Project highlights

  • Explore how terrestrial carbon stocks changed over Earth’s geological history in response to climate change, tectonics, and evolution 
  • Improving projections of long-term future terrestrial carbon storage, land-atmosphere-ocean interactions, and carbon-climate feedbacks  
  • Learn Earth system modelling techniques and numerical/coding skills that lend themselves to employment within or outside of academia post-PhD 


Over the last 500 million years, Earth has undergone many changes that drastically altered the behaviour of the global carbon cycle and climate. These include geologically slow changes related to, for instance, plate tectonics or biological evolution, and more rapid changes induced by the release of greenhouse gasses from natural or anthropogenic sources. In response to such environmental perturbations, carbon is repartitioned between the atmosphere, ocean, and terrestrial biosphere with consequences for atmospheric CO2 concentrations and global temperatures. While proxies and tools exist to estimate the mass of carbon stored in the atmosphere and ocean in past and present intervals, we currently do not have a good understanding of how much carbon was/is sequestered in soils and vegetation — a critical missing piece of information that prevents us from assessing the workings of Earth’s system as a whole in past, present, and future environmental scenarios. 

The objective of this PhD project is to quantify with numerical tools how carbon storage in soils and vegetation varied through key intervals in Earth history, from the time of widespread emergence of land plants about 400 million years ago, to the present day, and into the long-term future as a consequence of anthropogenic climate change. A key goal is to evaluate carbon processes that lead to a growth or decay of terrestrial carbon stocks for incorporation into intermediate complexity model frameworks, including the mathematical expressions of biological respiration and photosynthetic fluxes. A number of Earth system models of varying complexity will be assessed to reconstruct changes in the size of global carbon stocks, while also simulating feedbacks within the climate system over long timescales and study implications for related geological processes such as rates of weathering and carbon burial. The project will evaluate how well model representation of terrestrial carbon fluxes captures the influence of environmental changes that likely impacted the sensitivity of photosynthesis and respiration rates throughout the Phanerozoic Eon. The student will gain skills in numerical modelling techniques, coding, and data visualization in an interdisciplinary field with applications to future climate and paleoclimate research.  

Schematic of the representation of the terrestrial biosphere in a gridded Earth system model. Blue arrows symbolise terrestrial carbon uptake by photosynthesis and soil carbon uptake via leaf litter deposition, while red arrows symbolise carbon loss to the atmosphere by respiration or organic matter degradation.

Figure 1: Schematic of the representation of the terrestrial biosphere in a gridded Earth system model. Blue arrows symbolise terrestrial carbon uptake by photosynthesis and soil carbon uptake via leaf litter deposition, while red arrows symbolise carbon loss to the atmosphere by respiration or organic matter degradation. 


University of Birmingham


  • Climate and Environmental Sustainability
  • Dynamic Earth


Project investigator

Sarah Greene, University of Birmingham, [email protected] 


Pam Vervoort (University of Birmingham)

Sandra Kirtland Turner (University of California Riverside)

Chris Jones (Met Office)

How to apply


The processes that lead to growth and decay of terrestrial carbon stocks will be identified and their representation in Earth system models will be evaluated though literature and model review. The terrestrial carbon cycle component in the gridded Earth system model called ‘cGENIE’ will be subjected to extensive testing under a range of conditions and adjustments to the model will be made where needed in order to improve the representation of terrestrial carbon cycle processes.  

To assess the change in terrestrial carbon stocks through time, the student will use the Earth system model cGENIE to investigate the impacts of background climate, feedback strength, and geography on the carbon cycle fluxes.  

Training and skills

Students will be awarded CENTA2 Training Credits (CTCs) for participation in CENTA2-provided and ‘free choice’ external training. One CTC equates to 1⁄2 day session and students must accrue 100 CTCs across the three years of their PhD.  

This project would suit a student with a background in any Earth Science or Climate Science field, including (but not limited to) Geology, Physical Geography, Environmental Science, or Meteorology. Some prior exposure to numerical modelling would be advantageous, but the supervisory team would be happy to consider applicants who enjoy coding but have not yet had the opportunity to try numerical or Earth system modelling first hand. Through the course of the PhD we will provide training in skills including Earth system modelling, model intercomparison, coding, scientific writing and presenting. There are also opportunities to develop skills in science communication, public engagement, and community organising by getting involved in related, ongoing projects in the lead supervisor’s lab group as well as opportunities to learn about working in government and climate-related policy via the supervisory ties to the Met Office. 

Partners and collaboration

The supervisory team includes Drs Sarah Greene and Pam Vervoort at the University of Birmingham, Dr Sandy Kirtland Turner from the University of California Riverside, and Chris Jones from the Met Office. The supervisory team collectively have a wealth of experience using various Earth system models to study the global carbon cycle, past to future. 

Further details

Further details on how to contact the supervisor for this project and how to apply for this project can be found here: 

Prospective applicants please contact me (Sarah Greene – [email protected]) in advance of applying. You are very welcome to ask questions about the project, to discuss whether working with me on this project at the University of Birmingham is a good fit for you, or to ask advice about putting together a strong application. I am also happy to put you in contact with my current and former students to ask questions about their experiences. 

 To apply to this project: 

  • You must include a CENTA studentship application form, downloadable from: CENTA Studentship Application Form 2024. 
  • 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: Please select the PhD Geography and Environmental Science (CENTA) 2024/25 Apply Now button. The CENTA application form 2024 and CV can be uploaded to the Application Information section of the online form.  Please quote CENTA 2024-B17  when completing the application form. 

Applications must be submitted by 23:59 GMT on Wednesday 10th January 2024. 

Possible timeline

Year 1

Review of literature and pre-existing Earth system model representation of terrestrial carbon cycle stocks. Hands on training in Earth system modelling, followed by testing and adjusting the representation of terrestrial carbon storage in the model ‘cGENIE’ under a range of conditions. 

Year 2

Long-term future simulations of terrestrial carbon storage, including evaluating the implications for related Earth system carbon cycle processes.

Year 3

Simulating terrestrial carbon storage in deep time, in response to changes in background factors such as climate, tectonics, and evolution.

The timeline here is only indicative as there is scope for the student to help shape the direction of the project in later years to suit their interests and future career goals. 

Further reading

Lyon et al., 2022. Climate change research and action must look beyond 2100. Global Change Biology, 28(2), pp.349-361, 

Gurung et al., 2022. Climate windows of opportunity for plant expansion during the Phanerozoic. Nature Communications, 13(1), p.4530, 

Schimel, D., et al., 2015. Effect of increasing CO2 on the terrestrial carbon cycle. Proceedings of the National Academy of Sciences, 112(2), pp.436-441,