Admissions > PhD by research > Research Projects > Wildfires as part of the global carbon cycle: quantitative analysis using data assimilation

Wildfires as part of the global carbon cycle:

quantitative analysis using data assimilation

Supervisors: Dr Wolfgang Knorr and Dr Marko Scholze

Brush fires over Kaletzi near Athens, August 2009
(Photo: Aris Messinis/AFP/Getty Images).

Wildfires and biomass burning are not only an interesting ecological and social phenomenon as they can drastically change the characteristics of the land surface [1], they also release large amounts of carbon dioxide into the atmosphere [2]. Accurate estimates of the amount of greenhouse gas emissions from vegetation fires are therefore urgently needed, for international climate regulations such as the Kyoto Protocol, and for climate models.

The challenge is that current estimates of fire occurrence, their intensity, and thus the emitted amount of greenhouse gases still vary widely [3]. Also, worldwide there are very few fire models that are able to predict global fire activity [4]. These models have only been validated locally against few observations. No use has so far been made of atmospheric carbon dioxide measurements, or of global-scale satellite-derived fire and burned area observations. The student will use the most advanced methodology available in this field – assimilation of observations using a variational approach – to estimate parameter values and resulting carbon fluxes complete with uncertainties. The student will develop a method for assimilating satellite-derived remote sensing products, in addition to the existing assimilation of carbon dioxide observations in the free atmosphere.

The student's work will build on the existing Carbon Cycle Data Assimilation System (CCDAS, for further information see www.ccdas.org and [5]). CCDAS is a modelling tool that uses atmospheric CO2 concentration observations and remotely sensed vegetation activity to constrain process parameters in the terrestrial ecosystem model BETHY [6]. The inferred parameters (some spatially explicit, some global) and their uncertainty estimates are carried forward within the system to quantities of interest, such as terrestrial carbon fluxes for past, present, or future periods. CCDAS is currently the only tool of its kind that is able to quantify terrestrial carbon fluxes complete with error bars fully consistent with the major global-scale observations. BETHY represents the processes of photosynthesis, plant and soil respiration but, currently, does not include a prognostic fire model.

The student will work with the QUEST (quest.bris.ac.uk) team on a project that will improve the understanding of the contribution of fire events to seasonal and interannual fluctuations in the global carbon cycle. Good numerical skills and knowledge of at least one computer programming language, as well as interest in climate change and terrestrial ecology, are required. The project, once finished, will be of particular interest to climate change institutions (government agencies, NGOs), but is also important basic science. The modules and insights derived from this project can be applied to the newest generation of global climate models to improve predictions of the future climate.



References

  1. Bond, W. J., F. I. Woodward and G. F. Midgley, 2005, The global distribution of ecosystems in a world without fire, New Phytologist, 165, 525-538.
  2. Prentice, I. C., G. D. Farquhar, M. J. R. Fasham, et al., 2001, The Carbon Cycle and Atmospheric Carbon Dioxide, in Climate Change 2001: The Scientific Basis, eds. Houghton, J. T., et al. Cambridge Univ. Press, Cambridge, U.K., 183-237
  3. Langenfelds, R. L., R. J. Francey, B. C. Pak, L. P. Steele, J. Lloyd, C. M. Trudinger, and C. E. Allison, 2002, Interannual growth rate variations of atmospheric CO2 and its &948;13C, H2, CH4, and CO between 1992 and 1999 linked to biomass burning, Global Biogeochemical Cycles 16(3), doi:10.1029/2001GB001466.
  4. Thonicke, K., S. Venevsky, S. Sitch, W. Cramer, 2001, The role of fire disturbance for global vegetation dynamics: coupling fire to a Dynamic Global Vegetation Model, Glob. Ecol. and Biogeogr. 10, 661-677.
  5. Rayner, P., M. Scholze, W. Knorr, T. Kaminski, R. Giering and H. Widmann, 2005, Two decades of terrestrial carbon fluxes from a Carbon Cycle Data Assimilation System (CCDAS), Global Biogeochemical Cycles 19, doi:10.1029/2004GB002,254.
  6. Knorr, W., 2000, Annual and interannual CO2 exchanges of the terrestrial biosphere: process based simulations and uncertainties, Global Ecology and Biogeography 9, 225-252.
Last updated: 2/11/11