Assessment of the Impacts of Different Carbon Sources and Sinks on Atmospheric CO2 Concentrations Based on the GEOS-Chem Model

Global CO2 concentration has become a key driver of climate change, influenced by both anthropogenic emissions and natural carbon cycles. However, due to the spatiotemporal heterogeneity of carbon sources and sinks, estimating CO2 flux remains highly uncertain. Accurately quantifying the contribution of various carbon sources and sinks to atmospheric CO2 concentration is essential for understanding the carbon cycle and global carbon balance. This study utilizes the GEOS-Chem model, driven by MERRA2 meteorological data and emission inventory data, to simulate monthly global CO2 concentrations from 2006 to 2010. The “Inventory switching and replacing” method was applied to assess the contributions of eight major CO2 sources and sinks: fossil fuel combustion, biomass burning, biosphere balance, net land exchange, aviation, shipping, ocean exchange, and chemical sources. The results show that global CO2 concentration exhibits a spatial pattern with higher concentrations in the Northern Hemisphere and land areas, with East Asia, Southeast Asia, and Eastern North America being high-concentration regions. The global average CO2 concentration increased by 1.8 ppm/year from 2006 to 2010, with China’s eastern region experiencing the highest growth rate of 3.0 ppm/year. Fossil fuel combustion is identified as the largest CO2 emission source, followed by biomass burning, while oceans and land serve as significant CO2 sinks. The impact of carbon flux on atmospheric CO2 concentration is closely related to the spatial distribution and magnitude of emissions.