple models of future and past climate change to AMOC tipping models; it will then use rate-dependent tipping in dynamical systems to analyse circumstances under which tipping could occur, and possible climate stabilisation pathways that reduce the chance of tipping. This will suggest designs for additional GCM experiments to check predictions of the simple model.


Global conveyor belt, including the Atlantic Meridional Overturning Circulation (AMOC)


Basin of attraction for the AMOC ‘on state’ for a low-order model of global circulation.

Candidate Requirements

The project will be suitable for a candidate with a first degree or masters in mathematics (or similar degree with strong and applicable mathematical skills) as well as some knowledge of dynamical systems theory/computational modelling. The candidate should have an interest in, but not necessarily experience of, climate modelling.

CASE or Collaborative Partner

The CASE partner (Met Office) sees the proposed research as being of high relevance to understanding AMOC tipping and developing a better understanding of policy relevance. The student will benefit from working closely with the partner on analysis of GCM runs and design of GCM experiments. This will give the student a good experience of working within the partner as well as in an academic research environment.


At Exeter, they will get training in the mathematics of dynamical systems, computational modelling and climate systems. At Bristol, the group of Prof Valdes will provide training in palaeoclimatology. The student will work with scientists at the Met Office Hadley Centre who are analysing models and policy at the forefront of AMOC research. The groups at Exeter, Bristol and the Met Office are partners in the major EU project TiPES (Tipping points in the Earth System) that runs from 2019-2023 and will enable collaboration with relevant climate science groups at Utrecht, Copenhagen and Potsdam.

References / Background reading list

[1] Wood, RA, Rodrigues, JM, Smith RS, Jackson LC, Hawkins E. 2019 Observable, low-order dynamical controls on thresholds of the Atlantic Meridional Overturning Circulation. Climate Dynamics (to appear)

[2] Alkhayuon H, Ashwin P, Jackson LC, Quinn C, Wood RA. 2019 Basin bifurcations, oscillatory instability and rate-induced thresholds for Atlantic meridional overturning circulation in a global oceanic box model. Proc. R. Soc. A 475: 20190051.

Entry requirements

Applicants should have obtained, or be about to obtain, a First or Upper Second Class UK Honours degree, or the equivalent qualifications gained outside the UK.   Applicants with a Lower Second Class degree will be considered if they also have Master’s degree.  Applicants with a minimum of Upper Second Class degree and significant relevant non-academic experience are encouraged to apply.

All applicants would need to meet our English language requirements by the start of the  project

How to apply

In the application process you will be asked to upload several documents.  Please note our preferred format is PDF, each file named with your surname and the name of the document, eg. “Smith – CV.pdf”, “Smith – Cover Letter.pdf”, “Smith – Transcript.pdf”.

  • CV
  • Letter of application outlining your academic interests, prior research experience and reasons for wishing to undertake the project.
  • Transcript(s) giving full details of subjects studied and grades/marks obtained.  This should be an interim transcript if you are still studying.
  • If you are not a national of a majority English-speaking country you will need to submit evidence of your current proficiency in English.

Reference information
You will be asked to name 2 referees as part of the application process, however we will not expect receipt of references until after the shortlisting stage. Your referees should not be from the prospective supervisory team.

If you are shortlisted for interview, please ensure that your two academic referees email their references to the, 7 days prior to the interview dates.  Please note that we will not be contacting referees to request references, you must arrange for them to be submitted to us by the deadline.

References should be submitted by your referees to us directly in the form of a letter. Referees must email their references to us from their institutional email accounts. We cannot accept references from personal/private email accounts, unless it is a scanned document on institutional headed paper and signed by the referee.

All application documents must be submitted in English. Certified translated copies of academic qualifications must also be provided.

The closing date for applications is 1600 hours GMT Monday 6 January 2020.  Interviews will be held between 10 and 21 February 2020.  For more information about the NERC GW4+ DPT please visit

If you have any general enquiries about the application process please email  Project-specific queries should be directed to the lead supervisor.

Data Sharing
During the application process, the University may need to make certain disclosures of your personal data to third parties to be able to administer your application, carry out interviews and select candidates.  These are not limited to, but may include disclosures to:

  • the selection panel and/or management board or equivalent of the relevant programme, which is likely to include staff from one or more other HEIs;
  • administrative staff at one or more other HEIs participating in the relevant programme.

Such disclosures will always be kept to the minimum amount of personal data required for the specific purpose. Your sensitive personal data (relating to disability and race/ethnicity) will not be disclosed without your explicit consent.


Application deadline:6th January 2020
Value:£15,009 per annum for 2019-20
Duration of award:per year
Contact: PGR Enquiries