Economic benefits of ecosystem-based disaster risk reduction and ecosystem-based climate change adaptation: a global review

Ecosystems and ecosystem services may contribute to reduction in disaster risk, sustainable development and climate change adaptation. The potential of Nature-based Solutions (NbS) is now recognized by major national policies and international framework agreements. However, to date there is limited scientific evidence about their economic viability and equity impacts. In this study we developed a global database of 406 observations from 87 peer-reviewed studies published between 2000 and 2020, completing economic evaluations of NbS for Ecosystem-based Climate Adaptation (EbA) and Ecosystem-based Disaster Risk Reduction (Eco-DRR). We examine available scientific knowledge on the economic viability and performance of NbS for Eco-DRR and EbA, both in terms of efficiency and equity. More than 40% of the studies analyze the role of coastal ecosystems, coral reefs, wetlands, and mangroves in attenuating disaster risk, with a special focus on floods, storms and erosion. Abundant are also studies examining forest ecosystems (30%), followed by urban (25%) and riparian ecosystems (23%). A smaller number of studies analyzes agro-ecosystems. The number of studies per region suggests that Europe, Asia, and North America are the regions where most Eco-DRR research was undertaken. Based on our results, 71% of studies found that the ecosystems studied were effective NbS in mitigating hazards. 24% of studies found that the ecosystems were occasionally effective in mitigating hazards. None of the studies found NbS ineffective in mitigating hazards. The ecosystems most frequently effective in mitigating hazards included mangroves (80%), forests (77%), and coastal ecosystems (73%). A subset of studies compared the efficacy and cost-effectiveness of NbS and engineering-based solutions in mitigating certain hazards (39%). Among these studies, 65% found that NbS are always more effective in attenuating hazards compared to engineering-based solutions, and 26% found that NbS are partially more effective. No study found that NbS are less effective than engineering-based solutions.