Informal settlements as a systemic risk frontier: reframing urban climate adaptation for inclusive and just resilient futures

Informal settlements are home to more than one billion people worldwide. In these settlements, climate hazards interact with insecure housing, limited services, and weak institutional support, creating risks that can extend beyond settlement boundaries and affect wider urban systems. Although informal settlements are widely recognized as vulnerable, they remain insufficiently integrated into climate policy and urban planning. We use ‘inevitability’ to describe the condition in which adverse climate outcomes are treated as unavoidable, normalized, and repeatedly reproduced through policy neglect, institutional inertia, and unequal exposure to risk. This opinion paper synthesizes research and policy debates from Asia, Africa, and Latin America to examine why these conditions persist and how they can be changed. We conceptualize informal settlements as systemic risk frontiers because disruptions within them can spread through interconnected urban systems, affecting mobility, livelihoods, public health, and service delivery. We also identify ‘pivot states’ as governance-contingent moments in which alternative intervention pathways can be negotiated across actors and scales, such that risk trajectories are either reinforced or redirected. The paper shows how fragmented planning and the exclusion of informal settlements from adaptation processes fail to leverage these pivot states, allowing systemic risk to accumulate, persist, and intensify. It argues that integrating informal settlements into urban climate governance can help break cycles of inevitability, support earlier intervention, reduce vulnerability lock-ins, and create pathways towards deliberate transformation.