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Nature-based solutions (NbS) are designed as a win-win strategy to address societal challenges while providing biodiversity, social, and economic benefits. However, uncertainties and gaps persist, particularly regarding the criteria that define a NbS measure and the specific requirements for a solution to be fully recognized as such, which limit the full potential of these strategies in practice. Another persistent issue is the lack of data on strategy responses across different implementation scales (local, city, regional) and climatic zones (temperate, arid, tropical). This article provides an overview of the potential of NbS to promote climate adaptation in cities. Our meta-analysis, which compiled 7163 records from 89 articles worldwide, indicates that integrating NbS strategies with traditional approaches (gray infrastructure and sustainable technologies) is the most effective response to concurrently address multiple climate-related hazards. Flooding had the highest impact at 35.7 %, followed by increased runoff at 30.5 %. Peak flow and water pollution both had an impact of 10.3 %, while temperature increase accounted for 5.7 %, and decreases in thermal comfort made up 5.0 %. We concluded that all evaluated strategies reduced the impact of climate-related hazards, but this reduction was twice as large when incorporating NbS (18.6 % vs 8.1 %). We also demonstrate that this effect is observed under projected climate scenarios, reinforcing the role of NbS in making cities more resilient and sustainable.
RESUMO
BACKGROUND: Freshwaters are the most threatened ecosystems on earth. Although recent assessments provide data on global priority regions for freshwater conservation, local scale priorities remain unknown. Refining the scale of global biodiversity assessments (both at terrestrial and freshwater realms) and translating these into conservation priorities on the ground remains a major challenge to biodiversity science, and depends directly on species occurrence data of high taxonomic and geographic resolution. Brazil harbors the richest freshwater ichthyofauna in the world, but knowledge on endemic areas and conservation in Brazilian rivers is still scarce. METHODOLOGY/PRINCIPAL FINDINGS: Using data on environmental threats and revised species distribution data we detect and delineate 540 small watershed areas harboring 819 restricted-range fishes in Brazil. Many of these areas are already highly threatened, as 159 (29%) watersheds have lost more than 70% of their original vegetation cover, and only 141 (26%) show significant overlap with formally protected areas or indigenous lands. We detected 220 (40%) critical watersheds overlapping hydroelectric dams or showing both poor formal protection and widespread habitat loss; these sites harbor 344 endemic fish species that may face extinction if no conservation action is in place in the near future. CONCLUSIONS/SIGNIFICANCE: We provide the first analysis of site-scale conservation priorities in the richest freshwater ecosystems of the globe. Our results corroborate the hypothesis that freshwater biodiversity has been neglected in former conservation assessments. The study provides a simple and straightforward method for detecting freshwater priority areas based on endemism and threat, and represents a starting point for integrating freshwater and terrestrial conservation in representative and biogeographically consistent site-scale conservation strategies, that may be scaled-up following naturally linked drainage systems. Proper management (e. g. forestry code enforcement, landscape planning) and conservation (e. g. formal protection) of the 540 watersheds detected herein will be decisive in avoiding species extinction in the richest aquatic ecosystems on the planet.