The general scientific objectives of SESAME IP, supported by the European Commission, are to assess and predict changes in the Mediterranean and Black Sea ecosystems as well as changes in the ability of these ecosystems to provide goods and services. The Mediterranean and Black Sea will be approached as a coupled climatic/ecosystem entity, with links and feedbacks to the world ocean. The assessment of ecosystem changes will be based on the identification of the major regime shifts in ecosystems that occurred during the last 50 years. Mathematical models, validated and upgraded using existing and new observations, will be used to predict ecosystem responses to changes in climate and anthropogenic forcings during the next five decades. The new data will be gathered during multidisciplinary, multiship oceanographic cruises in the Mediterranean and Black Sea. These will provide an overall picture of the Mediterranean and Black Sea that does not yet exist as well as essential datasets for model validation. SESAME will also study the effect of the ecosystem variability on key goods and services with high societal importance like tourism, fisheries, ecosystem stability through conservation of biodiversity and mitigation of climate change through carbon sequestration in water and sediments. The innovative character of SESAME is reflected in the close merging of economic and natural sciences to study the changes in the western and eastern Mediterranean and the Black Sea within the period from 50 years in the past to 50 years in the future. SESAME will create a platform for disseminating the research results to all levels of society. It will stimulate and strengthen international cooperation in the Mediterranean and Black Sea regions through the participation of research organizations from Member States, Associated States, Associated Candidate countries, non-EU Mediterranean and NIS countries as well as international organizations.