A Study on Carbon Storage Loss and Economic Cost Estimation Caused by a Megafire

Background In March 2025, a megafire in Uiseong burned approximately 99,490 ha of forest across five counties in Gyeongsangbuk-do, becoming the largest wildfire on record in South Korea. This study develops a rapid, spatially explicit assessment framework combining the Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) carbon model and remote sensing to quantify the immediate impact of this extreme disturbance on forest carbon storage and its subsequent economic implications. We first estimated pre-fire aboveground carbon stocks using the InVEST model and classified wildfire severity using satellite image-based RdNBR (Relative differenced Normalized Burn Ratio) indices. Unlike the uniform efficiency factor used in the national inventory, we applied two burn-severity-dependent residual fraction scenarios to estimate post-fire carbon stocks and losses, reflecting the spatial variation in fire impact. Results Pre-fire aboveground carbon stock was estimated at 18.6 MtC. Depending on the retention scenario, the aboveground carbon loss ranged from 3.85 to 5.66 MtC, representing a substantial reduction of 21–30% of the pre-fire stock, corresponding to an average loss of $142–209 tCO2/ha over the burned area. Converting this loss (14.1–20.7 MtCO₂) using the average Korean Emissions Trading Scheme (K-ETS) allowance price (8,793 KRW/tCO2), the economic cost of lost carbon assets was estimated at 124–182 billion KRW. These carbon losses are equivalent to 37–55% of Korea's annual LULUCF net removals reported in 2022, suggesting that a single megafire can significantly compromise national carbon neutrality goals. Conclusion This study demonstrates the efficiency of the remote sensing–InVEST approach for rapidly estimating the magnitude and policy-relevant economic value of carbon loss. The results underscore the need to incorporate wildfire risk and disturbance accounting into the national GHG inventory and inform risk-informed restoration priorities and carbon policy design under the Framework Act on Carbon Neutrality.