Global Pyrogeography: the Current and Future Distribution of Wildfire

TLDR

Climate change is expected to shift the geographic distribution of wildfire, yet how future climate change will alter global wildfire activity remains largely unknown. The study aims to quantify potential changes in global wildfire by modeling the relationship between fire activity and environmental drivers such as resources to burn, climate, human influence, and lightning. Statistical models were built at 100‑km resolution over a decade and then applied to future climate scenarios from a global climate model to project regional hotspots of fire probability. The models show that resources to burn and climate jointly determine fire‑prone regions, that regional increases in fire probability can be offset by decreases elsewhere, yet substantial invasion and retreat of fire are projected, underscoring the need to incorporate fire dynamics into global vegetation‑climate change research and conservation planning.

Abstract

Climate change is expected to alter the geographic distribution of wildfire, a complex abiotic process that responds to a variety of spatial and environmental gradients. How future climate change may alter global wildfire activity, however, is still largely unknown. As a first step to quantifying potential change in global wildfire, we present a multivariate quantification of environmental drivers for the observed, current distribution of vegetation fires using statistical models of the relationship between fire activity and resources to burn, climate conditions, human influence, and lightning flash rates at a coarse spatiotemporal resolution (100 km, over one decade). We then demonstrate how these statistical models can be used to project future changes in global fire patterns, highlighting regional hotspots of change in fire probabilities under future climate conditions as simulated by a global climate model. Based on current conditions, our results illustrate how the availability of resources to burn and climate conditions conducive to combustion jointly determine why some parts of the world are fire-prone and others are fire-free. In contrast to any expectation that global warming should necessarily result in more fire, we find that regional increases in fire probabilities may be counter-balanced by decreases at other locations, due to the interplay of temperature and precipitation variables. Despite this net balance, our models predict substantial invasion and retreat of fire across large portions of the globe. These changes could have important effects on terrestrial ecosystems since alteration in fire activity may occur quite rapidly, generating ever more complex environmental challenges for species dispersing and adjusting to new climate conditions. Our findings highlight the potential for widespread impacts of climate change on wildfire, suggesting severely altered fire regimes and the need for more explicit inclusion of fire in research on global vegetation-climate change dynamics and conservation planning.