Climate change mobilizes urban PAHs into systemic environmental risks (SERisks)

Managing urban sustainability in the Anthropocene requires addressing pollution legacies that are increasingly destabilized by climate change. Polycyclic aromatic hydrocarbons (PAHs), historically treated as persistent and relatively stable in soils, are now recognized as dynamic reservoirs that exchange with the atmosphere, water, dust, and biota. A synthesis of more than 190 studies shows that extreme climate events such as heatwaves, droughts, and intense rainfall disrupt soil-pollutant equilibria, triggering nonlinear multimedia transport, climate-induced remobilization, and feedback amplification. Empirical observations and scenario-based analyses indicate that climate extremes can trigger order-of-magnitude increases in event-scale PAHs mobilization and intensify cross-media transfer toward the late 21st century, implying that legacy soil reservoirs could become increasingly climate-responsive secondary sources. Accordingly, this review reframes urban PAHs contamination as climate-amplified systemic environmental risks (SERisks), characterized by nonlinear transport behaviors, climate-sensitive feedbacks, and governance challenges across environmental, health, and socio-economic dimensions. Key challenges include: (1) insufficient understanding of PAHs mobility across environmental media; (2) limited insight into climate-amplified feedback mechanisms; and (3) inadequate development of intelligent, adaptive tools for real-time, system-wide risk governance. To translate these insights into practice, we propose a SERisks governance framework that prioritizes real-time, system-wide monitoring, early warning of climate-driven remobilization, and integrated source-to-sink control coupled with AI-assisted, scenario-responsive decision support. This framework bridges pollutant dynamics with climate variability, enabling adaptive SERisks governance in complex urban systems.