An expanded framing of ecosystem services is needed for a sustainable urban future

Urban activities are an important driver of ecosystem services decline. Sustainable urbanisation necessitates anticipating and mitigating these negative socio-ecological impacts, both within and beyond city boundaries. There is a lack of scalable, dynamic models of changes to ecosystems wrought by urban processes. We developed a system dynamics model, ESTIMUM, to predict locations, types, and magnitude of changes in ecosystem services. We tested the model in Lisbon (Portugal) under four specific urban development scenarios - a base case scenario and three local sustainability-driven scenarios - to the year 2050. Our results show that urban sustainability policies focused on reducing impacts within Lisbon can be undermined by increased impacts in the extended regions that supply resources to the city. In particular, carbon sequestration from urban greening pales in comparison to growing greenhouse gases from the consumption of food, energy and construction materials. We also find that policies targeted at these extended environmental impacts can be much more effective than those with a limited focus on the urban form. For example, dietary shifts could support positive changes outside that city to increase global climate regulation by 54% compared to a mere 1% increase through intensive urban greening. This highlights the urgent need for a reframing of urban sustainability in policy and scholarly circles from city-centric focus towards an expanded multi-scalar conceptualisation of urban sustainability that accounts for urban impacts beyond the city boundaries.