Planning for Urban Sustainability: A Complex Adaptive System Analyses of the Lisbon Green Infrastructure

The 2030 Agenda for Sustainable Development and the Paris Agreement call for a transformation in societies, with interdependent goals, and a complex coupling between social, technical, and ecological systems. Cities are essential drivers for development, innovation, experimentation, and change. They can be obstacles and/or drivers for achieving sustainability. Nevertheless, current models of urban governance may not be able to address 21st century challenges. They are highly dependent on predictability, address problems linearly, and assume that viable solutions can be prescribed to meet established goals when, in reality, society is complex, dynamic, and constantly evolving. An interconnected approach between complex system thinking and planning, can present new perspectives for a sustainable transition. Through adequate governance of green infrastructure in cities, urban systems can benefit through the improvement of citizens health, wellbeing, conservation of biodiversity, supply of ecosystem services, and strength of urban capacity for resilience and adaptation. This research explores, through the lens of complexity, how governance arrangements and institutions influenced the effective implementation of the Lisbon Green Infrastructure System (LGIS) and the role of actors involved. The analysis shows that the process of construction and implementation of the visions for the future (planning) of the actual LGIS can be explained as a complex adaptive system, shaped by negative and positive feedback loops over time. Through mapping where transformative action was originated, the actors involved, and the effects on the implementation process, can help to embrace uncertainty in urban governance.