Is ‘sustainable’ enough for the future of cities? Certainly ‘smart’ isn’t. If we can agree that climate catastrophe and the sixth great extinction (in and of the natural world) are the products of and existential risks to humankind, what to do? Add social injustice, a growing world population and economic growth averaging 3% each year cumulatively, we’re f*****. We need something truly remarkable. So, we worked out some thoughts about what that might mean, enlisted Grosvenor as benefactors, and ran a programme at Pembroke College Cambridge.