The future of our civilization will be decided in the cities. The internationally agreed Sustainable Development Goals of the United Nations and the Paris Agreement on climate change can only be achieved if we design sustainable and liveable cities across the globe.
What kind of homes should people live in? Where can they settle? How close may their neighbours encroach on them? These questions are as old as our civilization, but in the 21st century they are being asked in a new way. Because this century is characterized by a contradiction dynamic that eclipses much of our previous experience of social change: rapidly growing populations in many developing countries versus shrinking populations in some industrialized countries; the enrichment of tiny elites versus the ongoing economic marginalization of the majority; guarded luxury real estate surrounded by squalid, poor neighbourhoods in many megacities; improved access to basic supplies and services for billions of Earth dwellers, while at the same time their long-term life-support systems are being destroyed by resource looting, climate change and environmental pollution. The present report outlines the special challenges and opportunities faced in this century by cities from the perspective of the necessary transformation towards sustainability. One characteristic feature of the debate on the search for solutions is the enormous diversity of instruments and solution pathways. Consequently, there can be no blueprint for sustainable urban development.