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.
Archives: Publications
Although decades of research suggest that higher species richness improves ecosystem functioning and stability, planted forests are predominantly monocultures. To determine whether diversification of plantations would enhance aboveground carbon storage, we systematically reviewed over 11,360 publications, and acquired data from a global network of tree diversity experiments. We compiled a maximum dataset of 79 monoculture to mixed comparisons from 21 sites with all variables needed for a meta-analysis. We assessed aboveground carbon stocks in mixed-species planted forests vs. (a) the average of monocultures, (b) the best monoculture, and (c) commercial species monocultures, and examined potential mechanisms driving differences in carbon stocks between mixtures and monocultures. On average, we found that aboveground carbon stocks in mixed planted forests were 70% higher than the average monoculture, 77% higher than commercial monocultures, and 25% higher than the best performing monocultures, although the latter was not statistically significant. Overyielding was highest in four-species mixtures (richness range 2–6 species), but otherwise none of the potential mechanisms we examined (nitrogen-fixer present vs. absent; native vs. non-native/mixed origin; tree diversity experiment vs. forestry plantation) consistently explained variation in the diversity effects. Our results, predominantly from young stands, thus suggest that diversification could be a very promising solution for increasing the carbon sequestration of planted forests and represent a call to action for more data to increase confidence in these results and elucidate methods to overcome any operational challenges and costs associated with diversification.
Nature-based solutions (NbS) involve working with nature to address societal challenges in ways that benefit communities and biodiversity locally. However, their role supporting economic recovery from crises, such as those arising from conflicts or pandemics remains underexplored. To address this knowledge gap, we conducted a systematic review of 66 reviews on the economic impact of nature-based interventions. Most demonstrated positive outcomes for income and employment, though those with critical appraisal of underlying studies reported more mixed outcomes. These varied results were influenced by factors such as the balance between short-term and long-term gains, market conditions, regional effects, reliance on subsidies, and discrepancies between expected and actual economic benefits. National-scale economic growth assessments were scarce. Half of the cases featured nature-based food production investments, with much evidence from sub-Saharan Africa, East Asia and the Pacific. The few reviews comparing NbS with alternatives found that NbS delivered equal or better economic outcomes. NbS also provided broader benefits like food and water security, flood protection and community empowerment. We identified key factors influencing the delivery of benefits and trade-offs, finding that NbS must adhere to best practice standards, with community involvement being critical for equitable outcomes. Well-designed NbS can create diverse job opportunities at different skill levels, diversify income, and improve resilience, offering a rapid, flexible response to economic shocks that can be targeted at deprived communities. By integrating traditional, local and scientific knowledge, NbS can enable eco-innovation, and drive the transition to a clean and efficient circular economy, with high economic multipliers spreading benefits throughout economies. The evidence underscores the need to incorporate NbS in investment programs to concurrently address economic, environmental, and societal challenges. However, improved monitoring of economic, social and ecological outcomes and the development of comprehensive accounting systems are needed to better track public and private investments in NbS.
Natural ecosystems store large amounts of carbon globally, as organisms absorb carbon from the atmosphere to build large, long-lasting, or slow-decaying structures such as tree bark or root systems. An ecosystem’s carbon sequestration potential is tightly linked to its biological diversity. Yet when considering future projections, many carbon sequestration models fail to account for the role biodiversity plays in carbon storage. Here, we assess the consequences of plant biodiversity loss for carbon storage under multiple climate and land-use change scenarios. We link a macroecological model projecting changes in vascular plant richness under different scenarios with empirical data on relationships between biodiversity and biomass. We find that biodiversity declines from climate and land use change could lead to a global loss of between 7.44-103.14 PgC (global sustainability scenario) and 10.87-145.95 PgC (fossil-fueled development scenario). This indicates a self-reinforcing feedback loop, where higher levels of climate change lead to greater biodiversity loss, which in turn leads to greater carbon emissions and ultimately more climate change. Conversely, biodiversity conservation and restoration can help achieve climate change mitigation goals.
As conservation initiatives expand in response to biodiversity loss, there remains limited understanding about what forms of governance and roles for different actors produce the best ecological outcomes. Indigenous peoples’ and local communities’ (IPs’ and LCs’) roles extend beyond participation to more equitable governance based on relative control and recognition of their values and institutions, but the relationship with conservation outcomes remains unclear. We review 648 empirical studies to develop a typology of IP and LC roles in governance and, for a subsample of 170, analyze relationships with reported ecological outcomes. The findings reveal that more equitable governance, based on equal partnership or primary control for IPs and LCs, are associated with significantly more positive ecological outcomes. This carries important implications, including for actions toward the Global Biodiversity Framework targets, suggesting a need to elevate the role of IPs and LCs to conservation leaders while respecting their rights and customary institutions.
