Rethinking urban sustainability: consumption-based emissions through the lens of planetary urbanization

Urban areas, which are responsible for the majority of global greenhouse gas emissions, play an important role in climate change mitigation. Although many cities are setting ambitious targets, these typically focus on production-based emissions within municipal boundaries, leaving consumption-based emissions — those embedded in goods and services often produced elsewhere — largely unaddressed. Meanwhile, the theoretical concept of planetary urbanization highlights how urban processes extend well beyond traditional city limits, shaping global resource flows, infrastructure networks, and ecosystems. Cities are beginning to recognize the importance of tracking and managing consumption-based emissions, yet most use such metrics only as informational tools rather than formal targets. Various strategies — ranging from degrowth proposals that advocate reduced overall consumption to circular economy initiatives emphasizing reuse and recycling — offer pathways for lowering urban footprints. However, the efficacy and equity of these approaches require more research, and existing indicators often overlook complex transboundary impacts. Despite these challenges, cities are uniquely positioned to lead the shift toward more sustainable lifestyles, given their density-driven advantages in infrastructure provision and innovation. By leveraging these strengths, experimenting with policy interventions, and rigorously measuring outcomes, urban areas have the potential to catalyze transformative change. Ultimately, a deeper acknowledgment of planetary interconnectedness, combined with expanded data collection and inclusive decision-making, is essential for cities to fulfill their potential as engines of global sustainability.