Global Pyrogeography: the Current and Future Distribution of Wildfire

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.

Driving forces of global wildfires over the past millennium and the forthcoming century

“…3) and largely agree with another estimate (22). Less agreement is found with projections based on statistical relations between present-day climate and fires (23), which may be of limited value when applied to future climate due to shifting fire regime. Changes in the hydrologic cycle [some of which are robust features of climate models (24, SI Text)] play a large role in these projected regional variations, especially because temperatures rise nearly everywhere.…”

Predictability of biomass burning in response to climate changes

“…Whether this is sufficient to offset the global increase in fire in a warmer world is unclear. Some analyses based on statistical relationships between fire and environmental conditions suggest no overall change in fire in the future [e.g., Krawchuk et al, 2009] but process-based model simulations suggest that changes in precipitation are unlikely to offset temperaturedriven increases in fire [e.g., Scholze et al, 2006b;Harrison et al, 2010;Kloster et al, 2012].…”

“…Increased fire in response to warming, especially in seasonally cold climates, is primarily explained by higher fuel loads resulting from increased vegetation productivity [Krawchuk et al, 2009] and a longer fire season [Westerling et al, 2006]. This mechanism may be enhanced by the influence of temperature changes on fire-supporting weather.…”

An Architecture for Adaptive Robust Modelling of Wildfire Behaviour under Deep Uncertainty

“…Climate change [42] modifies the spatial distribution and habitat suitability of several plant species [5,43]. Along with pest outbreaks, this may alter vegetation response to fire (e.g.…”