The QMEE CDT Project proposal database

Welcome to the QMEE CDT Project proposal database. This is a live list of projects proposals put forward by PIs across the CDT partner institutions

PIs/Supervisors will continue to add projects to this list over the next few months, so do keep checking back! You can search the projects using the box below: simply enter some text and press Search to do a text search across all the database fields. If you want to search more finely, the search tool also allows you to search on particular details of the project descriptions: you will see these finer search options appear if you click on the search box.

Click on the view button next to a project to get the full proposal description. If you want to download project details, either for all projects, or for a subset you have searched for, then click on the 'Download details' button.

Investigating the response of plants and soils to environmental changes using carbon isotope modelling
Terrestrial ecosystems presently remove about a quarter of the CO2 emissions from human activities that are the main cause of climate change, but the attribution of terrestrial CO2 uptake to specific processes is still under debate. Further, the efficiency of terrestrial CO2 uptake is projected to decline in the future. The primary uncertainties in the simulation of the present and future CO2 sink in terrestrial ecosystems are the magnitude of the CO2 fertilization effect and the rate of turnover of carbon in vegetation and soils. New metrics for evaluating these processes in models are needed. This project will advance the modelling and model-data analysis of carbon isotopes in terrestrial ecosystem models in order to evaluate global ecosystem dynamics and model behaviour. Carbon assimilated by plants is depleted in 13C, relative to atmospheric CO2, due to fractionation processes that depend on leaf-level carbon exchange. Stomatal opening, and resulting 13C/12C fractionation, can vary due to changes in atmospheric CO2 and water vapour concentrations. Previous studies have used 13C/12C ratios in tree rings to estimate changes in internal leaf CO2 concentration (e.g. Frank et al. 2015), indicating that plants have increased water use efficiency while also increasing photosynthesis in recent decades. New opportunities to investigate large-scale ecosystem changes are now available using atmospheric measurements of 13C/12C in CO2 (Keeling et al. 2017) together with global models. Tracking the excess radiocarbon (14C) produced by nuclear weapons testing in the 1950s and 60s provides a sensitive metric of the rate of carbon turnover. This technique is relatively well-developed on the plot-scale, but global modelling of 14C in terrestrial ecosystems is still underdeveloped. New work combining plot-scale radiocarbon data with off-line simulations based on global ecosystem models suggests that soil carbon turnover is generally too rapid in models (He et al. 2016). Additional constraints on total ecosystem carbon turnover from an observation-based estimate of the global biospheric 14C inventory (Naegler and Levin 2009) could be exploited with a similar approach. This project will develop the simulation of carbon isotopes in ecosystem models and their comparison to isotopic data. First, we will develop off-line simulations, or “emulators,” of 13C and 14C for existing terrestrial models that do not explicitly simulate carbon isotopes. These emulators will use other variables already included in models and model parameters that relate to processes governing carbon isotopes, including carbon fluxes, residence times, and internal leaf CO2 concentrations. Then, we will implement carbon isotopes in the JULES model that comprises the terrestrial component of the UKESM. Off-line and on-line simulation of carbon isotopes in JULES will allow us to assess the capability of the emulators and how their use could be expanded in model-data evaluation for the current phase of the Coupled Model Intercomparison Project, CMIP6. The interdisciplinary supervisory team has expertise on isotopic observations in atmospheric CO2 (Graven), tree rings (Hemming), and leaves (Prentice), as well as on the development of ecological theory and modelling (Prentice, Hemming, Jones). The project will enable new directions in ecosystem modelling and model evaluation, addressing recommendations from the Coupled Climate-Carbon Cycle Model Intercomparison (C4MIP, part of CMIP6).
Heather Graven
Colin Prentice
Chris Jones, Met Office, chris.d.jones@metoffice.gov.uk; Deborah Hemming, Met Office, debbie.hemming@metoffice.gov.uk
Development of mathematical theory, Computing, Quantitative data analysis, Ecological observations / data collection
Heather Graven
The student will acquire skills in 1. Development of ecological theory and models involving carbon isotopes, 2. Development of new applications and validation for existing theory/methods/models, 3. Model benchmarking and evaluation, 4. Off-line simulation/emulators for complex models, 5. Analysis and manipulation of large datasets and model output
14C is not fully incorporated into any terrestrial ecosystem models, and 13C in only a few models, despite the potential for model evaluation and analysis using isotopes. This project will advance the incorporation of carbon isotopes into JULES and other models. It will also develop novel off-line emulators to simulate 14C and 13C for models where they are not explicitly included.
The project addresses ecological theories underlying global terrestrial ecosystem models related to photosynthesis and carbon cycling. In particular, the response of photosynthesis to rising CO2 is expected to create isotopic signatures through stomatal and other physiological changes, and isotope dynamics are sensitive to large-scale carbon-climate interactions and overall model structure.
The project will evaluate the uptake and storage of carbon in terrestrial ecosystems simulated by current Earth System Models that are used to assess goals for climate change mitigation and greenhouse gas emissions reductions from the Paris Agreement. It will investigate modelled linkages in terrestrial carbon and water cycling that also affect other model applications such as weather forecasting.
This project will develop new methods for model evaluation and model intercomparison that will enable finer constraints to be placed on terrestrial ecosystem responses to global environmental change. It will investigate large discrepancies that currently exist between carbon stocks and fluxes in different models and different observational estimates of plant water use efficiency trends.
This project examines how photosynthesis and carbon cycling in terrestrial ecosystems responds to atmospheric CO2 and environmental changes, and how the responses are represented in models, involving the disciplines of Terrestrial ecology, Biogeochemistry and global change, Earth System Modelling, Plant physiology, Ecohydrology, Atmospheric science, Soil science and Climate physics.
Climate and climate change, Ecosystem-scale processes and land use, Ecological/Evolutionary tools, technology & methods
The student will attend training sessions for the JULES and UKESM models held regularly, and will benefit from training by the Met Office collaborators and their colleagues. H. Graven will provide training on developing simple model emulators and on atmospheric transport modelling. Other training offered by NERC, on e.g. uncertainty, will be pursued during the PhD.
Imperial, Met Office, NERC training centres
No
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