- Many national governments have incorporated nature-based solutions (NbS) in their plans to reduce net greenhouse gas emissions. However, uncertainties persist regarding both feasibility and consequences of major NbS deployment. Using the United Kingdom as a national-level case study, we examined the potential contribution of three terrestrial NbS: peatland restoration, saltmarsh creation and woodland creation.
- While there is substantial political and societal interest in these three NbS, they also have strong potential for competition with other land uses, which will be a critical barrier to substantial deployment. We conducted a national mapping exercise to assess the potential area available for woodland creation. We then assessed the combined climate change mitigation potential to 2100 for the three NbS options under a range of ambition levels.
- In line with the most ambitious targets examined, 2 Mha of land is potentially available for new woodland. However, climate change mitigation benefits of woodland are strongly dependent on management choices. By 2100, scenarios with a greater proportion of broadleaved woodlands outsequester non-native conifer plantations, which are limited by regular timber harvesting.
- Peatland restoration offers the greatest mitigation per unit area, whilst the contribution from saltmarsh creation is limited by the small areas involved. Overall, the contribution of these NbS to the United Kingdom’s net zero emissions target is relatively modest. Even with the most ambitious targets considered here, by 2100, the total cumulative mitigation from the three NbS is equivalent to only 3 years’ worth of UK emissions at current levels.
- Policy implications. Major deployment of nature-based solutions (NbS) is possible in the United Kingdom but reaching ‘net zero’ primarily requires substantial and sustained reductions in fossil fuel use. However, facilitating these NbS at the national scale could offer many additional benefits for people and biodiversity. This demands that policy-makers commit to a UK-wide strategic approach that prioritises the ‘nature’ aspect of NbS. In the push to reach ‘net zero’, climate change mitigation should not be used to justify land management practices that threaten biodiversity ambitions.
NbS Target: Climate Change Mitigation
Climate change mitigation
Limited time and resources remain to constrain the climate crisis. Natural climate solutions represent promising options to protect, manage and restore natural lands for additional climate mitigation, but they differ in (1) the magnitude and (2) immediacy of mitigation potential, as well as (3) cost-effectiveness and (4) the co-benefits they offer. Counter to an emerging preference for restoration, we use these four criteria to propose a general rule of thumb to protect, manage and then restore lands, but also show how these criteria explain alternative prioritization and portfolio schemes. This hierarchy offers a decision-making framework for public and private sector actors to optimize the effectiveness of natural climate solutions in an environment in which resources are constrained, and time is short.
This book presents new research on innovative financial instruments and approaches available to implement and mainstream nature-based solutions (NBS) at various scales and in different contexts. This book explores various public, private, and blended financing tools available to develop NBS across terrestrial and marine ecosystems, involving multiple stakeholders and in jurisdictions of varying climates and income levels. Furthermore, the book provides case studies of the innovative application of financing to scale up NBS, with best practices identified.
The two most urgent and interlinked environmental challenges humanity faces are climate change and biodiversity loss. We are entering a pivotal decade for both the international biodiversity and climate change agendas with the sharpening of ambitious strategies and targets by the Convention on Biological Diversity and the United Nations Framework Convention on Climate Change. Within their respective Conventions, the biodiversity and climate interlinked challenges have largely been addressed separately. There is evidence that conservation actions that halt, slow or reverse biodiversity loss can simultaneously slow anthropogenic mediated climate change significantly. This review highlights conservation actions which have the largest potential for mitigation of climate change. We note that conservation actions have mainly synergistic benefits and few antagonistic trade-offs with climate change mitigation. Specifically, we identify direct co-benefits in 14 out of the 21 action targets of the draft post-2020 global biodiversity framework of the Convention on Biological Diversity, notwithstanding the many indirect links that can also support both biodiversity conservation and climate change mitigation. These relationships are context and scale-dependent; therefore, we showcase examples of local biodiversity conservation actions that can be incentivized, guided and prioritized by global objectives and targets. The close interlinkages between biodiversity, climate change mitigation, other nature’s contributions to people and good quality of life are seldom as integrated as they should be in management and policy. This review aims to re-emphasize the vital relationships between biodiversity conservation actions and climate change mitigation in a timely manner, in support to major Conferences of Parties that are about to negotiate strategic frameworks and international goals for the decades to come.
