Evidence on the effectiveness of climate change adaptation interventions in low- and middle-income countries has been rapidly growing in recent years, particularly in the agricultural and coastal sectors. Here we address the question of whether results are consistent across intervention types, and risk reduction versus development-related outcomes using a systematic review of 363 empirical observations published in the scientific literature. Generally, we found more evidence of risk reduction outcomes in the coastal sector than in the agricultural sector, and more evidence of development-related outcomes in the agricultural sector. Further, results indicate that nature-based solutions have the strongest positive effects for both the coastal and agricultural sectors. Social/behavioural interventions in the coastal sector show negative effects on development-related outcomes that will need to be further tested. Taken together, our results highlight the opportunity for development and climate adaptation practitioners to promote adaptation interventions with co-benefits beyond risk reduction, particularly in the case of nature-based solutions.
NbS Target: Disaster Risk Reduction
Disaster risk reduction
The potential of ecosystem-based interventions, also known as Nature-based Solutions (NbS), for Disaster Risk Reduction (DRR) and Climate Change Adaptation (CCA) is now recognized by major national policies and international framework agreements. However, there is limited scientific evidence about their economic viability and equity impacts. We examined English-language peer-reviewed studies, published between 2000 and 2021, which undertook economic evaluations of NbS for DRR and CCA. Based on our results, 71 % of studies indicated that NbS have consistently proven to be a cost-effective approach to mitigating hazards and 24 % of studies found NbS cost-effective under certain conditions. The ecosystem-based interventions most frequently found effective in mitigating hazards are associated with mangroves (80 %), forests (77 %), and coastal ecosystems (73 %). Studies comparing the cost-effectiveness of NbS and engineering-based solutions for mitigating certain hazards showed that NbS are no less effective than engineering-based solutions. 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. Our findings illustrate a range of factors, including the geographic locations of the NbS analyzed, their contribution to the restoration and increase of biodiversity, their property rights structure, their source of financing, and the economic methodologies employed to assess cost-effectiveness and distributional effects. The geographic location of the NbS observations included in this analysis was examined considering global projected temperature and precipitation changes.
Integration of Nature-based solution (NBS) as adaptation in planning and policy remains a challenge due to lack of adequate information on economic feasibility. This is mainly due to non-availability of economic evaluation framework for informed decision. Present study tries to address this by examining the status of evaluation frameworks through a systematic review of peer-reviewed articles published between 2015 and 2023. Based on the synthesis of the evidence a five-step framework, exclusively for economic evaluation of NBS as urban adaptation has been developed. Using this a novel, holistic, just, equitable and inclusive cyclical decision tool has been proposed. The review confirmed the lack of economic assessment and a holistic evaluation framework. The evaluation framework has been backed by operational guidance by providing comprehensive recommendations on the methodologies, tools and techniques and indicators and metrics that can be used for execution of each step. The proposed cyclical decision tool facilitates equity and justice by having provisions for ensuring equal participation of each stakeholder in decision making. It specifically ensures incorporation of plurality of knowledge and in particular value of the ecosystem services (ESs) from NBS. The tool has applicability across the urban spatial scale in cities of developed and developing economies.
The Cerrado is the second largest biome in Latin America and the most biodiverse savanna in the world. Yet it has lost half its native vegetation to agriculture – and conversion is accelerating. Urgent action is needed to balance production with protection, in a way that delivers gains for climate, nature and people.
Social contracts are evolving relationships between the government and the public; they describe the rights and responsibilities of each party in catastrophic hydroclimatic events. As the climate crisis unfolds disaster losses continue to increase and the need for new infrastructure is becoming more apparent. Research suggests that incorporating Nature-based Solutions (NbS) into infrastructure adaptations may reduce exposure and loss and improve social well-being. While researchers and policy makers push for NbS, it is unclear whether they adequately recognize contemporary social contracts and whether these contracts are shifting sufficiently to accept the differences. We operationalize social contracts and test a conceptual approach through analysis of tweets before, during and after Hurricane Ida. Our results indicate a social contract of inequalities manifested through experience, perceptions and expectations of citizens. There is a great deal of uncertainty and feelings of insecurity about the public’s perception of government response and resource provisions. Although our results indicated a gap in public perception of NbS, uncertainty about the effectiveness of conventional infrastructure was expressed. Public expectations include an evolving social contract that addresses the challenges related to inequalities while also adapting to climate change. We discuss how this twitter data can be used to understand the role of social contracts in responding to disaster risk and infrastructure adaptation and how inadequacies in current protection measures can inform potential use of NbS.
