School of Earth and Environment

Climate and Atmospheric Science (ICAS) PhD Projects

Arctic climate change driven by aerosol

Supervisors: Prof Ken Carslaw and Dr Graham Mann (National Centre for Atmospheric Science)

The climate of the Arctic is changing faster than almost everywhere else on Earth. Recent studies have shown that a major cause of this change is aerosol pollution. Aerosols (small particles in the atmosphere) derived from pollution emissions have multiple complex effects on the Arctic. The light-absorbing material in soot can have a direct warming effect both in the atmosphere and when the particles deposit on snow. Other material, such as sulphates from industrial emissions, can lead to the formation of additional cloud droplets and a substantial impact on the fragile cloud systems in the Arctic. Over the last 20 years the aerosol pollutants have decreased in the Arctic (Fig 1), and the net effect seems to have been a warming (Fig 2), but there are many open questions that remain to be resolved by combining sophisticated global atmospheric models and observations.

This project will use global aerosol and climate models developed at Leeds and in partnership with the Met Office to study the long-term trends in Arctic aerosol and the impacts on climate. The student will be able to adapt these models to include new processes and knowledge, compare them against observations, and make predictions of climate change. In addition to the effects of air pollution, it will be important to study the effect of reductions in sea ice on emissions from the Arctic ocean (sea spray and biological material) in models that combine these important feedbacks.

Objectives

  1. Use state-of the-science global aerosol and climate models to simulate the changes in Arctic aerosol over the industrial period.
  2. Compare the models with observations
  3. Quantify the effect of aerosol changes on radiative forcing and climate
  4. Make future predictions of Arctic climate change based on IPCC emissions scenarios.

Potential for high impact outcome

Figure 2 demonstrates how important Arctic climate change is. Our current understanding of causes and effects is very poor, so new model simulations that capture observed changes in aerosol are going to be a major step forward.

Training

This PhD provides excellent opportunities to learn how to develop and run advanced climate models that are used in IPCC assessments by the Met Office. Prof Ken Carslaw’s aerosol research group has a long track record of developing and using these models, and has trained many PhD students who started from a very limited knowledge of computing. The group has a dedicated support and research scientist (Dr Kirsty Pringle) who can provide support and training in the use of the models. The student will benefit from being immersed in a very active research group with several postdocs and PhD students and strong links to the atmospheric chemistry, paleo, and meteorology groups. There will be an opportunity to attend the NCAS Earth System Science summer school at the start of the PhD.

Further reading

We recommend that you visit the global aerosol modeling web page to find out the sorts of exciting things we study: http://researchpages.net/glomap

Concerning Arctic aerosol and climate change, we recommend:

  • McConnell, JR; Edwards, R; Kok, GL, et al., 20th-century industrial black carbon emissions altered arctic climate forcing, Science, 317, 5843, 1381-1384, 2007.
  • Law, K. S. and Stohl, A., Arctic air pollution: Origins and impacts, Science, 315, 1537–1540, 2007.
  • Quinn, P. K., Bates, T. S., Baum, E., Doubleday, N., Fiore, A. M., et al., Short-lived pollutants in the Arctic: Their climate impact and possible mitigation strategies, Atmos. Chem. Phys., 8, 1723–1735, 2007. http://www.atmos-chem-phys.net/8/1723/2007/