POSITIONING NATURE-BASED SOLUTIONS AND GREY INFRASTRUCTURE IN URBAN CLIMATE ADAPTATION: ADOPTION PATTERNS ACROSS 833 CITIES

Abstract

Amid rapid urbanization and climate change, local governments face the challenge of how to position conventional grey infrastructure, nature-based solutions (NbS), and hybrid strategies within urban climate adaptation. In this context, this study aims to examine, through a descriptive-exploratory approach, the patterns of NbS adoption relative to grey infrastructure across 833 cities reporting to the CDP-ICLEI Track 2025 cycle. The research examines cities' adaptation actions, governance indicators, hazard profiles, and funding sources drawn from the publicly available CDP-ICLEI Track dataset, using frequency analysis and correspondence analysis. The Python programming language was used for analysis and reporting. The findings show that 59.4% of cities reported at least one NbS action; however, in most cities NbS complements grey infrastructure rather than substituting it. Adaptation strategy differs systematically by hazard type, with NbS prominent for ecological hazards and grey infrastructure dominant for hydrological ones. While cities adopting NbS display higher institutional capacity across all governance indicators examined, both strategies depend predominantly on local government resources. NbS projects appear comparatively more open to diversified funding sources. The findings indicate that NbS should be regarded not as a universal alternative but as part of an integrated adaptation approach positioned according to hazard profile.