The creation of wetlands along river channels, or inter-levee floodplain wetlands (ILWs), increases the cross-sectional area of rivers for flood control and is an effective nature-based solution (NbS) that is expected to achieve both flood control and biodiversity conservation in floodplains in riverine areas in Japan. To clarify the differences in habitat functions between ILWs and rice paddy fields, we surveyed the species assemblage and habitat usage of aquatic animal assemblages in ILWs and nearby rice paddies in the Nobi Plain of central Japan. Rana japonica bred in the ILWs, and taxon numbers of Odonata larvae and aquatic Hemiptera were greater in ILWs than in rice paddies. Fish taxa were also more abundant in the ILWs. ILWs were characterized mainly by taxa with a preference for permanent water bodies in their life history, whereas Dryophytes japonicus, Pelophylax porosus brevipodus, and Fejervarya kawamurai inhabited and bred mainly in the rice paddies, and the number of taxa of aquatic Coleoptera was also higher. The assemblages in the rice paddies were characterized by pioneer taxa with a preference for temporary waters as their primary breeding sites. Our results show that the creation of ILWs for flood control and the maintenance of rice paddies could help to conserve the original floodplain biodiversity through the complementarity of these different wetland types.
Coastal flood risk poses a serious, existential threat to shoreline populations around the world both now and in the future. Unsurprisingly, global decision makers are considering their options – one of these being Nature-based Solutions – for effective disaster risk reduction which specifically targets coastal flooding. While strides have been made in the field of Nature-based Solutions for coastal flooding, much of this attention has been directed towards the urban setting, with a wealth of scholastic documentation to support this notion. The sizeable rural populations scattered throughout the world’s small coastal communities, meanwhile, have been largely neglected in academic literature. Without this information, it is impossible to properly capture the full potential of Nature-based Solutions in (global) flood risk modelling endeavours or understand their role in the future of equitable disaster risk reduction. In light of this gap, we have reviewed the limited amount of existing literature from around the world involving the implementation and effectiveness of Nature-based Solutions in small coastal communities. We analysed 28 peer-reviewed studies to gather common themes and insights about the barriers and opportunities unique to these rural shorelines. Takeaways we have identified include a near consistent scarcity of resources (e.g., technical, financial, institutional) to implement disaster risk reduction measures; an abundance of space and opportune land use regimes which make Nature-based Solutions a highly plausible option; amplified nature contributions to people leading to larger benefits reaped from investments into Nature-based Solutions; and the presence of local knowledge regarding societal norms, climate patterns, and ecosystem capabilities. We argue that these four common themes point to the fact that more attention must be given to coastal flooding-focused Nature-based Solutions in the rural setting. As such, we present this collation as a starting point for future projects of similar setting and scope. We also recommend improving benefit-cost analysis methods as well as including local knowledge and other perspectives in future global assessments of coastal flood risk.
Effective disaster risk reduction measures are vital to coastal communities around the world. While nature-based solutions provide coastal communities with a promising alternative to traditional engineering-based solutions; these solutions are often overlooked by communities when planning and implementing disaster risk reduction measures. This study builds upon the literature that demonstrates the effectiveness of coral reef conservation to mitigate coastal flood risk. Our approach utilizes freely available tools and data to quantify the economic value of coral reef conservation for the Hawaiian Islands. We explore a scenario that depicts coastal flooding if the upper 1 m of the coral reef were to be lost. The study analyzes the Average Annual Loss (AAL) and losses avoided based on a series of 4 coastal flood scenario return periods with and without coral reefs. This case study finds that the preservation of the upper 1 m of coral reefs for the main islands of Hawaiʻi provides the state with $629 million in annual losses avoided to buildings. A hot spot analysis of the losses avoided identifies areas where conservation efforts could be prioritized. Our findings provide additional support to the use of nature-based solutions as an effective disaster risk reduction measure, and provides communities and stakeholders with a methodology that can be implemented using readily available data and tools.
