When ecological, social, or economic structures make the existing system unsustainable, it may be necessary to fundamentally change the nature of the system – to transform it. Considering the urgency of global climate change and other environmental, social and economic pressures, it is presumed that the current urban system is close to crossing several thresholds of sustainability and that a new system – the post-carbon city – is necessary to prevent the movement into an undesirable state from which it is difficult, if not impossible, to recover.

Within the POCACITO framework, the concept of “POST-CARBON CITIES” signifies a rupture in the carbon-dependent urban system, which has lead to high levels of anthropogenic greenhouse gases, and the establishment of new types of cities that are low-carbon as well as environmentally, socially and economically sustainable. The term post-carbon emphasises the process of transformation, a shift in paradigm, which is necessary to respond to the multiple challenges of climate change, ecosystem degradation, social equity and economic pressures. Through their adaptive capacity, post-carbon cities use the threat of climate change “as an opportunity to reduce vulnerability as they restructure human–ecological and human–human relationships toward ecosystem health and a clean energy economy.”[1]