Human and Natural Drivers of Wildfires in the Basque Country: Causes and Motivations (1995–2022)

Understanding the drivers of wildfire ignition is essential for improving predictive models and early-warning systems, particularly in regions with high human activity such as the Basque Country. While natural factors like lightning and drought contribute to fire risk, anthropogenic causes dominate, shaping both the frequency and the area burned. Detailed knowledge of human-driven ignition, motivations, and seasonal patterns is critical to link historical wildfire behavior with environmental and meteorological conditions, and to improve strategies for risk management under changing climate scenarios.

The causes and motivations behind wildfires are central to effective prevention and management strategies. In the Basque Country (CAE), human activity is the dominant driver of wildfire ignitions, accounting for more than 80% of all incidents between 1995 and 2022, while natural causes such as lightning contribute less than 2% of events. This study examines a long-term dataset of 4,054 wildfire incidents, providing a detailed characterization of ignition causes, motivations, seasonal variability, and territorial patterns. Analysis of human-caused fires reveals that negligence, including uncontrolled agricultural burns, disposal of yard waste, and mishandling of fires, is the most prevalent source, followed by deliberate ignitions, accidents, and infrastructure-related causes such as electrical lines or machinery use. Among intentional fires, 48% have unknown motivations, while identified motivations include agricultural or livestock practices, political acts, pyromania, and land-use changes.

Seasonal analysis shows that negligent fires peak during the spring and summer months, coinciding with high fire risk, whereas deliberate fires are more common in spring and winter and natural fires are strongly concentrated in summer. This pattern varies across historical territories: Araba exhibits a stronger winter intentional-fire peak, while Bizkaia and Gipuzkoa show less pronounced seasonal patterns. In terms of burned area, more than 83% of total hectares affected were caused by human activity, highlighting the disproportionate influence of anthropogenic factors on fire severity. Fires attributed to negligence account for the majority of burned area in small to medium events, while intentional fires dominate in large-scale events. Temporal trends indicate a reduction in unknown causes over recent decades, reflecting improved reporting and monitoring practices.

These facts highlight the importance of integrating anthropogenic drivers into wildfire predictive models alongside meteorological and climate variables, as historical fire data can support the calibration of statistical, machine-learning, and numerical fire-spread models, improving their ability to forecast both ignition probability and burned area. Recognizing spatial, seasonal, and motivational patterns is key to developing targeted prevention measures and early-warning systems that incorporate human behavior as a central component of wildfire risk.