OT-Med (Objectif Terre - Bassin Méditerranéen) is a “Laboratoire d'excellence” (LABEX) selected by the French program Investissements d'Avenir. It brings together 10 research laboratories and 1 research federation specialised in different fields: environmental sciences, geosciences, ecology, agronomy, law, economics and social sciences. Our objective is to coordinate and stimulate interdisciplinary research on global change and natural hazards in the Mediterranean basin and semi-arid regions of Sahel. Specific objectives are to understand the impact of climate and socio-economic changes on ecosystems with a focus on the ecosystem services, in particular related to biodiversity, soils, agriculture, forestry, marine biogeochemistry and food-web interactions. Other themes are 1) analysing human-environment interactions, perception of hazards, adaptation to climate change and its mitigation; 2) modelling decision-making in the context of risks and comparing the functioning of international environmental regimes for climate and biodiversity; 3) using past variations of climate and ecosystems to understand long term processes. To achieve these objectives, OT-Med is developing integrated models linking the climate system to the ecosystems and the society. OT-Med supports the development and the interactions between observatory systems and databases to answer to questions related to the interaction between greenhouse gases, climatic changes and large cities. OT-Med wants to identify and evaluate innovative strategies to help decision-makers in elaborating public policies and enterprises in treating environmental questions (through data, models and technologies).