MACC-III is the last of the pre-operational stages in the development of the Copernicus Atmosphere Service. Its overall institutional objective is to function as the bridge between the developmental precursor projects - GEMS, PROMOTE, MACC and MACC-II- and the Atmosphere Service envisaged to form part of Copernicus Operations.MACC-III will provide continuity of the atmospheric services provided by MACC-II. Its continued provision of coherent atmospheric data and information, either directly or via value-adding downstream services, is for the benefit of European citizens and helps meet global needs as a key European contribution to the Global Climate Observing System (GCOS) and the encompassing Global Earth Observation System of Systems (GEOSS). Its services cover in particular: air quality, climate forcing, stratospheric ozone, UV radiation and solar-energy resources.MACC-III’s services are freely and openly available to users throughout Europe and in the world. MACC-III and its downstream service sector will enable European citizens at home and abroad to benefit from improved warning, advisory and general information services and from improved formulation and implementation of regulatory policy. MACC-III, together with its scientific-user sector, also helps to improve the provision of science-based information for policy-makers and for decision-making at all levels. The most significant economic benefit by far identified in the ESA-sponsored Socio-Economic Benefits Analysis of Copernicus report published in July 2006 was the long-term benefit from international policy on climate change. Long-term benefit from air quality information ranked second among all Copernicus benefits in terms of present value. Immediate benefits can be achieved through efficiency gains in relation to current policies. The estimated benefits substantially outweigh the costs of developing and operating the proposed services.