The Spatial Distribution and Temporal Drivers of Changing Global Fire Regimes: A Coupled Socio-Ecological Modeling Approach

Abstract

The limited capacity of fire-enabled vegetation models to represent human influences on fire regimes is a fundamental challenge in fire science. This limitation places a major constraint on our capacity to understand how vegetation fire may change under future scenarios of climate change and socio-economic development. Here, we address this challenge by presenting a novel integration of two process-based models. The first is the Wildfire Human Agency Model (WHAM!), which draws on agent-based approaches to represent anthropogenic fire use and management. The second is JULES-INFERNO, a fire-enabled dynamic global vegetation model, which takes a physically grounded approach to the representation of vegetation-fire dynamics. The combined model enables a coupled socio-ecological simulation of historical burned area. We calibrate the combined model using GFED5 burned area data and perform an independent evaluation using MODIS-based fire radiative power observations. Results suggest that as much as half of all global burned area is generated by managed anthropogenic fires—typically small fires that are lit for, and then spread according to, land user objectives. Furthermore, we demonstrate that including representation of managed anthropogenic fires in a coupled socio-ecological simulation improves understanding of the drivers of unmanaged wildfires. For example, we show how vegetation flammability and landscape fragmentation control inter-annual variability and longer-term change in unmanaged fires. Overall, findings presented here indicate that both socio-economic and climate change will be vital in determining the future trajectory of fire on Earth.