Over half the world’s population lives in urban areas, which provide economic opportunity, the potential for increased efficiency and improvements in standard of living. They are also under stress from rapid growth and the effects of climate change. Can innovations in green infrastructure – using trees and other plants on roofs and along sidewalks to control storm runoff, for instance -- help cities balance growth with sustainability imperatives? How will urban areas become stronger and more resilient while adapting to climate change? How can the study of environment’s impacts on infectious diseases or the principles of sustainable peace help cities ensure the health and safety of their citizens?