This independent economic study, commissioned by the RSPB, National Trust and The Wildlife Trusts, is the best evidence yet for how much investment is needed and how it needs to be spent. The analysis shows an annual investment of up to £5.9 billion will be required for at least the next ten years, demonstrating a costed pathway to deliver legally binding nature and climate targets, and ultimately help secure the future of British farming.
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.
Scaling funding to effective nature-based solutions (NbS) for adaptation is key to tackle climate change and support sustainable development. NbS can play a crucial role in adaptation and investments deliver multidimensional benefits for climate mitigation, resilience, people and livelihoods as well as the protection, maintenance, or enhancement of biodiversity. UNEP estimates that approximately $11tn of investment in NbS is required between 2022 to 2050, equating to over $500bn of annual investment by 2030. This means that investment into NbS needs to be quickly and drastically scaled from its current levels of around $200bn per year.
Globalization increasingly allows countries to externalize the environmental costs of land use, including biodiversity loss1. So far, we have a very incomplete understanding of how countries cause biodiversity loss outside their own borders through their demand for agricultural and forestry products grown in other countries2. Here we quantify the global range losses to forest vertebrates from 2001 to 2015 caused by deforestation attributable to 24 developed countries by means of their consumption of products obtained through global supply chains. We show that these driver countries are responsible for much greater cumulative range loss to species outside their own borders than within them. These international impacts were concentrated geographically, allowing us to map global hotspots of outsourced losses of biodiversity. Countries had the greatest external impacts on species occurring in nearby regions. However, in a few cases, developed countries also inflicted disproportionate harm on vertebrates in distant countries.
Pathways to achieving net zero carbon emissions commonly involve deploying reforestation, afforestation, and bioenergy crops across millions of hectares of land. It is often assumed that by helping to mitigate climate change, these strategies indirectly benefit biodiversity. Here, we modeled the climate and habitat requirements of 14,234 vertebrate species and show that the impact of these strategies on species’ habitat area tends not to arise through climate mitigation, but rather through habitat conversion. Across locations, reforestation tends to provide species more habitat through both land-cover change and climate mitigation, whereas habitat loss from afforestation and bioenergy cropping typically outweighs the climate mitigation benefits. This work shows how and where land-based mitigation strategies can be deployed without inadvertently reducing the area of habitat for global biodiversity.
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.
This report analyzed nearly 300 nature-based solutions (NBS) projects across sub-Saharan Africa from 2012 to 2023. It offers a comprehensive overview of NBS in the region: what climate resilience objectives projects are addressing, where projects are occurring and at what scale, how they are funded, and intended co-benefits. It also provides recommendations to scale NBS projects for climate resilience. This report was co-developed by the WRI and the World Bank, with key contributions from the African Development Bank.
Tropical forests play a crucial role in achieving the sustainable development goals by contributing to climate stability, conserving biodiversity and sustaining livelihoods. However, forests are disappearing due to agricultural expansion. In West Africa, cocoa production is a major driver of deforestation. This study examines the design and implementation of forest-focused supply chain policies (FSPs) in cocoa supply chains in Côte d’Ivoire and Ghana, the world’s two leading cocoa producers. FSPs are voluntary policies of companies to combat deforestation, restore forests, and improve farmers’ livelihoods. Drawing on 91 stakeholder interviews, we developed a conceptual framework to examine FSPs’ theory of change, implementation and potential effectiveness and equity. Our findings reveal shortcomings in FSPs’ design and implementation. FSPs are mostly narrowly focused on preventing illegal deforestation and only target farmers in companies’ ‘direct’ supply chains, neglecting important landscape-scale approaches and processes. Companies also fail to include smallholder farmers sufficiently in policy design and implementation. Lastly, FSPs prioritise productivity enhancement but overlook the importance of addressing farmers’ social norms and values. We provide recommendations on how to address the shortcomings to achieve sustainable cocoa production.
