Sensitivity of global wildfire occurrences to various factors in the context of global change

The occurrence of wildfires is very sensitive to fire meteorology, vegetation type and coverage. We investigate the potential impacts of global change (including changes in climate, land use/land cover, and population density) on wildfire frequencies over the period of 2000–2050. We account for the impacts associated with the changes in fire meteorology (such as temperature, precipitation, and relative humidity), vegetation density, as well as lightning and anthropogenic ignitions. Fire frequencies under the 2050 conditions are projected to increase by approximately 27% globally relative to the 2000 levels. 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 total fires by around 19%. Modest increases (∼4%) in fire frequency at tropical regions are calculated in response to climate-driven changes in lightning activities, relative to the present-day levels. Changes in land cover by 2050 driven by climate change and increasing CO 2 fertilization are expected to increase the global wildfire occurrences by 15% relative to the 2000 conditions while the 2000–2050 anthropogenic land use changes show little effects on global wildfire frequency. The 2000–2050 changes in global population are projected to reduce the total wildfires by about 7%. In general, changes in future fire meteorology plays the most important role in enhancing the future global wildfires, followed by land cover, lightning activities and land use while changes in population density exhibits the opposite effects during the period of 2000–2050.