Emerging research points to large greenhouse gas mitigation opportunities for activities that are focused on the preservation and maintenance of ecosystems, also known as natural climate solutions (NCS). Despite large quantifications of the potential biophysical and carbon benefits of these activities, these estimates hold large uncertainties and few capture the socio-economic bounds. Furthermore, the uptake of NCS remains slow and information on the enabling factors needed for successful implementation, co-benefits, and trade-offs of these activities remain underrepresented at scale. As such, we present a systematic review that synthesizes and maps the bottom-up evidence on the contextual factors that influence the implementation of NCS in the peer-reviewed literature. Drawing from a large global collection of (primarily case study-based, N = 211) research, this study (1) clarifies the definition of NCS, including in the context of nature-based solutions and other ecosystem-based approaches to addressing climate change; (2) provides an overview of the current state of literature, including research trends, opportunities, gaps, and biases; and (3) critically reflects on factors that may affect implementation in different geographies. We find that the content of the reviewed studies overwhelmingly focuses on tropical regions and activities in forest landscapes. We observe that implementation of NCS rely, not on one factor, but a suite of interlinked enabling factors. Specifically, engagement of indigenous peoples and local communities, performance-based finance, and technical assistance are important drivers of NCS implementation. While the broad categories of factors mentioned in the literature are similar across regions, the combination of factors and how and for whom they are taken up remains heterogeneous globally, and even within countries. Thus our results highlight the need to better understand what trends may be generalizable to inform best practices in policy discussions and where more nuance may be needed for interpreting research findings and applying them outside of their study contexts.
Land-based climate mitigation measures have gained significant attention and importance in public and private sector climate policies. Building on previous studies, we refine and update the mitigation potentials for 20 land-based measures in >200 countries and five regions, comparing “bottom-up” sectoral estimates with integrated assessment models (IAMs). We also assess implementation feasibility at the country level. Cost-effective (available up to $100/tCO2eq) land-based mitigation is 8–13.8 GtCO2eq yr−1 between 2020 and 2050, with the bottom end of this range representing the IAM median and the upper end representing the sectoral estimate. The cost-effective sectoral estimate is about 40% of available technical potential and is in line with achieving a 1.5°C pathway in 2050. Compared to technical potentials, cost-effective estimates represent a more realistic and actionable target for policy. The cost-effective potential is approximately 50% from forests and other ecosystems, 35% from agriculture, and 15% from demand-side measures. The potential varies sixfold across the five regions assessed (0.75–4.8 GtCO2eq yr−1) and the top 15 countries account for about 60% of the global potential. Protection of forests and other ecosystems and demand-side measures present particularly high mitigation efficiency, high provision of co-benefits, and relatively lower costs. The feasibility assessment suggests that governance, economic investment, and socio-cultural conditions influence the likelihood that land-based mitigation potentials are realized. A substantial portion of potential (80%) is in developing countries and LDCs, where feasibility barriers are of greatest concern. Assisting countries to overcome barriers may result in significant quantities of near-term, low-cost mitigation while locally achieving important climate adaptation and development benefits. Opportunities among countries vary widely depending on types of land-based measures available, their potential co-benefits and risks, and their feasibility. Enhanced investments and country-specific plans that accommodate this complexity are urgently needed to realize the large global potential from improved land stewardship.
- There is an increasing recognition that, although the climate change and biodiversity crises are fundamentally connected, they have been primarily addressed independently and a more integrated global approach is essential to tackle these two global challenges.
Nature-based Solutions (NbS) are hailed as a pathway for promoting synergies between the climate change and biodiversity agendas. There are, however, uncertainties and difficulties associated with the implementation of NbS, while the evidence regarding their benefits for biodiversity remains limited. - We identify five key research areas where incomplete or poor information hinders the development of integrated biodiversity and climate solutions. These relate to refining our understanding of how climate change mitigation and adaptation approaches benefit biodiversity conservation; enhancing our ability to track and predict ecosystems on the move and/or facing collapse; improving our capacity to predict the impacts of climate change on the effectiveness of NbS; developing solutions that match the temporal, spatial and functional scale of the challenges; and developing a comprehensive and practical framework for assessing, and mitigating against, the risks posed by the implementation of NbS.
