Estimating risk in the Pyrocene

Wildfire risk assessments use data and modeling technologies to estimate wildfire likelihood and impact across a wide diversity of ecosystems. These assessments are used to guide investments in forest management and community hazard planning. Understanding how changing fire regimes and improvements in data and modeling impact the estimates of wildfire risk are important for guiding investments. A recent update to the national wildfire simulations presented an opportunity to examine how these changes affected the amount and pattern of simulated wildfire transmission to buildings.

Key findings and research impact: 

• The total number of buildings exposed to wildfire increased 21% in the conterminous United States using newer simulations. The increase in simulated building exposure was entirely in the eastern United States (61%) with a decline of 9% in the western United States. Differences were also dependent on fire return level (events that occur every 200 years versus every 10 years).
• In the updated simulations, simulated building exposure overestimated observed exposure by 280%, a 1.5-fold increase compared with the previous simulations. Overestimation in annual area burned was minimal in the new simulation (7% overestimation).
• In terms of spatial location, priority treatments remained largely the same across the two versions of the simulations. Known hotspots identified in both simulations are being targeted with investments by the Forest Service and partners.
• Updated simulation data suggest that substantially more area would require treatments than previously estimated to address the same level of building exposure, particularly in the eastern United States.
• Wider use of scenario analyses that reflect increased fire severity and size and extreme events can help close the gap between risk assessment products and current trends in wildfire disasters.

Photo Credit

Adapted from Figure 3 in Ager et al. 2026.

This map shows change in simulated annual building exposure at the Fireshed scale from the FSim-2020 to the FSim-2023 wildfire simulations. Warm colors (red and orange) show an increase in building exposure, while cool colors (blue) show decrease in building exposure.