Estimating burn severity and carbon emissions from a historic megafire in boreal forests of China

• Published in: The Science of the total environment 2020-05, Vol.716, p.136534-136534, Article 136534
• Main Authors: Xu, Wenru, He, Hong S., Hawbaker, Todd J., Zhu, Zhiliang, Henne, Paul D.
• Format: Article
• Language: English
• Subjects: Combustion efficiency; Remote sensing; The Black Dragon fire
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2020.136534

Wildfires, especially those of large size, worsen air quality and alter the carbon cycle through combustion of large quantities of biomass and release of carbon into the atmosphere. The Black Dragon fire, which occurred in 1987 in the boreal forests of China is among the top five of such megafires ever recorded in the world. With over 30 years of accumulation of data and availability of new greenhouse gas 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 four burn severity classes and calculated combustion efficiency in terms of the biomass immediately consumed in the fire. Results of the study showed that 1.30 million hectares burned and 52% of that area burned with high severity. 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. Our study provides an important basis for carbon emission estimation and understanding the impacts of megafires. [Display omitted] •Megafires released significant amounts of carbon into the atmosphere that cannot be fully offset through forest regrowth.•Uncertainties in combustion efficiency (CE) estimate may lead to large errors in fire emission estimation.•Burn severity can be used to improve CE assessment.•Using CE based on burn severity improved the accuracy of carbon emission from megafires compared to using constant CE.•Carbon accounting should recognize the effects of megafires.