Wildfire

Wildfire

A wildfire spreads from nearby vegetation and reaches the site. The fire damages or destroys the asset, and the site stops while it is rebuilt. The risk depends on two things together: how often the land around burns, and how intense a fire the local weather can carry. Wildfire prices both Property damage (% of asset value) and Business interruption (% of annual revenue).

What the map shows

• Today: three rasters, in reading order. First the wildfire annualised loss, the two inputs already multiplied, for an asset at the edge of fuel (sheet). Then the observed burned-area fraction, which does not move. Then the design Fire Weather Index (FWI).
• Projected: the annualised loss and the FWI each have a band per scenario at 2035, 2050 and 2080. The high emissions setting at 2035 shows the current band, because the current band already is the 2030-2040 window. Only the fire weather moves with the horizon; the burned-area frequency is an observed climatology and stays fixed.

How the loss is computed

The engine reads, at the site's point, the observed annual burn probability and the design FWI. The Van Wagner (1987) relation turns the FWI into a fireline intensity, and the FireLossRate function turns that intensity into a share of asset value lost, reduced with the site's distance to fuel (a Darwin tier per site type). The annual loss is the burn probability times that loss. Business interruption is a loss-of-use relation on the same loss ratio. Wildfire is tagged Built. See Damage functions: Wildfire and Climate risks.

Sources

• Frequency: Copernicus CDS satellite-fire-burned-area, ESA CCI Fire_cci FireCCI51 (MODIS) and C3S OLCI (Sentinel-3), mean 2014-2023. Fire_cci: ESA CCI data policy, free use with acknowledgement of "the ESA Climate Change Initiative and the Fire CCI project". C3S OLCI: Licence not confirmed.
• Severity: design FWI computed from NASA NEX-GDDP-CMIP6 daily downscaled climate (yearly 98th percentile, GFDL-ESM4 and MPI-ESM1-2-HR ensemble mean, 0.25° source grid). CC0 1.0.
• Damage curve: FireLossRate (Nicoletta et al. 2023; Abo El Ezz et al. 2022), on the Van Wagner (1987) FWI to intensity relation.
• Coastline: Natural Earth 10 m land polygons. Public domain.

Limits

• FireLossRate counts the share of exposed residential buildings that burned. None of its sources is industrial, agricultural or savanna.
• The intensity is that of the fire danger system's standard reference fuel, not the site's own vegetation. The curve is zero below FWI 10.
• The annual burn probability is capped, so grass savannas that burn almost every year do not read as near-total yearly loss.
• Trajectories understate the growth of fire frequency: the frequency term is fixed and only the fire weather moves.