Atmospheric susceptibility to wildfire occurrence during the Last Glacial Maximum and mid-Holocene

Based on coupled climate model simulations the impact of anomalous climate forcing on the environmental vulnerability to wildfire occurrence is analyzed. The investigation applies the Haines Index (HI), which indicates the potential for wildfire growth by measuring the stability and dryness of the air. Three simulations have been analyzed: for Last Glacial Maximum (LGM), the mid-Holocene (MH) and present day (MOD) conditions. The results indicate that for present day conditions, the HI is a useful tool to identify areas with high susceptibility for fire occurrence, such as the west coast of the United States and the central part of South America. Analyses for the glacial epoch demonstrated that in respect to MOD conditions, the HI is intensified in Africa and south Asia. It is reduced, however, in Australia, the west coast of North America, Europe and in northern Asia. During the mid-Holocene, the atmospheric conditions were likely more favorable for fire occurrence over North America, sub-Saharan Africa and a large part of Eurasia and South America. In the contrary, Australia, northern Africa and the northern part of South America seem to have been less susceptible to intense fire as compared to current conditions. These findings very closely match paleofire inferences based upon charcoal analyses.