This topic evaluates the balance at national, regional, and global levels by individually estimating emissions and absorption of each gas at the surface and aggregating them. While Topics 1 and 2 derive surface emissions and absorption starting from atmospheric observational data (called 'top-down' because they move from top to bottom), Topic 3 starts from the ground (called 'bottom-up' because it moves from bottom to top). The characteristic of the bottom-up approach is to show spatial distribution and emission breakdowns that are difficult to see with top-down approaches by collecting detailed and highly accurate information. It consists of three sub-themes: (1) evaluation based on models dealing with natural emissions/absorption and anthropogenic emission data (inventories) (University of Tokyo), (2) detection of surface emissions and their fluctuations using satellite observation data (Chiba University), and (3) observation and model evaluation of CO₂ and CH₄ emissions/absorption in forest soils (Forestry and Forest Products Research Institute).