Estimating carbon emissions from a historic megafire using Landsat imagery and field inventory data

Abstract:

Significant amounts of carbon are emitted to the atmosphere due to large and catastrophic fires, worsening air quality and altering the carbon cycle. The Black Dragon fire, which occurred in 1987 in the boreal forests of China is among the top 5 of such megafires ever recorded in the world. With over 30 years of accumulation of data and availability of new greenhouse gas (GHG) emission accounting methods, carbon emissions from this megafire can now be estimated with improved precision and greater spatial resolution. To do this, we combined field and remote sensing data to map 4 burn severity classes and calculated combustion efficiency in terms of the biomass immediately consumed in the fire in different burn severity classes. Results of the study showed that 1.30 million hectares burned and 52% of that area burned with high severity. The average combustion efficiency for high severity fire was 0.67, which is 1.5 to 6.5 times greater than the fixed combustion efficiency used in other studies. The emitted carbon dioxide equivalents (CO₂e), accounted for approximately 10% of total fossil fuel emissions from China in 1987, along with CO (2% - 3% of annual anthropogenic CO emissions from China) and non-methane hydrocarbons (NMHC), contributing to the atmospheric pollutants. Comparison of our results with previous emission estimates for this megafire showed improved accuracy. Our study provides an important basis for carbon emission estimation and understanding the impacts of megafires.