IMPACT pathways – a bottom-up modelling framework to guide sustainable growth and avoid carbon lock-in of cities

Increasing urbanization puts pressure on cities to prioritize sustainable growth and avoid carbon lock-in. Available modelling frameworks fall acutely short of guiding such pivotal decision-making at the local level. Financial incentives, behavioural interventions, and mandates drive sustainable technology adoption, while land-use zoning plays a critical role in carbon emissions from the built environment. Researchers typically evaluate the impacts of policies top down, on a national scale, or else post-hoc on developments vis-à-vis different polices in the past. Such analyses cannot forecast emission pathways for specific cities, and hence cannot serve as input to local policymakers. Here, we present IMPACT pathways, from a bottom-up model with residence level granularity, that integrate technology adoption policies with zoning policies, climate change, and grid decarbonization scenarios. With the city at the heart of our analysis, we identify an emission Premium for Sprawl and show that adverse policy combinations exist that can lead to rebounding emissions over time.