International, Multi-disciplinary Team of Researchers Provide an Examination of Evidence for Ecosystem-Based Disaster Risk Reduction

AMHERST, Mass. – Decision-makers around the world are increasingly interested in using ecosystem solutions such as mangroves, coral reefs, sand dunes and forests on steep slopes to help buffer the impacts from hazard events and protect populations. But what evidence exists to show the efficacy of nature-based solutions over man-made protective measures to reduce the impacts of the increasing numbers of hazard events humanity faces?

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An international, multi-disciplinary team of 28 researchers has now examined nearly 20 years’ worth of peer-reviewed studies on the impacts of ecosystem-based disaster risk reduction (DRR) efforts to, for the first time, summarize the state of knowledge of ecosystem services and functions for DRR. The team, including Marta Vicarelli, assistant professor of economics and public policy at the University of Massachusetts Amherst, spent six years reviewing 529 English-language articles to catalog the extent of knowledge on, and confidence in, ecosystems in reducing disaster risk.

As reported in an article published by the journal Nature Sustainability, they found that ecosystems particularly play a role in reducing the disaster risk for forests and the management of wildfires, the mitigation of flooding in urban areas through the implementation of green design and the use of vegetation on steep slopes to cost-effectively reduce mountain hazards, such as mudslides and avalanches. They also found that the role of ecosystems in managing storm water, where potential monetary losses are high, is also considerably notable.

Their review of existing research reveals that persistent droughts, land degradation and desertification are often slow-onset processes in drylands that, over time, may well lead to disaster. Importantly, they found ample evidence of how ecosystem-based approaches in areas susceptible to drought can reduce the impacts of climate change.

The articles in the review were organized into 15 thematic categories and were analyzed by teams of topic specialists, with Vicarelli leading the team analyzing the economics literature. Vicarelli says that the economics papers demonstrated with high level of confidence that ecosystem services and/or functions are cost-effective as well as cost-efficient, particularly with regards to flood mitigation, vegetation cover for slope stabilization and avalanche mitigation.

“The 2004 Indian Ocean tsunami drew the world’s attention to the role of ecosystems in disaster risk reduction,” write the researchers, who represent institutions including the United Nations Environment Programme and universities and organizations in Germany, Switzerland, Singapore, Scotland, the Netherlands, Fiji, Italy, Colombia, India and Sri Lanka. “Coastal ecosystems, in particular mangrove forests, were perceived to have protected some coastal communities from the impacts of the tsunami, even though the scientific evidence for this was, and still is, debated. This and other devastating events triggered an increase in the number of scientific studies examining the role of ecosystem-based approaches to disaster risk reduction.”

The researchers explain that disaster risk is usually expressed as the interaction between three factors: hazard, exposure and vulnerability. Eco-DRR is “the sustainable management, conservation and restoration of ecosystems to reduce disaster risk, with the aim to achieve sustainable and resilient development.” But while an increasing number of policies, laws and agreements at national and international levels are now explicitly addressing ecosystems in their DRR efforts, they report that there is still a paucity of knowledge on this topic. Addressing this gap in scientific evidence will be necessary to support policymakers in considering Eco-DRR measures.

“More attention should be given to evidence-based studies of Eco-DRR, particularly in rapidly growing urban coastal areas and drylands in Asia, Africa, Oceania, Central and South America and the Caribbean,” they write. “These are megadiverse regions, where large populations depend on natural resources for protection and livelihoods.”

“Green infrastructure approaches can be employed as sustainable alternatives to, or to complement, grey engineering protective measures, or the so-called hybrid approaches to DRR,” they conclude, noting that governments have signed international framework agreements and have, in many cases, formulated national policy commitments recommending ecosystem-based measures for DRR. “There is, therefore, great potential globally, most notably in the Global South, for more evidence-based research to be conducted in this nascent field. To help achieve this, there is a need to strengthen research infrastructure and funding attention, particularly in areas where disaster impacts are most prevalent.”

The researchers say that it is especially important to expand research on the socio-economic benefits associated with Eco-DRR and on the possible implications in terms of socio-economic equity, and to address this knowledge gap Vicarelli is currently leading a team on a new research project. They believe that the results of this additional research – expected in the fall of 2021 – will be of great policy importance, as Eco-DRR strategies and other nature-based approaches are being included in COVID-19 sustainable socio-economic recovery plans in the U.S. and abroad.

The complete current report, “Scientific evidence for ecosystem-based disaster risk reduction,” is available online from Nature Sustainability.