- Policy implications. The Conference of the Parties (COP) for the United Nations Framework Convention on Climate Change (COP26) and the Convention on Biological Diversity (COP15) present a clear policy window for developing coherent policy frameworks that align targets across the nexus of biodiversity and climate change. This window should (a) address the substantial and chronic underfunding of global biodiversity conservation, (b) remove financial incentives that negatively impact biodiversity and/or climate change, (c) develop higher levels of integration between the biodiversity and climate change agendas, (d) agree on a monitoring framework that enables the standardised quantification and comparison of biodiversity gains associated with NbS across ecosystems and over time and (e) rethink environmental legislation to better support biodiversity conservation in times of rapid climatic change.
Alongside the steep reductions needed in fossil fuel emissions, natural climate solutions (NCS) represent readily deployable options that can contribute to Canada’s goals for emission reductions. We estimate the mitigation potential of 24 NCS related to the protection, management, and restoration of natural systems that can also deliver numerous co-benefits, such as enhanced soil productivity, clean air and water, and biodiversity conservation. NCS can provide up to 78.2 (41.0 to 115.1) Tg CO2e/year (95% CI) of mitigation annually in 2030 and 394.4 (173.2 to 612.4) Tg CO2e cumulatively between 2021 and 2030, with 34% available at ≤CAD 50/Mg CO2e. Avoided conversion of grassland, avoided peatland disturbance, cover crops, and improved forest management offer the largest mitigation opportunities. The mitigation identified here represents an important potential contribution to the Paris Agreement, such that NCS combined with existing mitigation plans could help Canada to meet or exceed its climate goals.
Harnessing nature-based climate solutions (NbCS) to help simultaneously achieve climate and conservation goals is an attractive win-win. The contribution of NbCS to climate action relies on both biogeochemical potential and the ability to overcome environmental, economic and governance constraints for implementation. As such, estimates of additional NbCS-related terrestrial biosphere storage potential range from less than 100 GtCO2 to more than 800 GtCO2. In this Review, we assess the negative emissions contributions of NbCS — including reforestation, improved forest management and soil carbon sequestration — alongside their environmental, social and governance constraints. Given near-term implementation challenges and long-term biogeochemical constraints, a reasonable value for the expected impact of NbCS is up to 100–200 GtCO2 in negative emissions for the remainder of the twenty-first century. To sustainably reach this level, focus should be on projects with clear co-benefits, and must not come at the expense of a reduction in emissions from deforestation and forest degradation, rapid decarbonization and innovation from alternative negative emissions technologies.
Key points
There is growing evidence that traditional response to floods and flood-related disaster is no longer achieving desirable results. Nature-Based Solutions (NBS) represent a relatively new response towards disaster risk reduction, water security, and resilience to climate change, which has a potential to be more effective and sustainable than traditional measures. However, in practice, these measures are still being applied at a slow rate while traditional grey infrastructure remains as a preferred choice. This can be attributed to several barriers which range from political and governance to social and technological/technical. More generally, there is a lack of sufficient knowledge base to accelerate their wider acceptance and uptake. The present work provides contribution in this direction and addresses the question of effectiveness of different types of NBS (i.e., small- and large-scale NBS) and their hybrid combinations with grey infrastructure. The work has been applied on the case of Ayutthaya, Thailand. The results suggest that the effectiveness of small-scale NBS is limited to smaller rainfall events whereas the larger (or extreme) events necessitate combinations of different kinds of measures with different scales of implementation (i.e., hybrid measures).
