[en] The overview presents studies of the CO₂ concentration and has found that it has increased from 280 ppmv to about 360 ppmv today. This increase is caused by combustion of carbon, oil and gas as well as altered land use. The seas absorb approximately 1/3 of the CO₂ emissions from human activity during a period of 3-5 years. In addition the oceans have chemical capacity for absorbing most of the liberated CO₂ (95%) from combustion of fossil fuels. A climatic model is developed where a marine ecosystem part is incorporated in a 3-dimensional ocean circulation model. The marine module takes into account plankton, bacteria, living organisms, nitrate, ammonium salts, sinking and freely floating biological material and total inorganic carbon and alkalinity. The model results show that the Nordic Seas absorb the most atmospheric CO₂ in view of the area and the North Atlantic Ocean absorbs the most compared to the world oceans the area considered. The two main reasons are that the heat loss to the atmosphere is particularly large above the North Atlantic and the biological fixation of dissolved inorganic carbon is very high in the northern and Arctic regions. The study is basic for forecasting future climates. The influence of the increasing pollution of the environment from human activities is discussed and the model must be adjusted to altered pollution levels