The use of nature-based solutions (NbS) to address the risks posed by hydro-meteorological hazards have not yet become part of the mainstream policy response, and one of the main reasons cited for this, is the lack of evidence that they can effectively reduce disaster risk. This paper addresses this issue, by providing model-based evidence from five European case studies which demonstrate the effectiveness of five different NbS in reducing the magnitude of the hazard and thus risk, in present-day and possible future climates. In OAL-Austria, the hazard is a deep-seated landslide, and the NbS analysed is afforestation. Modelling results show that in today’s climate and a landcover scenario of mature forest, a reduction in landslide velocity of 27.6 % could be achieved. In OAL-Germany, the hazard is river flooding and the NbS analysed is managed grazing with removal of woody vegetation. Modelling results show that the NbS could potentially reduce maximum flood water depth in the near-future (2031–2060) and far-future (2070–2099), by 0.036 m and 0.155 m, respectively. In OAL-Greece, the hazard is river flooding, and the NbS is upscaled natural storage reservoirs. Modelling results show that in a possible future climate the upscaled NbS show most potential in reducing the total flooded area by up to 1.26 km2. In OAL-Ireland, the hazard is surface and river flooding, and the NbS is green roofs. Results from a modelled upscaling analysis under two different climate scenarios show that both maximum flood water depth, and total flooded area were able to be reduced. In OAL-UK, the hazard is shallow landslides, and the NbS is high-density planting of two different tree species. Modelling results under two different climate scenarios show that both tree species were able to improve slope stability, and that this increased over time as the NbS matured. The significance of these results is discussed within the context of the performance of the NbS over time, to different magnitude events, impact with stakeholders in engendering wider support for the adoption of the NbS in the OALs, and the uncertainty in the modelling analyses.
Tropical America is a biogeographically megadiverse region, hosting 4 of the 36 global biodiversity hotspots: Tropical Andes, Tumbes-Choco Magdalena, Mesoamerica and the Caribbean islands ; 6 of its 17 countries are considered megadiverse. Such megadiversity is a result of a complex geography which also contributes to the region’s exposure to extreme events and high vulnerability to climate change. In these settings, natural capital1 could be the engine for innovative development and, if better understood, used to increase resilience and adaptation to global environmental change, including potential changes in the magnitude and frequency of extreme events
Nature-based solutions (NbS) have received increased interest as cost-effective contributors to addressing societal challenges, with ecosystem-based disaster risk reduction (Eco-DRR) being the specific approach for reducing disaster risk under the NbS umbrella. Ecosystem services (ES) provided by Eco-DRR measures are known to contribute to reducing all three components of disaster risk. Yet, Eco-DRR evaluation falls short of recognising this, and this hampers its strategic placement and effective use. This paper addresses the challenge of evaluating the impact of Eco-DRR measures on reducing hazard, exposure and vulnerability. The methodological approach for Eco-DRR evaluation is developed for agroforestry as an example of ecosystem-based measure for flood risk reduction. The literature review on ES provided by cropland versus agroforestry provided the basis to elaborate on how the quantitative evaluation of such a measure for flood risk reduction could be realised in a next step. An additional literature review served to create a look-up table on the effects of agroforestry on hydrological processes in comparison to cropland. This can serve as input for re-running the hydrological model and comparing the hazard before and after the agroforestry implementation. The paper also captures the effects of agroforestry implementation on social and ecological vulnerability through changes in ES provision. Changes in ES provision resulting from the implementation of an agroforestry measure on cropland were related to social and ecological vulnerability using a deductive approach. The concept for comprehensive evaluation developed in this paper provides the groundwork for evaluating the risk reduction potential of Eco-DRR with reference to a tailored risk assessment.
Nature-based solutions (NbS) have received increased interest as cost-effective contributors to addressing societal challenges, with ecosystem-based disaster risk reduction (Eco-DRR) being the specific approach for reducing disaster risk under the NbS umbrella. Ecosystem services (ES) provided by Eco-DRR measures are known to contribute to reducing all three components of disaster risk. Yet, Eco-DRR evaluation falls short of recognising this, and this hampers its strategic placement and effective use. This paper addresses the challenge of evaluating the impact of Eco-DRR measures on reducing hazard, exposure and vulnerability. The methodological approach for Eco-DRR evaluation is developed for agroforestry as an example of ecosystem-based measure for flood risk reduction. The literature review on ES provided by cropland versus agroforestry provided the basis to elaborate on how the quantitative evaluation of such a measure for flood risk reduction could be realised in a next step. An additional literature review served to create a look-up table on the effects of agroforestry on hydrological processes in comparison to cropland. This can serve as input for re-running the hydrological model and comparing the hazard before and after the agroforestry implementation. The paper also captures the effects of agroforestry implementation on social and ecological vulnerability through changes in ES provision. Changes in ES provision resulting from the implementation of an agroforestry measure on cropland were related to social and ecological vulnerability using a deductive approach. The concept for comprehensive evaluation developed in this paper provides the groundwork for evaluating the risk reduction potential of Eco-DRR with reference to a tailored risk assessment.
