The climatic dependencies of urban ecosystem services from green roofs: Threshold effects and non-linearity

- We present a method to value benefits obtained from extensive green roofs.
- The discontinuity of the benefits affects long term profitability of green roofs.
- The benefits are nonlinear with respect to the share of green roofs coverage.

This paper proposes a methodology for quantifying benefits and costs of extensive green roofs as an urban strategy for adaptation to climate change. It seeks to highlight the consequences of threshold effects in the delivery of the benefits and non-linearity with respect to green roof coverage. The analysis focuses on energy savings for cooling, carbon footprint reduction, avoided water treatment and reduction of heat-stress related mortality. Applying the methodology to the case study of the city of Madrid (Spain) reveals that for climate scenarios where observed temperatures are closer to thresholds, misspecification of the services is more likely to bias the decision of using green roofs as an urban strategy to mitigate the effects of climate change.