Continuous measurements of CO₂ fluxes were conducted using the micrometeorological method at three locations in Sakai, Osaka, Japan, evaluating CO₂ fluxes from five landscapes: a dense urban center, a moderately urban area, a suburb, an urban park, and a rural area. Irrespective of the land cover type, all urban landscapes acted as net annual CO₂ sources, with emissions ranging from 0.5 to 4.9 kg C m⁻² yr⁻¹. The magnitude of the annual CO₂ emissions was negatively correlated with green fraction.