Emergent complex climate risks challenge conventional approaches for climate adaptation (CCA) and disaster risk reduction (DRR). This situation demands new ways of addressing climate risks with integrated solutions. Nature-based Solutions (NbS) are promising CCA and DRR given their cost-effectiveness, multifunctionality and low-regret condition in addressing a wide range of risks exacerbated by climate change. However, little attention has been paid to exploring methodological approaches for combining NbS to reduce climate risks. Still, selecting the appropriate and effective combination of NbS is a challenging task. This research applies a geospatial multi-criteria approach for developing intervention packages of NbS for CCA and DRR and applies this innovative methodology to a case study area in the Puna region in Peru. The study started with an in-depth literature analysis coupled with a participatory process with local experts to identify and select locally valid NbS for CCA and DRR. Building upon that, the overall multi-criteria approach was developed, which consists of a matrix-based procedure to evaluate the applicability of relevant measures and their feasibility of being combined in intervention packages. Then, the multi-criteria analysis was integrated into a Geographic Information System using a spatial analysis model to map suitable intervention areas. Next to the methodological innovation, the multi-criteria approach was applied to a case study area to generate a place-based intervention package for addressing the risk of reduced water provision considering climate change conditions, with its respective potential intervention sites differentiated by the appropriate measures. This methodological approach is a novel and pragmatic support tool that helps practitioners design more robust and effective interventions for building resilience to climate change. Furthermore, this methodological approach involves shifting the perspective from activities focused on “one-size-fits-all-solution” to “multi-solution” strategic interventions that address climate risks more comprehensively, recognizing the dynamics and complexities of the social-ecological systems. The authors encourage researchers and practitioners to transfer the methodological approach to other contexts and, with that, accelerate the efficient and targeted implementation of NbS for building resilience to climate change.
Disaster risk reduction (DRR) is one of the most important societal challenges addressed under the umbrella term nature-based solutions (NbS). One NbS approach that specifically addresses risk reduction is ecosystem-based disaster risk reduction (Eco-DRR). However, there are other approaches, such as integrated fire management or protective forests, which directly aim at reducing the risk of specific natural hazards. Other approaches, such as ecosystem-based adaptation (EbA), do not have DRR as a primary goal, but contribute to it in the form of synergies and co-benefits. Based on a comprehensive literature search of the Scopus database covering all articles published in English during the period 2000–2021, we analyze existing NbS approaches and those which address DRR. In a further step, we select all original research articles (n = 114) that refer to NbS for DRR projects or interventions conducted in a specific geographic area and analyze them in terms of (1) approach applied; (2) natural hazards mitigated; (3) ecosystem services for DRR provided; (4) geographic and biophysical site conditions, and (5) measures and techniques used. The analysis forms the basis for developing a typology of NbS for DRR, which we present for discussion. This typology helps scientists, policymakers, planners, and other stakeholders to gain a systematic overview of the NbS for DRR approaches currently addressed in the literature and to advance systematization of these approaches.
This study performs an economic efficiency and equity analysis of four recent Ecosystem-based Disaster Risk Reduction (Eco-DRR) interventions in Haiti, India, Indonesia, and Uganda. Our analysis aims at contributing to the development of methodological best practices for assessing both the economic-effectiveness and the distributional impacts of nature-based solutions, with a particular focus on marginalized or underserved communities. Nature-based solutions (NbS) are emerging as possible strategies to mitigate disaster risk while providing additional benefits to biodiversity and sustainable economic growth. However, there is limited scientific evidence about the cost-effectiveness and equity outcomes of NbS. For each ecosystem-based intervention examined we performed an economic efficiency assessment through a quantitative cost-benefit analysis (CBA). Our estimates show that at the 5th year since the project implementation, the interventions in Haiti and India generated positive net benefits, assuming hazard-related yearly losses in properties and GDP per capita in the project areas as low as 0.5 %. We observe the same outcomes in Indonesia and Uganda at the 10th year since the project implementation, assuming yearly losses equivalent to 1 % or higher and adopting a 3 % discount rate. When we include additional benefits from carbon capture and sequestration and pollution reduction the CBA net benefits estimates are positive at the 10th year mark for every discount rate adopted. Extensive qualitative interviews of local stakeholders corroborate the CBA results and provide insights on the numerous additional benefits experienced, which in the future could be measured and monetized if monitored over time. A qualitative analysis of the distributional effects of the interventions was performed to complement the economic efficiency assessment. This equity analysis indicates an enhancement in inclusivity, economic equality, participation, and capacity building among local stakeholders. In particular, the Eco-DRR interventions implemented resulted in significant education, health, safety and economic improvements for women, children, and economically vulnerable members of the local communities.
