NERC GW4+ DTP PhD studentship: Early warning of abrupt climate change.

Academic Supervisors:

Main supervisor: Professor Tim Lenton, University of Exeter, Streatham Campus, Exeter

Co-supervisor: Professor Paul Valdes, University of Bristol

Project Description:

The Earth’s climate has changed abruptly many times in the past – especially during the last ice age. These past abrupt climate changes have been linked to shifts between alternative circulation states of the Atlantic Ocean.

Looking ahead there have been widespread concerns that human-induced climate change could also trigger a shift in the Atlantic meridional overturning circulation (AMOC) causing widespread impacts, especially over Europe. This is an iconic example of a potential climate tipping point (Lenton et al. 2008; Fig.1). However, our ability to predict such climate tipping points is currently rather poor. In particular, the state-of-the-art General Circulation Models (GCMs) used for future climate prediction have yet to succeed in simulating past abrupt climate changes. Recently, excitement has been generated by the theory that some approaching tipping points carry generic early warning signals, notably slowing recovery from perturbations (‘critical slowing down’), which can be detected in time-series data using statistical indicators such as rising autocorrelation.

This project will seek to improve our capability to forecast abrupt climate change. You will use a combination of climate modelling, early warning theory, and paleo-data to examine whether past and potential future reorganisations of the AMOC carry detectable early warning signals. Recent simulations with the ‘FAMOUS’ GCM have shown that there are early warning signals in the model world before a slowly forced collapse of the AMOC (Boulton et al. 2014; Fig.2). Furthermore, co-supervisor Paul Valdes has developed a version of FAMOUS in which the degree to which there are alternative stable states in the model can be readily adjusted by changing atmosphere and ocean parameters. The model also simulates the cycling of oxygen isotopes allowing its predictions to be compared with the oxygen isotope record of past abrupt climate changes from ice cores in Greenland. You will examine whether the statistically-based early warning methods can identify versions of the FAMOUS model that exhibit a tipping point, and what early warning signals there are in model simulations and real paleo-data. This will include comparing whether you get the same results in climate metrics (such as time-series of AMOC strength or North Atlantic sea surface temperatures) as you do in simulated paleo-proxies (oxygen isotopes over Greenland).

We seek a highly motivated candidate wanting to gain an Earth system understanding of past and potential future abrupt climate change. Candidates should have a relevant degree and good mathematical skills.

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 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 http://www.exeter.ac.uk/postgraduate/apply/english/ The majority of the studentships are available for applicants who are ordinarily resident in the UK and are classed as UK/EU for tuition fee purposes, however up to 9 fully funded studentships across the DTP are available for EU/EEA applicants not ordinarily resident in the UK. Applicants who are classed as International for tuition fee purposes are not eligible for funding.

To apply: http://www.exeter.ac.uk/studying/funding/award/?id=1933