Purpose – The purpose of this paper is to present some basic conceptual aspects and empiric examples of urban mitigation and adaptation to climate change, of greening urban development, as there is strong need for further research and education on these issues. Design/methodology/approach – Starting with a review of the 4th IPCC report and the Stern Review, a strategy is developed on how to make cities main actors in fighting climate change. First examples of successful urban greening are presented. Findings – Cities are main drivers of climate change, and they are driven by climate change. Therefore, there is a strong need for “greening” urban development, i.e. for both mitigation and adaptation activities. Practical implications – Mitigation requires the reduction (more or less drastically) of urban energy and material flows. Adaptation requires restructure (more or less radically) of the established urban stocks. Originality/value – Until recently, cities and urban areas have not been in the focus of climate change research and climate policy. The paper shows the need for change of both theory and practice.