Abstract
Abstract. Vegetation fires are a major driver of ecosystem dynamics and greenhouse gas emissions. Anticipating potential changes in fire activity and their impacts relies first on a realistic model of fire activity (e.g., fire incidence and interannual variability) and second on a model accounting for fire impacts (e.g., mortality and emissions). In this paper, we focus on our understanding of fire activity and describe a new fire model, HESFIRE (Human–Earth System FIRE), which integrates the influence of weather, vegetation characteristics, and human activities on fires in a stand-alone framework. It was developed with a particular emphasis on allowing fires to spread over consecutive days given their major contribution to burned areas in many ecosystems. A subset of the model parameters was calibrated through an optimization procedure using observation data to enhance our knowledge of regional drivers of fire activity and improve the performance of the model on a global scale. Modeled fire activity showed reasonable agreement with observations of burned area, fire seasonality, and interannual variability in many regions, including for spatial and temporal domains not included in the optimization procedure. Significant discrepancies are investigated, most notably regarding fires in boreal regions and in xeric ecosystems and also fire size distribution. The sensitivity of fire activity to model parameters is analyzed to explore the dominance of specific drivers across regions and ecosystems. The characteristics of HESFIRE and the outcome of its evaluation provide insights into the influence of anthropogenic activities and weather, and their interactions, on fire activity.
Highlights
The human population has more than doubled in the past 50 years, expanding the scale and diversity of changes in the Earth system due to anthropogenic activity
This paper describes the development of the HESFIRE model (Human–Earth System FIRE), aimed at improving our understanding of current fire activity and our capacity to anticipate its evolution with future environmental and societal changes
The parameters inferred by the optimization procedure are consistent with our current understanding of fire drivers, and provide a quantitative estimate on otherwise poorly constrained relationships
Summary
The human population has more than doubled in the past 50 years, expanding the scale and diversity of changes in the Earth system due to anthropogenic activity. Interactions between human and natural systems are complex, yet observational data, field experiments, and various types of models continue to elucidate key linkages between climate variability, ecosystem function, and anthropogenic activities. This knowledge is essential for anticipating potential changes under future conditions and to design adaptation or mitigation strategies that promote the sustainability of the coupled human–Earth system. One of these interactive processes linking human activities and natural ecosystems is fire (Bowman et al, 2009).
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