Project highlights

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


The sequestration of carbon in terrestrial vegetation and soils contributes to the removal of atmospheric CO2 and is an important process in global climate regulation. Today, the amount of carbon stored in the atmosphere is similar to that stored in vegetation, with significantly more carbon stored in soils. A delicate balance between carbon uptake through photosynthesis and carbon loss via respiration and organic matter degradation controls the relative size of these terrestrial carbon stocks. While additional CO2 in the atmosphere tends to increase the vegetation biomass in response, the impact of warmer temperatures and moisture changes on respiration and degradation rates could lead to losses in terrestrial carbon storage. These terrestrial carbon cycle feedbacks remain a critical source of uncertainty in response to future CO2 release, particularly over timescales that extend beyond the end of this century.

The objective of this PhD project is to quantify how carbon storage in soils and vegetation will vary under long-term future CO2 concentrations and to study the implications for related Earth system processes, including rates of weathering and carbon burial. A key goal of the project is to evaluate Earth system model representation of the carbon fluxes that lead to a growth or decay of terrestrial carbon stocks for incorporation into intermediate complexity model frameworks. A number of Earth system models of varying complexity will be assessed to reconstruct changes in the size of global carbon stocks in the future, while also simulating feedbacks with the climate system over long timescales. The same modelling approach will also be applied to assess the behaviour of terrestrial carbon stocks at key intervals through Earth history, starting with the widespread emergence of land plants about 400 million years ago. The project will evaluate how well model representation of terrestrial carbon fluxes captures the influence of environmental changes that likely influenced the sensitivity of photosynthesis and respiration rates throughout the Phanerozoic Eon. The student will gain skills in numerical modelling techniques 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 pointing down symbolise terrestrial carbon uptake by photosynthesis and soil carbon uptake via leaf litter deposition, while red arrows pointing up symbolise carbon loss to the atmosphere by respiration or organic matter degradation. A yellow sun and radiation lines and a grey raincloud are in the sky above the graphic.

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
  • Organisms and Ecosystems


Project investigator

Dr. Sarah Greene, University of Birmingham ([email protected])


Dr. Pam Vervoort, University of Birmingham (

Dr. Sandra Kirtland Turner, University of California Riverside (s[email protected])

Dr. Chris Jones, Met Office ([email protected])

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 Dr. 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

I encourage and welcome prospective applicants to contact me (Sarah Greene – [email protected]) in advance of applying 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 questions about pulling 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.

If you wish to apply to the project, applications should include:

  • A CV with the names of at least two referees (preferably three and who can comment on your academic abilities)
  • Submit your application and complete the host institution application process via: and go to Apply Now in the PhD Geography and Environmental Science (CENTA) section. Please quote CENTA23_B8 when completing the application form.

Applications to be received by the end of the day on Wednesday 11th January 2023. 

Additional information for international applicants

  • All international applicants must ensure they can fulfil the University of Birmingham’s international student entry requirements, which includes English language requirements.  For further information please visit
  • Please be aware that CENTA funding will only cover University fees at the level of support for Home-fee eligible students.  The University is only able to waive the difference on the international fee level for a maximum of two successful international applicants.

Possible timeline

Year 1

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.

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.

Further reading


The primary research tool that will be used in this project is Earth system modelling. As this is a desk-based project and the PhD student could work from anywhere with a computer terminal and internet access, the project delivery is unlikely to be affected by the pandemic.