Abstract <p>The intra-annual course of CO₂ flux at the boundary with the atmosphere for the northern part of the Black Sea is studied on the basis of direct measurements of CO₂ concentration. The analysis of seasonal variability showed a significant flux dynamics: its values calculated from cruise data ranged from –17.7 to 14.3&#xa0;mmol m^‒2 day^‒1 (the negative and positive values indicate the atmosphere-to-water and water-to-atmosphere CO₂ flux, respectively). The intensity of the CO₂ flux on the sea surface largely depends on regional hydrometeorological conditions (a sea surface temperature and a wind speed), as well as a <i>p</i>CO₂ gradient between the sea surface and the atmosphere. Based on the field <i>p</i>CO₂ data for 2015–2024 and the average&#xa0;monthly climate wind speed and sea surface temperature, the average annual value of the CO₂ flux (–1.20 mmol m^‒2 day^‒1) was calculated, i.e., the study area absorb ~2.30 Mt CO₂ annually, while the waters of the Black Sea absorb at least 8.03 Mt CO₂.</p>