Shifting social-ecological fire regimes explain increasing structure loss from Western wildfires

Area of Science:

• Wildfire science
• Ecology
• Sociology

Background:

• Wildfire crisis in the western US causes significant structure loss.
• Understanding recent trends and causes of structure loss is critical.

Purpose of the Study:

• Document trends in wildfire-related structure loss in the western US from 1999-2020.
• Identify key drivers of increased structure loss, including ignition sources and development patterns.
• Inform regionally appropriate mitigation and adaptation strategies.

Main Methods:

• Analyzed trends in structure loss and area burned across the western US from 1999-2020.
• Compared structure loss rates between human-related and lightning-ignited wildfires.
• Investigated the relationship between structure loss, ignition sources, and development in fire-prone areas.

Main Results:

• West-wide structure loss increased by 246% between 1999-2009 and 2010-2020.
• Wildfires became 160% more destructive per unit area burned.
• Human-related ignitions accounted for 76% of structure loss and were 10 times more destructive per area burned than lightning fires.
• Structure loss correlated with human-caused ignitions and development in flammable vegetation, exacerbated by increased fuel aridity.

Conclusions:

• Wildfire regimes are social-ecological phenomena, influenced by human activities and development.
• Reducing human-caused ignitions and adapting building practices are crucial for mitigating future wildfire disasters.
• Regionally tailored strategies are needed to address diverse fire regimes and reduce structure loss.