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C445: CONTEST: Feedbacks between COmpositioN and climate in The Earth SysTem (Lead Supervisor: Alexander Archibald, Chemistry)

Supervisors: Alexander Archibald (Chemistry) and Gerd Folberth (Met Office) 

Importance of the area of research:

Feedbacks on climate from changes in trace gases and aerosols exhibit a range of sensitivities, both enhancing and offsetting the effects of changes in atmospheric CO2 (Archibald et al., 2011). These composition-climate feedbacks represent significant uncertainties in our ability to accurately simulate climate change and urgently need to be addressed. The recent improvements in our understanding of the atmospheric chemistry of gases emitted from vegetation and the development of a new Earth System Model (UKESM-1) put us in a position where we can now for the first time comprehensively investigate these important atmospheric composition-climate feedbacks.

Project summary:

Climate change is a forcing-feedback problem. Changes in radiative forcing have feedbacks on temperature, sea ice etc. Some of these are well known (the water vapour feedback) but others are poorly understood and are just emerging as being important. CONTEST will use a new Earth system model (UKESM-1) to deliver the first quantification of the size and sign of the composition-climate feedback parameter that underpins the role of emissions of trace gases and aerosols produced by natural sources. By performing simulations over a range of CO2 levels, we will determine the dependence of the feedbacks on the background climate state. This innovative project will result in improved understanding of the sensitivity of natural composition-climate feedback processes, which are key to improving our understanding of the Earth system.

What the student will do:

The student will use UKESM-1 to study composition-climate feedbacks, validating the model results against a wide array of observations from satellites, aircraft and in situ observations. They will perform a series of experiments that perturb natural emissions of trace gases from sources such as lightning, vegetation and the oceans. The difference between simulations with and without perturbations in emissions can be used to then study the feedbacks the emissions have. Simulations will be run in both atmosphere only and full Earth system model mode. Contrasting these different experiment types will enable the student to understand the effects of the atmospheric feedbacks on global climate through analysis of the radiation and energy budgets.

Please contact the lead supervisor directly for further information relating to what the successful applicant will be expected to do, training to be provided, and any specific educational background requirements.

References:

Archibald et al., 2011. Geophy. Res. Letts.

Kulmala et al., 2014. Boreal Env., Res.

Unger and Yu 2014. Geophy. Res. Letts.

Follow this link to find out about applying for this project.

Other projects available from the Lead Supervisor can be viewed here.

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