The amount of carbon dioxide that the ocean can absorb without becoming highly acidic depends on the alkalinity of its surface water. This term refers to the amount of acid-binding mineral components that were previously dissolved from weathered rock and washed into the ocean. The question now is: could a targeted input of such minerals help to increase the marine carbon dioxide uptake without unbalancing the chemistry and life in the ocean? This approach does work in simple model calculations. However, field experiments are still lacking, as are realistic simulations and detailed knowledge about the consequences and risks of an increase in alkalinity. The research mission CDRmare investigates the potentials, feasibility and side effects of the various methods.