From Exposure to Resilience: Community-Based Multi-Risk Mapping and Nature-Based Solutions in Brazil’s Urban Peripheries

Climate change exacerbates exposure to extreme weather, magnifies intersecting vulnerabilities, and multiplies the risks faced by urban populations worldwide. Nowhere is this more pressing than in informal settlements, where cascading and compound risks threaten the lives of over one billion people globally (UN-Habitat, 2025). In these contexts, climate hazards—floods, landslides, heatwaves—interact with precarious housing, infrastructural deficits, and socio-economic marginalization, producing unlivable conditions. Addressing these challenges requires integrated strategies that move beyond technocratic assessments of hazard exposure and toward participatory, systemic approaches that combine community knowledge, risk governance, and adaptive design.This talk presents the Planos Comunitários de Redução de Riscos e Adaptação Climática (PCRAs, Community Plans for Disaster Risk Reduction and Climate Adaptation), a pioneering initiative of Brazil’s Secretaria Nacional de Periferias (National Secretariat for Urban Peripheries) within the Brazilian Ministry of Cities. Currently being piloted in twelve urban peripheries across the country, the PCRA seeks to generate place-based and community-driven strategies for disaster risk reduction and climate adaptation. Our contribution focuses on the plan developed in Jardim Colombo, São Paulo, where local residents, civil society organizations, and public authorities co-produce knowledge and solutions, and on a pilot in a neighboring community, Jardim São Remo, in collaboration with scholars and students from the University of São Paulo.Methodologically, we employ a systemic risk matrix that hierarchizes hazards and vulnerabilities, guiding decision-making and the co-selection of NBS interventions. This framework integrates scientific risk assessments with community-based knowledge, generating actionable maps and strategies that serve as both technical planning instruments and mechanisms for community empowerment. By foregrounding systemic risk and NBS in the context of informal settlements, the PCRAs also contribute to national and global debates on equitable adaptation pathways.The work systematised data on seven previously identified risk categories: ground subsidence and mass movements associated with inadequate wastewater disposal and mud intrusion; unhealthy urban configurations marked by poor ventilation and air circulation, favouring humidity retention and respiratory health risks; severe accessibility constraints due to narrow alleys and stairways lacking adequate infrastructure; inadequate sanitation and drainage systems compromising environmental quality and public health; vulnerability to surface runoff, flash flooding, and inundation during intense rainfall events; improper solid waste disposal, contributing to soil, water, and air contamination, drainage obstruction, flood risk, and slope instability; and exposure to extreme heat, adversely affecting health and well-being. In response to this multi-risk context, Nature-based Solutions (NbS) are being proposed as a key strategy for climate risk mitigation in informal settlements, simultaneously addressing the technical challenges identified through the prior risk matrix mapping and the needs and priorities articulated by the local community through participatory workshops.In a context where climate denialism and exclusionary governance have hindered progress, the current Brazilian turn toward participatory policymaking provides an important institutional opening. The PCRAs demonstrates how collaborations between state institutions and peripheral communities can generate innovative and scalable responses to climate risks. More broadly, it contributes to international debates on systemic, community-driven risk governance, underscoring the importance of inclusive adaptation strategies for enhancing the resilience of urban peripheries.