International commitments advocate large-scale forest restoration as a nature-based solution to climate change mitigation through carbon (C) sequestration. Mounting evidence suggests that mixed compared to monospecific planted forests may sequester more C, exhibit lower susceptibility to climate extremes and offer a broader range of ecosystem services. However, experimental studies comprehensively examining the control of tree diversity on multiple C stocks and fluxes above- and belowground are lacking. To address this gap, we leverage data from the Sardinilla experiment in Panama, the oldest tropical tree diversity experiment, which features a gradient of one-, two-, three- and five-species mixtures of native tree species. Over 16 years, we measured multiple above- and belowground C stocks and fluxes, ranging from tree aboveground C, over leaf litter C production, to soil organic carbon (SOC). We show that tree diversity significantly increased aboveground C stocks and fluxes, with a 57% higher gain in aboveground tree C in five-species mixtures compared to monocultures (35.7 ± 1.8 vs. 22.8 ± 3.4 Mg C ha−1) 16 years after planting. In contrast, we observed a net reduction in SOC (on average −11.2 ± 1.1 Mg C ha−1 across diversity levels) and no significant difference in SOC3 stocks (the predominantly tree-derived, i.e., C3 plant-derived SOC fraction) between five-species mixtures and monocultures (13.0 ± 0.9 vs. 15.1 ± 1.3 Mg C ha−1). Positive tree diversity effects persisted despite repeated climate extremes and strengthened over time for aboveground tree growth. Structural equation models showed that higher tree growth in mixtures enhanced leaf litter and coarse woody debris C fluxes to the soil, resulting in a tightly linked C cycle aboveground. However, we did not observe significant links between above- and belowground C stocks and fluxes. Our study elucidates the mechanisms through which higher tree diversity bolsters the climate mitigation potential of tropical forest restoration. Restoration schemes should prioritize mixed over monospecific planted forests.
As momentum builds behind hugely ambitious initiatives like the Global Biodiversity Framework (GBF) 30 x 30 target and the European Union’s (EU’s) Biodiversity and Forestry Strategies, there is a danger that hard-won local conservation gains will be dissipated through leakage, the displacement of human activities that harm biodiversity away from the site of an intervention to other places (1). These off-site damages may be less than on-site gains—in which case the action is still beneficial but less so than it superficially seems. However, if activities are displaced to more biodiverse (or less productive) places, leakage impacts may exceed local benefits, so that well-intentioned efforts cause net harm. There is a pressing need for leakage effects like this to be acknowledged and as far as possible avoided or mitigated—through demand reduction, careful selection of conservation or restoration sites, or compensatory increases in production in lower-impact areas.
Many governments and industries are relying on future large-scale, land-based carbon dioxide (CO2) removal (CDR) to avoid making necessary steep greenhouse gas (GHG) emission cuts today. Not only does this risk locking us into a high overshoot above 1.5°C, but it will also increase biodiversity loss, imperiling the Kunming-Montreal Global Biodiversity Framework (KMGBF) goals (4). Such CDR deployments also pose major economic, technological, and social feasibility challenges; threaten food security and human rights; and risk overstepping multiple planetary boundaries, with potentially irreversible consequences. We propose three ways to build on the Intergovernmental Panel on Climate Change (IPCC) analyses of CDR mitigation potential by assessing sustainability risks associated with land-use change and biodiversity loss: estimate the sustainable CDR budget based on socioecological thresholds; identify viable mitigation pathways that do not overstep these thresholds; and reframe governance around allocating limited CDR supply to the most legitimate uses.
This research was conducted over the last year as part of the Hitachi-Imperial Centre for Decarbonisation and Natural Climate Solutions, with the aim of better understanding biodiversity and ecosystem function relationships. While we know that biodiversity often improves ecosystem functioning and so the provision of nature-based solutions, our goal was to synthesise disparate studies to build a complete, quantitative picture of how different kinds of ecosystem functions respond to biodiversity, since the shape of the relationship will be key for designing future interventions.
Animal pollination is important for more than 75% of agricultural crops, including coffee, whose productivity can increase with adequate pollination. Bees, including many solitary species, are diverse pollinators, with around 85% of them considered more effective than honeybees in pollen transfer. We assessed the coffee plantation and its surrounding vegetation for solitary bee nesting throughout the coffee flowering season and measured their impact on coffee productivity.
We installed collection stations with trap nests inside a coffee plantation, on the border and inside the native vegetation in a farm in Diamantina, MG, Brazil. We used 10 weekly monitored replicates at least 1 km apart. We evaluated fruiting by autogamy in relation to natural pollination and used the increase in fruit set from pollinators to calculate the farmer’s monetary gain. We recorded bee visits to the exposed flowers during coffee flowering considering both on the edge and inside the coffee plantation. Ripe fruits were dried, counted and weighed. We discovered 132 solitary bee nests outside the plantation, with 54% containing coffee pollen grains, indicating coffee as an essential resource for bees even outside the crop area. More bee visits occurred at the coffee plantation’s edge, resulting in increased fruit production, denser fruits, and rounder fruits in that area. Bagged flowers produced consistent seeds in all locations. The farmer could earn an extra US$1736.37 per hectare if the entire area received the same level of pollination contribution from bees as observed at the coffee border.
