Population growth, urbanization, and future wildfire risks

Leiwen Jiang, Shanghai University

Wildfires, as a component of terrestrial ecosystem ecology and risk factor in human societies, are affected by climatic conditions, atmospheric CO2 concentration, and population intervention. Studies of historical burned areas show that increasing population size and density significantly contributed to a secular decline in wildfire activity. While future wildfire prevalence is commonly believed to increase in a warmer and in many places drier world, increasing CO2 concentration and related in the prevalence of shrubs vs. grasses tend to lower wildfires predictions. More importantly, uncertainties in future population growth and spatial distribution under different urbanization trajectories may lead to different wildfires trends. Adopting the semi-empirical fire model SIMFIRE and combining it with the global dynamic vegetation model LPJ-GUESS, this paper explores impacts of population growth and urbanization on future wildfire risks. It reveals that a smaller population concentrated in urban areas will lead to higher wildfire prevalence, and human exposure to wildfires is driven mainly by sprawling human settlements to fire prone areas.