Global carbon emission accounting: national-level assessment of wildfire CO2 emission – a case study of China

Abstract. Wildfires release large amounts of greenhouse gases into the atmosphere, exacerbating climate change and causing severe impacts on air quality and human health. Including carbon dioxide (CO₂) emissions from wildfires in international assessments and national emission reduction responsibilities is crucial for global carbon reduction and environmental governance. In this study, based on a bottom-up approach and using satellite data, combined with emission factor and aboveground biomass data for different vegetation cover types (forest, shrub, grassland, cropland), the dynamic changes in CO₂ emissions from wildfires in China from 2001 to 2022 were analyzed. The results showed that between 2001 and 2022, the total CO₂ emissions from wildfires in China were 693.7 Tg (1 Tg = 10¹² g), with an annual average of 31.5 Tg. The CO₂ emissions from cropland and forest fires were relatively high, accounting for 46 % and 32 %, respectively. The yearly variation in CO₂ emissions from forest and shrub fires showed a significant downward trend, while emissions from grassland fires remained relatively stable. In contrast, the CO₂ emissions from cropland fires showed a clear upward trend. High CO₂ emissions from wildfires were mainly concentrated in the eastern regions of Heilongjiang and Inner Mongolia Provinces in China, accounting for 44 % of the total annual emissions. Various factors such as daily cumulative sunshine hours (Spearman’s correlation coefficient, forest: -0.41, shrub:0.25; p < 0.001) and the normalized difference vegetation index (NDVI; Spearman’s correlation coefficient, forest: -0.35, shrub: 0.37; p < 0.001), influenced CO₂ emissions from forest and shrub fires. Moreover, temperature (Spearman’s correlation coefficient, -0.45, p < 0.001) primarily affected CO₂ emissions from grassland fires. The CO₂ emissions from cropland fires negatively correlated with the gross domestic product (GDP) (Spearman’s correlation coefficient, -0.52, p < 0.001) and population density (Spearman’s correlation coefficient, -0.51, p < 0.001). China's policy management has been crucial in reducing CO₂ emissions from wildfires. By accurately assessing CO₂ emissions from wildfires, governments worldwide can better set CO₂ reduction targets, take corresponding measures, and contribute to the global response to climate change.