We are already at 1º Celsius warming beyond pre-industrial averages. Limiting global warming to 1.5° Celsius (2.7° Fahrenheit)—beyond which scientists expect more significant damage to global ecosystems—requires "rapid and far-reaching transitions" in energy systems, land use, industry and urban infrastructure. In short, we need to live and build differently.

Those of us focused on cities know this is true. The trajectory for major trends needs to change significantly in urban areas to reach the targets agreed to by the world's governments in the Paris Agreement, Sustainable Development Goals and New Urban Agenda. We need not just nudges and tweaks, but transformation on a massive scale, starting now.