Good for me and good for you? Exploring green roofs as climate adaptation with multiple social dilemmas

19:00 Tuesday 28 May




Matteo Roggero (Germany) 1

1 - Humboldt-Universität zu Berlin


The present paper addresses social dilemmas linked to climate adaptation measures. It considers adaptation measures that simultaneously serve different beneficiaries, leading to multiple social dilemmas. The relation between them is then expressed as a function of biophysical conditions. By affecting the type of social dilemma at stake, biophysical conditions determine the type of institutional arrangement necessary to address the social dilemma(s) in place.


The theoretical question above is explored empirically with reference to the case of green roofs, an adaptation measure with multiple benefits, multiple beneficiaries, and thus multiple social dilemmas – calling for different policy instruments. Based on data from 15 global cities, all of which are at the forefront in the adoption of green roofs, a crisp-set Qualitative Comparative Analysis links biophysical conditions, approximated through the average size of green roofs at city level, with the type of policies in place.


The analysis shows that cities with, in average, small green roofs rely on regulations and incentives. Cities with, in average, large green roofs focus instead on communication and network-building. The observed differences in policy instruments across cities can be interpreted as a consistent response to different social dilemmas. Specifically, when installations are small, the social dilemma at play is one of private provision of a public good, which works best through a mix of incentives and regulations. In the case of large installations, instead, private gains are large enough to justify the green roofs regardless of the benefits to others, yet collective action problems emerge – problems best dealt with through communication and networking.


However tentative, the results have implications for the specific case of green roofs as well as for the institutional dimension of climate adaptation. Concerning green roofs, future research is encouraged to expand on the characterization of the available installations, moving away from a focus on surface per capita and towards approaches that distinguish different types of potential adopters, as well as the spatial distribution of the installations. More generally, the analysis shows that it’s worthwhile to move beyond the mere acknowledgement that adaptation faces social dilemmas, and move towards a more nuanced understanding of the multiple and different dilemmas at play.