Reconciling scales for modeling the effects of climate change on wildfire

Uma Shankar1, Don McKenzie2, Jared Bowden3, Kevin Talgo4, Dr. Limei Ran, PhD1, Bok Baek1, Zachariah Adelman4, Aijun Xiu5, Mohammad Omary4, Elizabeth A Adams4 and Dongmei Yang4, (1)University of North Carolina at Chapel Hill, Chapel Hill, United States, (2)US Forest Service, Pacific Wildland Fire Sciences, Seattle, United States, (3)North Carolina State University, Applied Ecology, Raleigh, NC, United States, (4)University of North Carolina at Chapel Hill, Chapel Hill, NC, United States, (5)Key Laboratory of Wetland Ecology and Environment, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun, China

Contact First Author: Uma Shankar; shankar.uma@epa.gov

Previously Published Material: A review article co-authored by the first and second authors was published under the title "Smoke consequences of wildfire regimes driven by climate change" in the AGU online journal Earth's Future (McKenzie et al., Earth's Future, 2, 35-59, 2014). It describes the issues of scale associated with earth system models that are used to study the effects of climate change on wildfires. However it did not present the results of the modeling study described in this submission; the study began after that publication.

Abstract ID#: 35814

 

English Abstract:
Smoke from wildfires has adverse biological and social consequences, and various lines of evidence suggest that smoke from wildfires in the future may be more intense and widespread, demanding that methods be developed to address its effects on people, ecosystems, and the atmosphere. Projecting smoke consequences of future wildfires requires a multidisciplinary approach that involves reconciling complex physical and biological processes at widely different scales in space and time. We review the most difficult scaling issues, which include: (1) reconciling regional-scale atmospheric processes with fine-scale fire-spread dynamics and variation in fuel loadings, (2) translating contagious disturbance (fire) across landscapes in varying topography into estimates of regional smoke transport, and (3) identifying the feasibility of coupled modeling that incorporates important feedbacks vs. a simpler approach that may be less error-prone for integrating modules at different scales. We illustrate model linkages and tradeoffs with results from an ongoing study of climate change, wildfire, and air quality in the Southeastern US. This study dynamically downscales general circulation model (GCM) output to model the regional climate, and includes vegetation from coupling land cover to the GCMs; empirical fuel loadings at fine scales, projected into the 2040s with a delta method; a stochastic coarse-scale fire generator, and regional air quality assessments of the fire emission impacts with the Community Multiscale Air Quality (CMAQ) model. There are considerable challenges in representing future climatic variability important for fire while keeping computations feasible, but also in two efforts associated explicitly with reconciling processes across scales. First, how can coarse-scale carbon pools generated by the global model be translated into the fine-scale fuel characteristics that are critical for modeling fire? Second, how can fine-scale variation in fire activity associated with the spatial patterns of topography and vegetation (fuels) be aggregated meaningfully to produce regional projections?
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