Seeding of clouds to increase reflectivity - Concepts, potentials and risks: The systematic brightening of low clouds as a measure of solar radiation management against proceeding global warming has been under discussion since the early 1990s. In principle, the reflectivity of suitable clouds could be increased by seeding them with additional condensation nuclei. The most suitable clouds are likely marine stratocumulus clouds. A corresponding effect was observed in ship tracks. Available model studies on the effectiveness and side effects of cloud brightening do not yet show clear results. Questions regarding the areas of application, the technolo­gical implementation, and the risks are still unresolved.