Intensive agriculture with high reliance on pesticides and fertilizers constitutes a major strategy for ‘feeding the world’. However, such conventional intensification is linked to diminishing returns and can result in ‘intensification traps’—production declines triggered by the negative feedback of biodiversity loss at high input levels. Here we developed a novel framework that accounts for biodiversity feedback on crop yields to evaluate the risk and magnitude of intensification traps. Simulations grounded in systematic literature reviews showed that intensification traps emerge in most landscape types, but to a lesser extent in major cereal production systems. Furthermore, small reductions in maximal production (5–10%) could be frequently transmitted into substantial biodiversity gains, resulting in small-loss large-gain trade-offs prevailing across landscape types. However, sensitivity analyses revealed a strong context dependence of trap emergence, inducing substantial uncertainty in the identification of optimal management at the field scale. Hence, we recommend the development of case-specific safety margins for intensification preventing double losses in biodiversity and food security associated with intensification traps.
This small-scale study identifies the best practice current and emerging NBS in Ireland, through literature review and consultation with experts in the field, which have exhibited the potential to mitigate climate change and its impacts or enable adaptation to the impacts of climate change. Some of the case studies identified in this review may not have been implemented as NBS, but they tackle specific climate and societal problems while also providing ecosystem services, as well as benefits to human well-being and biodiversity.
Sustaining yields for smallholder perennial agriculture under a rapidly changing climate regime may require consideration of landscape features and on-farm management decisions in tandem. Optimising landscape and management may not be possible for maximising yields in any one year but maintaining heterogeneous landscapes could be an important climate adaptation strategy. In this study, we observed elevation, forest patch and shade management gradients affecting smallholder coffee (Coffea arabica) yields in a ‘normal’ year versus the 2015/16 El Niño. We generally found a benefit to yields from having leguminous shade trees and low canopy openness, while maintaining diverse shade or varying canopy openness had more complex influences during a climate shock. The two years of observed climate shock were dominated by either drought or high temperatures, with yield responses generally negative. Climate projections for East Africa predict more erratic rainfall and higher temperatures, which will disproportionately impact smallholder farmers.
The voluntary carbon market has come under intense scrutiny over concerns around the environmental and social integrity of the carbon credits being sold. Even certification bodies are seemingly incapable of delivering on their promise to certify “high-integrity” credits. The certification of jurisdictional REDD+ carbon credits by the Architecture for REDD+ Transactions (ART) to the Government of Guyana (GoG) in December 2022 provides an important case study on the challenges facing the high-integrity carbon market.
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.
Nature-based solutions (NBS) can deliver many benefits to human wellbeing, including some crucial to climate adaptation. We quantitatively assess the global potential of NBS strategies of protection, restoration, and agroforestry by modeling global climate change mitigation and local ecosystem services (water availability, sediment retention, runoff, pollination, nitrogen retention, green water storage, and coastal protection). The strategies with the most potential to help people do not necessarily deliver the most climate change mitigation: per area of conservation action, agroforestry provides substantial benefits (>20% increase in at least one local ecosystem service) to three times more people on average than reforestation while providing less than one tenth the carbon sequestration per unit area. Each strategy delivers a different suite of ecosystem service benefits; for instance, avoided forest conversion provides a strong increase in nitrogen retention (100% increase to 72 million people if fully implemented globally) while agroforestry increases pollination services (100% increase to 3.0 billion people if fully implemented globally). One common disservice shared by all the NBS strategies modeled here is that increased woody biomass increases transpiration, reducing annual runoff and in some watersheds negatively impacting local water availability. In addition, the places with the greatest potential for climate change mitigation are not necessarily the ones with the most people. For instance, reforestation in Latin America has the greatest climate change mitigation potential, but the greatest ecosystem service benefits are in Africa. Focusing on nations with high climate mitigation potential as well as high local ecosystem service potential, such as Nigeria in the case of reforestation, India for agroforestry, and the Republic of Congo for avoided forest conversion, can help identify win-win sites for implementation. We find that concentrating implementation of these three conservation strategies in critical places, covering 5.8 million km2, could benefit 2.0 billion people with increased local ecosystem services provision. These critical places cover only 35% of the possible area of implementation but would provide 80% of the benefits that are possible globally for the selected set of ecosystem services under the NBS scenarios examined here. We conclude that targeting these critical places for protection, restoration, and agroforestry interventions will be key to achieving adaptation and human wellbeing goals while also increasing nature-based carbon mitigation.