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Air Quality in a changing climate: improved understanding from Earth system modelling

Dr Steve Arnold (SEE), Prof. Dominick Spracklen (SEE), Dr Steven Turnock (Met Office)

Project partner(s): UK Met Office (CASE)

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Poor air quality affects major cities in regions all around the planet, including the UK and Europe, leading to millions of premature deaths every year worldwide. Mitigation measures to improve air quality and climate are inherently interlinked, as changes to Near Term Climate Forcers (NTCF), such as tropospheric ozone and aerosols, impact both atmospheric pollution abundances and climate. A changing climate can affect chemical and physical processes in the atmosphere controlling spatial and temporal distributions of air pollutants. Understanding Earth system feedbacks on NTCF and air quality are important within a future climate context, as feedbacks could result in "climate penalties", reducing or negating the effectiveness of emission reductions targeting improvement of air quality.

There are numerous ways for air quality and climate to interact and feedback on to one another, including ventilation rates, large scale circulation, wet and dry depositions rates, chemical production and loss rates, temperature, natural emission rates and background concentrations. The impacts of NTCFs on climate offer the opportunity for developing emission mitigation strategies that have co-benefits for air quality improvement and climate change mitigation. However, the interactions between climate change, air quality, and feedbacks on the Earth system are currently poorly understood.

The recent development of a new UK Earth System Model (UKESM) couples together various Earth system modelling components and their interactions into a single model framework, including atmospheric chemistry and aerosol interactions with land surface processes such as emissions of biogenic volatile organic compounds (BVOCs) and emissions from fires. This increased complexity presents the opportunity for a novel study into interactions and feedbacks between air quality and climate, driven by Earth system interactions and responses in the context of future policies relating to climate and air quality.

The over-arching project aim is to understand and quantify how Earth system feedbacks affect air quality.

The project will address the following research questions:

Q1. What are the key Earth system interactions impacting the concentrations of air pollutants (aerosols, ozone)? How do these interactions change under a future warming climate?

Q2. What are the magnitudes of individual Earth system feedback mechanisms linking changes in climate and air quality?

Q3. To what extent will Earth system feedback mechanisms reduce the efficacy of future air quality policies targeting emission reductions of NTCFs? How much do individual mechanisms reduce the benefits from future air quality policies?

The student will analyse UKESM simulations to identify important Earth system interactions (Q1). In order to delve deeper into understanding specific processes, and investigate and quantify feedback mechanisms, the student will carry out their own additional simulations (Q2). Future simulations with the UKESM will be used to quantify the impact of feedback mechanisms on future air quality under both high and low air pollutant emission scenarios and different future climates (Q3).

The student will be co-supervised by the UK Met Office, and will be part of the UK contribution to the AerChemMIP project but also to the wider global multi-model intercomparison that would be undertaken as part of AerChemMIP?s contributions to CMIP6. This would present the opportunity for research and development both within the UK scientific community but also around the globe. The student will benefit from training in expertise in both numerical atmospheric chemistry-climate modelling and analysis of large geophysical datasets. The student will be involved in analysis of a large suite of Earth system model simulations undertaken as part of the international AerChemMIP model comparison project, and will design and run their own model experiments on the Met Office supercomputing facility.

The student will join a group of around 8 students and postdoctoral researchers working on projects in atmospheric composition and its links to climate, air quality and the biosphere. For more information about our research and recent publications, see: We encourage interested applicants to get in touch and arrange an informal visit to Leeds to meet and talk informally with the group.

Click here for a full project description.

Related undergraduate subjects:

  • Atmospheric science
  • Chemistry
  • Computer science
  • Earth system science
  • Environmental science
  • Geography
  • Mathematics
  • Meteorology
  • Natural sciences
  • Physical geography
  • Physics