In natural grasslands under extensive grazing, volcanic events pose risks to livestock health and production. Volcanic tephra tends to persist and remain remobilized for years in arid and semi-arid environments, which can be problematic. Healthy wet meadow-wetlands developed in the bottom valleys of Northern Patagonia, Argentina, offer a natural solution for mitigating volcanic tephra impacts. By combining existing geographic information (North Patagonia wetland distribution map and tephra fallout deposit map), the extent of wet meadows affected by the 2011 Puyehue-Cordón Caulle Volcanic Complex (PCCVC) volcano was calculated. The regional amount of available forage in the aftermath of the eruption was estimated through field assessments of aerial net primary production (ANPP); this was conducted during the first peak of plant growth after the PCCVC volcanic event in 5 m x 5 m paired plots, both with and without manually removed tephra a month after the event. To compare the tephra effect on vegetation type throughout time, normalized vegetation index (NDVI) was used to monitor plant activity two years before, the following year, and five years after the PCCVC event in wet meadows and surrounding steppes. In addition, the regional amount of tephra removed from the environment and stabilized in the soil was assessed using prior research findings of ash immobilization and stabilization within meadow soil profiles five years after the PCCVC event. Around 106,000 ha (52%) of North Patagonian meadows were identified to be exposed to volcanic hazard. The plant growing season following the eruption generated, on average, 3929±2146 kg DM ha−1, indicating an active functional wet meadow recovery despite a 25-20% reduction in ANPP due to the tephra effect. NDVI data supported these findings, with the historical maximum level (0.46±0.02) being restored the year following the event, while surrounding steppes recovered at least three years after. Healthy wet meadows mitigated the adverse effects of around 2279 tons of regional tephra, while simultaneously providing nearly half a billion tons of fodder production the year following the eruption- a critical period of cattle food scarcity. These findings highlight the reduction of negative impacts following recurrent volcanic eruptions and underscore the positive effects of conserving, restoring, and sustainably managing wetlands as a Nature-Based Solution for Disaster Risk Reduction.
Nearly two decades ago, the Indian Ocean tsunami created a devastating human tragedy, leaving many questions in its wake as to the role that mangroves may have played in saving lives and livelihoods. Over the following decade, these questions led to the creation of a new field of study: the role of ecosystems in disaster risk reduction, or Eco-DRR. After 2020, Eco-DRR became quasi-synonymous with ‘Nature-based Solutions for disaster risk reduction’, with a few notable differences. What changed as a result of the Indian Ocean tsunami was an increased awareness that ecosystems could – and should – be part of discourse and portfolios of investments in disaster risk reduction (DRR). Over the next two decades, this awareness grew in three phases: 1) 2005–2014: the ‘convincing stage’; 2) 2015–2020: the ‘mainstreaming stage’ 3) 2020: ‘the blue-printing stage’. This collection of articles highlights research on the evidence of the effectiveness of ecosystem approaches for DRR, while addressing the above question: “how to implement”?
