Governing Urban Heat Adaptation and Green Inequality: Toward a Thermal Justice Architecture — A Scoping Review

Unequal access to urban green spaces (UGS) and disproportionate exposure to urban heat islands (UHI) intensify socio-spatial vulnerability and are closely linked to environmental injustice. Yet evidence remains fragmented on how governance arrangements are associated with equity-oriented urban greening, urban forestry, and vegetation-based heat adaptation. This scoping review analyzes 52 peer-reviewed empirical studies published between 2015 and September 2025, following updated scoping review guidance and PRISMA-ScR reporting standards. The review examines how governance scales, institutional instruments, and justice dimensions were related in studies of UGS distribution, urban greening and urban forestry planning and management, and UHI mitigation. The findings indicate that equity-sensitive adaptation was associated less with greening expansion alone than with the alignment of formal mandates, programmatic allocation, vulnerability metrics, maintenance and monitoring routines, and participatory feedback. Greening or cooling gains were often described alongside uneven benefit distribution, exclusionary trade-offs, or green gentrification, particularly when siting rules remained generic or instruments operated in fragmented ways. Participation was described as improving procedural legitimacy and vulnerability recognition, but it rarely changed redistribution when disconnected from budgeting, siting, implementation authority, or long-term management. Stronger alignment was more often described where vulnerability metrics were used to guide allocation, instruments were connected across scales, and urban greening was coordinated with housing, mobility, land-use, and public-health systems. Conversely, weakened translation was described in configurations involving generic siting rules, fragmented instruments, limited implementation capacity, and participation without decision authority. Building on these patterns, the review advances Thermal Justice Architecture as a provisional construct for synthesizing recurring frictions, boundary conditions, and knowledge gaps in equitable vegetation-based thermal adaptation.