While climate change and biodiversity loss have exposed humanity to major systemic risks, policymakers in more than 40 countries have proposed the transition from a fossil-based to a bio-based economy as a solution to curb the risks. In the boreal region, forests have a prominent role in contributing to bioeconomy development; however, forest-based bioeconomy transition pathways towards sustainability and the required actions have not yet been identified. Participatory backcasting was employed in this study to ‘negotiate’ such pathways among Finnish stakeholders by 2060 in three forest-based value networks: forest biorefineries, fibre-based packaging and wooden multistorey construction. There are many alternative pathways, ranging from incremental to more radical, to a forest-based bioeconomy within a framework of ambitious climate and biodiversity targets. Path dependence can support incremental development on bioeconomy transition pathways, and this should be considered when planning transition towards sustainability. Orchestration of the more radical changes requires actions from legislators, raw material producers, consumers and researchers, because the possibilities for business development vary between different companies and value networks. The envisioned actions between the pathways in and across the networks, such as forest diversification and diverse wood utilisation, can offer co-benefits in climate change mitigation and biodiversity protection.
1. Abandonment of agricultural land is widespread in many parts of the world, leading to shrub and tree encroachment. The increase of flammable plant biomass, that is, fuel load, increases the risk and intensity of wildfires. Fuel reduction by herbivores is a promising management strategy to avoid fuel build-up and mitigate wildfires. However, their effectiveness in mitigating wildfire damage may depend on a range of factors, including herbivore type, population density and feeding patterns.
2. Here, we review the evidence on whether management with herbivores can reduce fuel load and mitigate wildfires, and if so, how to identify suitable management that can achieve fire mitigation objectives while providing other ecosystem services. We systematically reviewed studies that investigated links between herbivores, fire hazard, fire frequency and fire damage.
3. We found that, in general, herbivores reduce fuel load most effectively when they are mixed feeders, when grazing and browsing herbivores are combined and when herbivore food preferences match the local vegetation. In some cases, the combination of herbivory with other management strategies, such as mechanical clearing, is necessary to reduce wildfire damage.
4. Synthesis and Applications. We conclude that herbivores have the capacity to mitigate wildfire damage, and we provide guidance for grazing management for wildfire mitigation strategies. As areas undergoing land abandonment are particularly prone to wildfires, the maintenance or promotion of grazing by domestic or wild herbivores is a promising tool to reduce wildfire risk in a cost-effective way, while also providing other ecosystem services. Relevant land-use policies, including fire suppression policies, agricultural and forest(ry) policies could incentivise the use of herbivores for better wildfire prevention.
Land degradation continues to be an enormous challenge to human societies, reducing food security, emitting greenhouse gases and aerosols, driving the loss of biodiversity, polluting water, and undermining a wide range of ecosystem services beyond food supply and water and climate regulation. Climate change will exacerbate several degradation processes. Investment in diverse restoration efforts, including sustainable agricultural and forest land management, as well as land set aside for conservation wherever possible, will generate co-benefits for climate change mitigation and adaptation and more broadly for human and societal well-being and the economy. This review highlights the magnitude of the degradation problem and some of the key challenges for ecological restoration. There are biophysical as well as societal limits to restoration. Better integrating policies to jointly address poverty, land degradation, and greenhouse gas emissions and removals is fundamental to reducing many existing barriers and contributing to climate-resilient sustainable development.
Given the worldwide plans for extensive tree planting we urgently need to understand how and where implementation will contribute to goals such as those for carbon sequestration. We used a long-term, large-scale native reforestation project in the Scottish Highlands to assess the response of carbon storage and other ecosystem functions to reforestation and grazing exclusion. We measured above-ground carbon, topsoil carbon, topsoil nitrogen, decomposition rates, soil invertebrate feeding activity, tree regeneration, and ground-layer and moss height at 14 sites that are in the early stages of reforestation and fenced to exclude grazing. Reforestation areas were compared to unforested and mature forest areas that are both grazed and ungrazed, using 10 × 10 m plots. Above-ground carbon in the reforestation plots (1.4 kg/m² [95% CI: 0.6, 2.6], average age 20 years since reforestation) was c. 8% of the mature forest plots (17.1 kg/m² [13.1, 21.8]). Topsoil carbon was lower in the reforestation plots (18.78 kg/m² [11.79, 25.78]) than in the unforested (29.82 kg/m² [24.34, 35.29]) or mature forest (31.39 kg/m² [22.91, 39.88]) plots. Responses of other functions to the reforestation and grazing interventions varied. Our results suggest that reforestation may trigger carbon loss from areas with high initial soil carbon even with low disturbance establishment, at least in the short term. Our work emphasises where we lack knowledge: on the potential for long-term re-accumulation of soil carbon under semi-natural native reforestation, soil carbon sequestration in the deeper soil layers and the response of soil carbon to natural regeneration.
