Widening concepts – a cities approach to planetary boundaries

Following efforts to dene and quantify safe planetary biophysical operating limits in areas such as climate change, biodiversity and water use, this chapter develops an approach to monitor boundaries from a city’s perspective. Biophysical boundaries are largely a local presentation of Rockstrom et al.’s (2009) proposed planetary systems boundaries (updated in 2015 by Steffen et al.). Socio-economic boundaries or targets are largely derived from the Sustainable Development Goals (SDGs; previously the Millennium Development Goals). The approach is trialled for Dakar, Mumbai, São Paulo, Shanghai and Toronto.