Fire and Climate

Global pygrogeography examines the spatial distribution of wildfire (vegetation fires) across the planet. Fires are phenomena generated through the spatial-temporal coincidence of three constraining factors: biomass resources to burn, atmospheric conditions conducive to the combustion of fuels (fire weather, seasonality), and ignition agents (human, lightning, volcano). Climate contributes to variability in all three factors, e.g., through fire weather, the distribution and structure of biomass resources, storms and lightning activity, and through human activity. Fire and climate have varied together over Earth’s history, and while our ability to quantify and understand observed variability in complex fire-climate relationships is relatively well developed in some places and times, our understanding of global fire is still at a youthful phase. Yet due to tight fire-climate coupling, fire is likely to respond quickly to global warming, so it is urgent that we pick up the pace on studies and integration of fire into global change research. The few existing global studies of fire and climate change suggest the interplay of moisture and temperature could lead to relatively rapid increases in fire activity in some regions of the world, while others could experience decreases. All the while, human activity will continue to contribute to fire, for example, while climate contributes to variability in deforestation fires in the tropics, these fires are largely human-driven. These changes in fire activity have the capacity to alter ecosystem state, modify atmospheric chemistry, generate climate feedbacks, and affect socio-economic conditions. Here, we will discuss climate-fire relationships, how climate change may alter global fire activity, and use examples from recent advances in statistical modeling of biophysical constraints on global fire to understand potential future fire patterns and uncertainties.