With cities contributing upwards of 75 per cent of global carbon emissions, urban design is increasingly important when planning for climate change. This discussion examines the creative urban design solutions coming out of the world’s cities. Saskia Sassen is Robert S Lynd Professor of Sociology at Columbia University. Richard Sennett is professor of sociology at LSE and NYU. Jonathon Porritt is the chair of the sustainable development commission and founder and director of Forum for the Future.