The islands of the Caribbean are particularly susceptible to the effects of climate change due to their low-lying coastal areas and location within the Atlantic basin’s hurricane belt. The UK Overseas Territory of Anguilla is one such island. The predicted increase in the severity of hurricanes and sea-level rise is highly likely to increase the flood risk of already vulnerable island communities. In this study, flood risk and erosion models are used to prioritise opportunity areas for nature-based restoration and to identify those that would have the greatest impact on coastal and in-land flood risk reduction. Two study sites in Anguilla were selected to highlight this ecologically-based modelling approach; Cove Bay and Pond, a degraded sand dune system and brackish pond, and the East End Pond, an Important Bird and Biodiversity Area that floods following heavy rainfall events. At the coastal site, the restoration of mangroves, sand dunes and coral reefs have the potential to provide flood risk reduction up to 500 m inland and protect homes, infrastructure and tourism developments. For the in-land East End Pond, areas of high erosion risk were predominately identified as bare or disturbed land within 1 km of the pond’s basin. Restoration of these areas was identified as having the greatest impact on reducing flood risk. The identification of optimal areas for habitat restoration and modelling the positive impact that habitat restoration can have in reducing flood risk are important tools that can be used to inform the implementation of nature-based solutions and also to advocate and justify such management activities to policy makers and landowners.
The risks from climate change are ever-growing, especially in more vulnerable and exposed regions such as coastlines. The rise in sea level and increase in the frequency and intensity of climate-induced coastal hazards are threatening the increasing coastal populations. Brazil, with its 8,500 km of coast, is one of the countries most at risk from coastal flooding and erosion. Nature-based solutions have been suggested as climate adaptation strategies with the greatest potential to counteract coastal hazards stemming from sea-level rise and safeguard coastal cities. However, there is still a knowledge gap in the scientific literature on the effectiveness of nature-based solutions, especially at large spatial scales in Central and South America. Here, we assessed the risks from climate-induced hazards of coastal erosion and flooding related to sea-level rise on the Brazilian coast, and the effectiveness of nature-based solutions as climate adaptation strategies. We reveal that nature-based shoreline protection can reduce by 2.5 times the risks to the Brazilian coastline. The loss of existing natural habitats would substantially increase the area and population at risk from these climate-induced hazards. Worrisomely, legal mechanisms to protect these natural habitats are few and being weakened. Only 10% of the coastal natural habitats are within protected areas, and these alone do not ensure coastal protection, as our results indicate that the loss of unprotected natural habitats has about the same risk as the total absence of natural habitats. Our results warn of the severe consequences of the continued loss of natural habitats along the coast. Thus, actions towards the maintenance and protection of coastal habitats are paramount for climate adaptation and to ensure the well-being and livelihoods of coastal populations. Brazil has a central role in demonstrating the benefits of strategies based on nature-based solutions for shoreline protection, favoring their implementation worldwide. We provide both the natural habitat maps and the maps with model results with spatial and numerical information so readers can explore the relations between the natural habitats and coastal risk indexes at a sub-national level and foster their use by local stakeholders.
Humanity is facing major social and ecological impacts from climate change and biodiversity loss. These two crises are intertwined, with common causes and effects on one another. Pörtner et al. review the results of a joint meeting of members of the International Panels on Climate Change and Biodiversity and Ecosystem Services. They discuss the connections between biodiversity loss and climate change and propose potential solutions for addressing them as interconnected problems. Drastic reductions in greenhouse gas emissions, protection of multiuse landscapes and seascapes, and policies for providing equitable access to natural resources can help to ensure future ecological function and human well-being. —BEL
Humankind faces a Triple Challenge: averting dangerous climate change, reversing biodiversity loss, and supporting the wellbeing of a growing population. Action to address each of these issues is inherently dependent on action to address the others. Local, national, and international policy goals on climate change, biological diversity, and human wellbeing have been set. Current implementation measures are insufficient to meet these goals, but the Triple Challenge can still be met if governments, corporations, and other stakeholders take a holistic perspective on management of land and waters. To inform this effort, we identify a set of priority policy responses drawn from recent international assessments that, whilst not being the only potential solutions, can form the core of such a holistic approach. We do this through an iterative process using three methodological approaches: (i) structured literature review; (ii) deliberative expert analysis; and (iii) wider consultation, before synthesizing into this paper. Context-appropriate implementation of responses will be needed to capitalize on potential policy synergies and to ensure that unavoidable trade-offs between management of land and waters for climate mitigation, biodiversity restoration, and human wellbeing outcomes are made explicit. We also set out four approaches to managing trade-offs that can promote fair and just transitions: (1) social and economic policy pivoting towards ‘inclusive wealth’; (2) more integrated policymaking across the three areas; (3) ‘Triple Challenge dialogues’ among state and non-state actors; and (4) a new research portfolio to underpin (1), (2), and (3).
