Objective Reconstruction of atmospheric carbon dioxide concentrations （pCO₂） during the Cenomanian-Turonian （C-T） has been previously limited to stage-scale temporal resolutions， which have greatly constrained its effectiveness in unveiling the extreme greenhouse climate of the C-T period and perturbations in the global carbon cycle. Methods To enhance our understanding of pCO₂ fluctuations and the paleoclimatic response during the C-T "greenhouse climate，" this study reconstructed high-resolution atmospheric pCO₂ and mean annual precipitation （MAP） during the C-T period by analyzing the stable carbon and oxygen isotopes of paleosol carbonates from the Upper Cretaceous Nanxin Formation in the Qamdo Basin， southeastern Xizang. Results Our results reveal a gradual decline in pCO₂ during the Early Cenomanian period， followed by an increase in the Middle and Late Cenomanian stages. Moreover， we observed significant fluctuations in pCO₂ during the Early and Middle Turonian stage. These findings align with the variations in pCO₂ throughout the C-T period that have been estimated using the stomata ratio method of plant fossils and the geochemical models. In addition to the long-term pCO₂ fluctuations， the paleosols of the Nanxin Formation also documented two crucial carbon cycle perturbations during the Cenomanian period： Oceanic Anoxia Event 2 （OAE2） and Mid-Cenomanian Event （MCE）. The atmospheric pCO₂ rose by 309 μmol/mol and followed by a rapid decline of 520 μmol/mol across the initiation of MCE， accompanied by a positive shift of 1.25‰ in organic carbon isotopes （¹³C_org）. During OAE2， there were two distinct CO₂ pulses， with the maximum pCO₂ concentration coeval with the lowest ¹³C_org. The pCO₂ increased up to approximately 1 300 μmol/mol at the OAE2 boundary， followed by a reduction of approximately 17% owing to substantial organic carbon burial during OAE2. The increased concentration of CO₂ throughout the Mid-Late Cenomanian intensified the greenhouse effect and elevated atmospheric humidity， resulting in significant negative shifts in ¹³C_org that were decoupled with inorganic carbon isotopes. Our conclusion further suggests that there would be an increase of 511 mm/yr in MAP as the atmospheric pCO₂ elevated from 500 μmol/mol to 1 000 μmol/mol during the C-T period. Conclusions We assumed that the elevated atmospheric pCO₂ and climatic sensitivity during the mid-Cretaceous considerably intensified the hydrological cycle， contributing to an extreme greenhouse climate period.