On the cost effectiveness of nature based solutions for reducing disaster risk

Ecosystems and ecosystem services are key to helping achieve reductions in disaster risk, sustainable development, and climate change adaptation (Doswald et al., 2014; Cohen-Shacham et al., 2016; Brink et al., 2016; Chausson et al., 2020; Debele et al., 2023), and this is now recognized by major international agreements (e.g., Sendai Framework for Disaster Risk Reduction (SFDRR) 2015–2030 (United Nations Office for Disaster Risk Reduction, 2015), Sharm el-Sheikh Implementation Plan (UNFCCC-COP27, 2022), Convention on Biological Diversity, 2022 (UNEP, 2022a)). There is growing evidence of benefits of both urban and non-urban of ecosystem-based interventions, also referred to as Nature-based Solutions (NbS) (Sudmeier-Rieux et al., 2021; Pereira et al., 2023). However, there is limited scientific knowledge about the cost-effectiveness and equity outcomes of NbS. This study addresses this knowledge gap by developing a global database of peer-reviewed studies, published between 2000 and 2021, performing an economic evaluation of NbS. We focus on two types of NbS: ecosystem-based approaches to disaster risk reduction (Eco-DRR) and ecosystem-based climate change adaptation (EbA).

The Fifth Session of the United Nations Environment Assembly (UNEA-5) (UNEP, 2022b) resolution formally adopted the definition of NbS as “actions to protect, conserve, restore, sustainably use and manage natural or modified terrestrial, freshwater, coastal and marine ecosystems, which address social, economic and environmental challenges effectively and adaptively, while simultaneously providing human well-being, ecosystem services and resilience and biodiversity benefits”. UNEA-5’s overall theme is “Strengthening Actions for Nature to Achieve the Sustainable Development Goals”. It puts nature at the heart of the global post-pandemic economic recovery and calls on member states to support the implementation of NbS “in partnership with local communities, women and youth as well as with indigenous peoples” (UNEP, 2022c).

The Sharm el-Sheikh Implementation Plan resulting from the 2022 United Nations Climate Change Conference (UNFCCC-COP27, 2022:2) refers to NbS for the first time in the history of climate negotiations and “underlines the urgent need to address, in a comprehensive and synergistic manner, the interlinked global crises of climate change and biodiversity loss in the broader context of achieving the Sustainable Development Goals”.

Numerous global, national, and local organizations and governments are now investing in Eco-DRR and EbA approaches as part of COVID-19 green economic recovery strategies (European Commission, 2020a; IUCN, 2021; Treasury Board of Canada Secretariat, 2021). The EU’s 2030 biodiversity strategy (European Environment Agency, 2021), a key pillar of the 1-trillion-euro European Green Deal, includes a nature restoration plan that can boost the uptake of Nature-based Solutions. During the UNFCCC-COP27 the US Biden-Harris Administration released a Nature-Based Solutions Roadmap, outlining recommendations for scaling up NbS to address climate change, nature loss, and inequality in the United States of America (White House Council on Environmental Quality et al., 2022).

Gathering scientific evidence on the economics and financial aspects of NbS is key. According to the European Commission, more than 200 M euros have been invested in NbS research and demonstration projects between 2016 and 2020, and more than 200 M euros for research on NbS are expected to be available through the European Green Deal and Horizon Europe going forward (European Commission, 2020a). Despite these efforts, to date few peer-reviewed studies summarize the state of scientific knowledge on NbS economic benefits and their distributional outcomes across social groups to support pluralistic decision-making on NbS. More attention is needed to fill these research gaps and develop inclusive NbS performance standards.

This study builds on a recent global assessment (Sudmeier-Rieux et al., 2021) that performed the first systematic review of 529 Eco-DRR peer-reviewed studies across all disciplines, cataloging the extent of confidence in ecosystems in reducing disaster risk. Our analysis goes further by examining the economics of NbS implementation in terms of financing, cost-effectiveness, co-benefits generated, and possible social justice implications across a multi-dimensional spectrum of socio-economic groups. The potential of NbS to be truly pluralistic and transform society is mediated by both tangible and intangible dimensions of power, including participatory research that supports pluralistic knowledge creation (Lehmann et al., 2018; Woroniecki et al., 2020). Besides studying the economic effectiveness of NbS, in our review we examine whether the articles analyzed the nexus between the NbS implemented and income inequalities; gender; race and ethnicity; indigenous groups and local communities; and their contribution to the Sustainable Development Goals.

We generated a global database of 402 observations, from 87 English-language peer-reviewed articles published between 2000 and 2021, which performed economic evaluations of Eco-DRR and EbA interventions. NbS analyzed in this study cover a spectrum of ecosystems, encompassing natural, managed, and newly created ecosystems, as well as ecosystems at different levels on the restoration continuum (Gann et al., 2019). Our findings illustrate multiple factors including the geographic locations of the NbS analyzed, the source of financing, and the economic methodologies employed to assess cost-effectiveness and distributional effects.

source :

https://www.sciencedirect.com/science/article/abs/pii/S0048969724046722?via%3Dihub