“In an increasingly urbanized world, global sustainability in the context of a changing climate will depend on achieving sustainable and climate resilient cities,” the Intergovernmental Panel on Climate Change (IPCC) says today (28 March 2012). Cities are increasingly experiencing the disruptive and costly impacts of changes in the frequency and/or severity of weather extremes. Responding to the trends, city officials are engaging their citizens in efforts to build more resilient, better prepared and more sustainable communities. On Saturday the City of Tucson, Arizona, is bringing its citizens together to discuss the challenges climate change poses the city and the opportunities to respond. At the event, WWF will launch its Earth Hour City Challenge to encourage cities across the country to similarly engage their citizens around climate impacts and preparedness.