As storm-driven coastal flooding increases under climate change, wetlands such as saltmarshes are held as a nature-based solution. Yet evidence supporting wetlands’ storm protection role in estuaries—where both waves and upstream surge drive coastal flooding—remains scarce. Here we address this gap using numerical hydrodynamic models within eight contextually diverse estuaries, simulating storms of varying intensity and coupling flood predictions to damage valuation. Saltmarshes reduced flooding across all studied estuaries and particularly for the largest—100 year—storms, for which they mitigated average flood extents by 35% and damages by 37% ($8.4 M). Across all storm scenarios, wetlands delivered mean annual damage savings of $2.7 M per estuary, exceeding annualised values of better studied wetland services such as carbon storage. Spatial decomposition of processes revealed flood mitigation arose from both localised wave attenuation and estuary-scale surge attenuation, with the latter process dominating: mean flood reductions were 17% in the sheltered top third of estuaries, compared to 8% near wave-exposed estuary mouths. Saltmarshes therefore play a generalised role in mitigating storm flooding and associated costs in estuaries via multi-scale processes. Ecosystem service modelling must integrate processes operating across scales or risk grossly underestimating the value of nature-based solutions to the growing threat of storm-driven coastal flooding.
Negative CO2 emissions are a key mitigation measure in emission scenarios consistent with temperature limits adopted by the Paris Agreement. It is commonly assumed that the climate–carbon cycle response to a negative CO2 emission is equal in magnitude and opposite in sign to the response to an equivalent positive CO2 emission. Here we test the hypothesis that this response is symmetric by forcing an Earth system model with positive and negative CO2 emission pulses of varying magnitude and applied from different climate states. Results indicate that a CO2 emission into the atmosphere is more effective at raising atmospheric CO2 than an equivalent CO2 removal is at lowering it, with the asymmetry increasing with the magnitude of the emission/removal. The findings of this study imply that offsetting positive CO2 emissions with negative emissions of the same magnitude could result in a different climate outcome than avoiding the CO2 emissions.
Minimising the environmental impacts of biofuel production is an urgent global challenge. Over the next decade, increased demand for sugarcane-based ethanol in Brazil could result in over one million hectares of the nation’s native forest and grassland being replaced directly by sugarcane or indirectly by displaced crops and pastureland. Here we integrate future ethanol demand scenarios in Brazil within a spatially-explicit planning framework aimed at minimising impacts of ethanol-driven agricultural expansion on aboveground carbon stocks and 453 species of immediate conservation concern. We show that ethanol-driven agricultural expansion that is blind to carbon and biodiversity values would release 44.9 million tonnes of CO2 equivalent (MtCO2eq), and would impact habitat for at least 273 species. When compared to this conservation-blind scenario, agricultural expansion that avoids carbon and biodiversity values would reduce emissions by 87% (5.8 MtCO2eq) and would avoid impacts on habitat for 113 species. These findings are immediately relevant to policy makers seeking to guide ethanol-driven land-use change away from important environmental areas in Brazil. Our planning methodology can also be extended to other natural areas at risk of bioenergy-driven agricultural expansion.
