In order to limit warming to 1.5 degrees Celsius above the pre-industrial period, global carbon dioxide emissions must reach net-zero by around the middle of the 21st century and become negative thereafter . A net-zero emission level requires that any remaining emission sources are balanced by processes that remove carbon dioxide from the atmosphere.
In June 2019, the UK Government passed legislation that commits the nation to reach net-zero greenhouse gas emissions by the year 2050. The Committee on Climate Change estimated that under an ambitious scenario this reduction is potentially achievable, assuming that around 20-30 MtCO2e (carbon dioxide equivalents) is removed from the atmosphere by vegetation each year, through afforestation, agroforestry, and hedge growing [2, 3].
In order to be removing 20-30 MtCO2e per year from the atmosphere by 2050, advice from the Committee on Climate Change and the Centre for Ecology and Hydrology  indicates that afforestation in the range 30,000 – 50,000 hectares (1 hectare is approximately the size of an international rugby pitch) per year will be required in the UK. Tree planting targets at this level are only achievable alongside substantial changes to the management of UK rural landscapes, i.e., conversion of current pastureland to forests.
Trees and other vegetation take carbon dioxide from the air as they grow, but they also impact the climate and the composition of the atmosphere in numerous other ways by influencing the concentration of a number of pollutants (i.e., particulate matter and ozone). This project will combine a hierarchy of computer models, spanning from emissions accounting tools to 3D atmospheric chemistry models, with observational data to develop a framework within which the impacts of tree planting and landscape restoration can be explored, to answer questions such as:
- How much of a contribution to reaching net-zero greenhouse gas emissions can afforestation and landscape restoration in the UK realistically provide?
- How sensitive is this plan to the level of climate change that the UK experiences in the future?
- What are the co-benefits (e.g., removal of particulate pollution via deposition onto vegetation) of this level of tree planting?
- Are there any counter-productive side-effects (e.g., production of ozone due to emission of biogenic volatile organic compounds from vegetation) associated with this level of afforestation? How do these side-effects change as emissions from other sectors (i.e., transport) decline?
You will have a background in environmental science, geography, meteorology, chemistry, physics, mathematics. You will join the Biosphere – Atmosphere Group within the Institute for Climate and Atmospheric Science (ICAS) and become a member of the Leeds Ecosystem, Atmosphere and Forest (LEAF) Centre. You will benefit from training in both specific technical and in transferable skills provided by the PANORAMA DTP and those offered by the University of Leeds. You will have the opportunity to spend time working with the external project partners at different locations around the UK.
- Intergovernmental Panel on Climate Change, “Special Report on Global Warming of 1.5°C”, 2018: https://www.ipcc.ch/sr15/
- Committee on Climate Change, “Net Zero: The UK’s contribution to stopping global warming”, 2019: https://www.theccc.org.uk/publication/net-zero-the-uks-contribution-to-stopping-global-warming/
- Committee on Climate Change, “Land use: Reducing emissions and preparing for climate change”, 2018: https://www.theccc.org.uk/publication/land-use-reducing-emissions-and-preparing-for-climate-change/
- Centre for Ecology and Hydrology & Rothamsted Research, “Quantifying the impact of future land use scenarios to 2050 and beyond – Final Report”, 2018: https://www.theccc.org.uk/publication/quantifying-the-impact-of-future-land-use-scenarios-to-2050-and-beyond-centre-for-ecology-and-hydrology-and-rothamsted-research/