CLIMATE, FIRE AND BIOMASS BURNING EMISSIONS AT THE LAST GLACIAL MAXIMUM

There is abundant evidence for changes in fire regimes during the Late Quaternary, associated with changes in climate, vegetation or both. Burning conditions are driven by climate and vegetation status (including fuel moisture and amount). Fire has implications for vegetation dynamics, biogeochemical cycles, atmospheric chemistry and radiative forcing. We have investigated possible global changes in fire regime using climate model simulations of the last glacial maximum (LGM) and the dynamic global vegetation model LPJ. Much work has been done on reconstructing climate and vegetation changes between LGM and present, and on the causes of milennial scale variability during the glacial, but the potential implications for changes in fire regime and atmospheric chemistry have not previously been analysed. LPJ (with its embedded fire regime model Glob-FIRM) predicts changes in fire regime as a complex consequence of changes in vegetation productivity, carbon cycling and ecosystem water balance. Emissions of reactive trace gases are computed from CO2 release using empirical emissions factors. Simulated vegetation patterns are compared with the “BIOME 6000” data set of site-based biome reconstructions for the LGM, and simulated fire regimes can be compared with sedimentary charcoal records and other indicators of past changes in fire. As a first step towards an improved understanding of ice-core records of atmospheric greenhouse gases other than CO2, we will briefly consider the potential of the simulated changes in fire regime to feed back to atmospheric composition and climate.