Amazonia hosts the Earth’s largest tropical forests and has been shown to be an important carbon sink over recent decades. This carbon sink seems to be in decline, however, as a result of factors such as deforestation and climate change. Here we investigate Amazonia’s carbon budget and the main drivers responsible for its change into a carbon source. We performed 590 aircraft vertical profiling measurements of lower-tropospheric concentrations of carbon dioxide and carbon monoxide at four sites in Amazonia from 2010 to 2018. We find that total carbon emissions are greater in eastern Amazonia than in the western part, mostly as a result of spatial differences in carbon-monoxide-derived fire emissions. Southeastern Amazonia, in particular, acts as a net carbon source (total carbon flux minus fire emissions) to the atmosphere. Over the past 40 years, eastern Amazonia has been subjected to more deforestation, warming and moisture stress than the western part, especially during the dry season, with the southeast experiencing the strongest trends. We explore the effect of climate change and deforestation trends on carbon emissions at our study sites, and find that the intensification of the dry season and an increase in deforestation seem to promote ecosystem stress, increase in fire occurrence, and higher carbon emissions in the eastern Amazon. This is in line with recent studies that indicate an increase in tree mortality and a reduction in photosynthesis as a result of climatic changes across Amazonia.
Afforestation plays an important role in soil carbon storage and water balance. However, there is a lack of information on deep soil carbon and water storage. The study investigates the effect of returning farmland to the forest on soil carbon accumulation and soil water consumption in 20-m deep soil profile in the hilly and gully region of the Chinese Loess Plateau. Four sampling sites were selected: Platycladus orientalis (Linn.) Franco forest (PO: oriental arborvitae), Pinus tabulaeformis Carr. Forest (PT: southern Chinese pine), apple orchard (AO) and farmland (FL, as a control). Soil organic carbon (SOC) and soil inorganic carbon (SIC) content were measured in 50-cm sampling intervals of 20-m soil profiles, as well as the associated factors (e.g. soil water content). The mean SOC content of PT was the highest in the 1–5 m layer and that of FL was the lowest (p < 0.05). Compared with FL, the SOC storages of PO, PT and AO increased by 2.20, 6.33 and 0.90 kg m−2 (p > 0.05), respectively, in the whole profile. The SIC content was relatively uniform throughout the profile at all land-use types and SIC storage was 9–10 times higher than SOC storage. The soil water storage of PO, PT and AO was significantly different from that of FL with a decrease of 1169.32, 1161.60 and 1139.63 mm, respectively. After the 36-yrs implementation of the “Grain for Green” Project, SOC in 20 m soil profiles increased as a water depletion cost compared with FL. Further investigation is still needed to understand the deep soil water and carbon interactions regarding ecological restoration sustainability in the Northern Loess Plateau.
Forests play a key role in humanity’s current challenge to mitigate climate change thanks to their capacity to sequester carbon. Preserving and expanding forest cover is considered essential to enhance this carbon sink. However, changing the forest cover can further affect the climate system through biophysical effects. One such effect that is seldom studied is how afforestation can alter the cloud regime, which can potentially have repercussions on the hydrological cycle, the surface radiation budget and on planetary albedo itself. Here we provide a global scale assessment of this effect derived from satellite remote sensing observations. We show that for 67% of sampled areas across the world, afforestation would increase low level cloud cover, which should have a cooling effect on the planet. We further reveal a dependency of this effect on forest type, notably in Europe where needleleaf forests generate more clouds than broadleaf forests.
Global commitments to protected area expansion should prioritize opportunities to protect climate refugia and ecosystems which store high levels of irrecoverable carbon, as key components of an effective response to biodiversity loss and climate change. The United States and Canada are responsible for one-sixth of global greenhouse gas emissions but hold extensive natural ecosystems that store globally significant above- and below-ground carbon. Canada has initiated a process of protected area network expansion in concert with efforts at reconciliation with Indigenous Peoples, and acknowledged nature-based solutions as a key aspect of climate change mitigation. The US, although not a party to global biodiversity conventions, has recently committed to protecting 30% of its extent by 2030 and achieving the UNFCCC Paris Agreement’s mitigation targets. The opportunities afforded by these dual biodiversity conservation and climate commitments require coordinated national and regional policies to ensure that new protected areas maximize biodiversity-focused adaptation and nature-based mitigation opportunities. We address how global commitments can best inform national policy initiatives which build on existing agency mandates for regional planning and species conservation. Previous analyses of global conservation priorities under climate change have been tenuously linked to policy contexts of individual nations and have lacked information on refugia due to limitations of globally available datasets. Comparison and synthesis of predictions from a range of recently developed refugia metrics allow such data to inform planning despite substantial uncertainty arising from contrasting model assumptions and inputs. A case study for endangered species planning for old-forest-associated species in the US Pacific Northwest demonstrates how regional planning can be nested hierarchically within national biodiversity-focused adaptation and nature-based mitigation strategies which integrate refugia, connectivity, and ecosystem carbon metrics to holistically evaluate the role of different land designations and where carbon mitigation and protection of biodiversity’s resilience to climate change can be aligned.
