An observed increase in alkalinity of the East Siberian Sea during the last quarter of the XX century is the result of CO2 absorption from the atmosphere, a more intense transport of organic substances into the water due to more active erosion of ice-rich coasts related to climate warming. Destructive coastal cryogenic processes disturb the carbonate balance causing sharp rises in a partial pressure of CO2 up to 8x10-4 in inshore waters and violations of the regular relative proportions of the alkali reserve and chlorine content. However, during summer seasons, a dominating partial pressure of CO2 is much lower in waters than in the atmosphere and varies from 0.83x10-4 to 1.89x10-4 depending on physical and chemical conditions. The current climate changes have not yet affected a potential ability of the sea to absorb CO2 from the atmosphere. On the other hand, a more active erosion of the ice-rich coasts due to climate warming reduces the ability of the sea to absorb CO2, especially in coastal, cryogenically active sections of the water area
