Sensitivity of Global Wildfire Occurrences to Various Factors in the Context of Global Change

Abstract:

The occurrence of wildfires is very sensitive to fire meteorology, vegetation type and coverage. We investigate the potential impacts of climate change and land use/land cover change on global wildfires over the period of 2000-2050. We account for the impacts on wildfires associated with fire meteorology (such as temperature, precipitation, and relative humidity), vegetation density, as well as lightning and anthropogenic ignitions. For the present-day conditions, our model results successfully reproduce the spatial variability of wildfires, with highest fire counts in Africa and South America, which are generally consistent with observations. Fire counts under the 2050 conditions are projected to increase by approximately 27% globally, relative to the 2000 level. Significant increases in fire occurrence are calculated over the Amazon area, Australia and central Russia, while southeast Africa shows a large decreasing trend due to significant increases in land use and population. Changes in fire meteorology driven by 2000-2050 climate change are found to increase the global annual fire counts by around 19%. Modest increases (~ 4%) in fire counts at tropical regions are calculated in response to climate-driven changes in lightning activities associated, relative to the present-day level. Changes in land cover by 2050 driven by climate change and increasing CO₂ fertilization are expected to increase the global wildfire counts by 15% relative to the 2000 condition while the 2000-2050 anthropogenic land use changes show little effects on future wildfire. The 2000-2050 increases in global population are projected to reduce the total wildfires by about 7%.