Urban green infrastructure can help cities adapt to climate change. Spatial planning can play an important role in utilizing green infrastructure for adaptation. Yet climate change risks represent a different sort of challenge for planning institutions. This paper aims to address two issues arising from this challenge. First, it defines the concept of green infrastructure within the context of climate adaptation. Second, it identifies and puts into perspective institutional barriers to adopting green infrastructure for climate adaptation, including path dependence. We begin by arguing that there is growing confusion among planners and policy makers about what constitutes green infrastructure. Definitional ambiguity may contribute to inaction on climate change adaptation, because it muddies existing programs and initiatives that are to do with green-space more broadly, which in turn feeds path dependency. We then report empirical findings about how planners perceive the institutional challenge arising from climate change and the adoption of green infrastructure as an adaptive response. The paper concludes that spatial planners generally recognize multiple rationales associated with green infrastructure. However they are not particularly keen on institutional innovation and there is a tendency for path dependence. We propose a conceptual model that explicitly recognizes such institutional factors. This paper contributes to the literature by showing that agency and institutional dimensions are a limiting factor in advancing the concept of green infrastructure within the context of climate change adaptation

Urban parks and gardens may be failing to meet the diverse “nature needs” of a growing global urban population. Informal urban greenspace (IGS) such as vacant lots, street or railway verges and riverbanks may provide space for unstructured recreation and nature contact. Yet we know little about residents' relationship with IGS outside of Europe and North America, what factors influence IGS use and evaluation, or what role geographic and cultural context play. Our paper combines qualitative and quantitative methods to examine how residents in Brisbane, Australia (n = 123) and Sapporo, Japan (n = 163) perceive, evaluate and use IGS. Using statistical methods (e.g. correlation analysis) we analyzed what factors influence how respondents interact with IGS, including the amount of formal greenspace within 500m of survey locations using a GIS buffer analysis. Results were tested for differences and similarities between the cities. We found that respondents knew of IGS in their neighborhood (>80%), appreciated and used it (>30%), but more respondents in Brisbane used and appreciated IGS. The influence of demographic factors and local formal greenspace area was limited, but respondents' attitude towards urban nature was correlated with IGS evaluation. Littering was perceived as IGS' most common problem (90% of respondents), but was reported by <20% of IGS users. Geographic (e.g., IGS type prevalence) and cultural (e.g., human-nature relationship) contexts represented potential influence factors. We argue that the liminal nature of IGS (e.g., liability) management poses a challenge traditional greenspace planning. To address this problem, further research should explore participatory management approaches