The need to ensure that rising investment in nature-based climate solutions delivers expected outcomes hinges on incorporating current and future climate into design and implementation. Technical guidelines and formal planning processes serve a purpose in ensuring the quality of climate-informed strategies for local projects. The inherent complexity, cost, and time required to use these tools, however, can make them inaccessible or daunting. Taking lessons learned from a decade of funding over 100 adaptation initiatives in conservation—some of which also provide mitigation benefits—we describe a simple rapid assessment framework for use by practitioners and funders. This framework, which we refer to as the 5Ws (what, when, where, why, and who) of climate-informed action, serves as a guide to make projects more robust to future climate.
Carbon sequestration and storage in mangroves, salt marshes and seagrass meadows is an essential coastal ‘blue carbon’ ecosystem service for climate change mitigation. Here we offer a comprehensive, global and spatially explicit economic assessment of carbon sequestration and storage in three coastal ecosystem types at the global and national levels. We propose a new approach based on the country-specific social cost of carbon that allows us to calculate each country’s contribution to, and redistribution of, global blue carbon wealth. Globally, coastal ecosystems contribute a mean ± s.e.m. of US$190.67 ± 30 bn yr−1 to blue carbon wealth. The three countries generating the largest positive net blue wealth contribution for other countries are Australia, Indonesia and Cuba, with Australia alone generating a positive net benefit of US$22.8 ± 3.8 bn yr−1 for the rest of the world through coastal ecosystem carbon sequestration and storage in its territory.
The increased frequency of extreme rain events due to climate change has garnered attention in Japan. In 2018, the country enacted the Act of Climate Change Adaptation to formulate plans at national and local levels. The government has suggested the use of nature-based solutions (NBSs) across the country to address the increased risk of natural disasters. This study employs scenario analysis to examine the effectiveness of NBSs for the mitigation of flood risk and their implications on the provision of ecosystem services (ESs). Shiga prefecture in Japan enacted its own ordinance in 2015. This ordinance considers existing land use and building regulations to mitigate flood risk. The quantitative analysis assumes nine scenarios up to the year 2050, combining the current policy of Shiga and our original assumption of advance policy options to evaluate the future flood risk and ES. The analysis revealed that land use management can partially mitigate the flood risk by banning new residences and relocating residential land from flood-prone areas to safer areas and converting residential land into forest and paddy fields. It also suggests that both flood risk mitigation and provision of ESs can be further improved if local governments introduce a residence growth management strategy.
There has been a recent surge of interest in Nature-based Solutions, a concept encompassing a broad suite of ideas that have arisen from the intersection of ecology, engineering, sociology and economics. Solutions founded in nature are promised to resolve many issues resulting from global change, including reducing flood risk and air pollution, building social cohesion and enhancing resilience. However, what a Nature-based Solution means in practice remains unstructured and vaguely defined. Specifically, what is meant by Nature-based is not well defined and there has been little effort to rigorously understand how a solution is created. In response, we propose an integrated conceptual framework, extending the service-benefit relationship to include solutions, while acknowledging that multiple types of service exist (ecosystem services, technological services and labour). We present a method to measure the degree to which a solution is Nature-based: calculate the relative contribution of ecosystem services, compared with technological services and labour. The method and framework are applied to projects dealing with problems related to water pollution, demonstrating their applicability. The framework can be a useful tool to guide environmental managers in identifying both the scale and context at which, and the problems to which, Nature-based Solutions are applicable.