Traffic, heating, industries - a great part of CO2 emissions are produced in big city regions in Europe. Emissions do not stop at city bounderies. The city region brings a new approach: It looks at functional urban areas, deals with urban sprawl and urban - regional traffic. METREX, the network of more than 60 metropolitan areas in Europe, promotes new ways of climate protection by integrating law making, spatial planning, congestion management, sustainanble transport technologies and promotion of renewable energy firms.