While the amount of research on NBS is growing rapidly, there is a lack of evidence on community experiences of NBS design and implementation, particularly from low-income and informal settlements of African cities. This article adds new empirical evidence in this space through grounded analysis of NBS “niche” projects co-developed by intermediary organizations and communities in five sites across three settlements in Nairobi and Dar es Salaam. Findings are organized around four established NBS knowledge gaps: (1) NBS-society relations; (2) Design; (3) Implementation; (4) Effectiveness. We find that across the five studied sites, residents’ perceptions and valuation of urban nature has changed through processes of co-design and co-implementation, enabling community ownership of projects, and hence playing a crucial role in NBS effectiveness over time. The integration of gray components into green infrastructure to create hybrid systems has proven necessary to meet physical constraints and communities’ urgent needs such as flood mitigation. However, maintenance responsibilities and cost burdens are persisting issues that highlight the complex reality of NBS development in informal settlements. The cases highlight key considerations for actors involved in NBS development to support the replication, scaling up and institutionalization of NBS. These include the need to: (i) develop forms of engagement that align with co-production values; (ii) capture communities’ own valuation of and motivations with NBS development for integration into design; (iii) elaborate technical guidance for hybrid green-gray infrastructure systems that can be constructed with communities; and (iv) help define and establish structures for maintenance responsibilities (especially governmental vs. civil society) that will enhance the environmental stewardship of public spaces.
Justice and fairness have become key considerations in sustainability pathways and nature-based solutions (NBS), following activists and critical scholars who have long argued that the urban environment is an inherently political space that requires an analysis of benefits and burdens associated with its existence, use, and access. However, what justice means and how it is expressed, recognized, or achieved is often implicit in the literature on NBS, even though underlying notions of justice shape the analysis done and actions proposed. This paper starts from the premise that justice knows many different interpretations, therefore warranting scholars and practitioners working on NBS to carefully consider the differences and frictions between competing meanings of justice. Drawing from the history of social and environmental justice theory, we give an account of some key justice dilemmas and discuss their tenets as it relates to the end, means, and participants in the making of justice. From this, we draw out questions and commitments academics and practitioners in the NBS space should grapple with more explicitly. We argue that the emergent tension between pragmatic policy approaches and critical theoretical engagement is hindering a version of NBS that goes beyond a reflection of the justice implications of NBS to ensuring that NBS contributes to the furthering of justice. We advocate for the inclusion of critical social sciences and humanities perspectives and approaches beyond tokenism to instead encourage ontological, epistemological, and political reflection of the work academics and practitioners do in the NBS space.
Sustaining the organisms, ecosystems and processes that underpin human wellbeing is necessary to achieve sustainable development. Here we define critical natural assets as the natural and semi-natural ecosystems that provide 90% of the total current magnitude of 14 types of nature’s contributions to people (NCP), and we map the global locations of these critical natural assets at 2 km resolution. Critical natural assets for maintaining local-scale NCP (12 of the 14 NCP) account for 30% of total global land area and 24% of national territorial waters, while 44% of land area is required to also maintain two global-scale NCP (carbon storage and moisture recycling). These areas overlap substantially with cultural diversity (areas containing 96% of global languages) and biodiversity (covering area requirements for 73% of birds and 66% of mammals). At least 87% of the world’s population live in the areas benefitting from critical natural assets for local-scale NCP, while only 16% live on the lands containing these assets. Many of the NCP mapped here are left out of international agreements focused on conserving species or mitigating climate change, yet this analysis shows that explicitly prioritizing critical natural assets and the NCP they provide could simultaneously advance development, climate and conservation goals.
Cities increasingly have to find innovative ways to address challenges arising from climate change and urbanization. Nature-based solutions (NBS) have been gaining attention as multifunctional solutions that may help cities to address these challenges. However, the adoption and implementation of these solutions have been limited due to various barriers. This study aims to identify a taxonomy of dominant barriers to the uptake and implementation of NBS and their relationships. Fifteen barriers are identified from the literature and expert interviews and then ranked through a questionnaire. Interpretive Structural Modeling (ISM) serves to identify the mutual interdependencies among these barriers, which results in a structural model of six levels. Subsequently, Cross-impact matrix multiplication applied to classification (MICMAC analysis) is used to classify the barriers into four categories. The results suggest that political, institutional and knowledge-related barriers are the most dominant barriers to NBS. Cities that intend to apply NBS can draw on these findings, especially by more effectively prioritizing and managing their actions.