Abstract: A comparative study on karst process-related carbon sink intensity between the two karst water systems with similar lithology but different climate and land use scenarios and with high resolution hydrological and hydrochemical automatic monitoring data is presented to show the significance of runoff in determining the carbonate weathering carbon sink intensity. The two systems are Houzhai karst water system with high ratio of soil cover in catchment area (Puding County, Guizhou Province, Southwest China), and Tsanfleuron glaciated and snow covered rocky karst water system in Alps, Switzerland. The results show that the annual mean concentration of HCO₃^- of Houzhai karst water systems in their discharge areas is 222 mg/L, while that of Tsanfleuron karst water system is only 131 mg/L. This indicates that the karst water systems in humid subtropics were characterized by high [HCO₃^-]However, the carbon sink intensity of the karst water system in humid subtropics (60.82 t/(km₂?a)) was almost the same as that of Tsanfleuron glaciated karst water system (59.06 t/(km₂?a)). The reason for the high carbon sink intensity in glaciated karst water system was mainly that under the global warming conditions, the glacier melts more quickly, and the effect of resulting runoff increase was much stronger than that of [HCO₃^-] decrease by dilution, so the carbon sink intensity of alpine glaciated karst water system increased instead. It also implies that the karst process-related carbon sink intensity in glaciated karst water systems will decrease if some glaciers disappear due to global warming.