The review aims to present the effects of climate change on biodiversity and its remedial measures using Nature based solution (Nbs). At least 40% of the world’s economy, and 80% of the economy of less industrialized nations, is derived directly from biological resources as a function of ecosystem service. Climate change is a key driver for mass extinction, latitudinal and altitudinal shifts of species location, change in species richness and composition, change in phenology, decline in ecosystem services and outbreak of plant and animal disease. The most important notable drivers behind the current loss of biodiversity are habitat modification, overexploitation, climate change, invasive alien species, and chains of extinction. Loss in biodiversity has been attributed primarily to changes in the intensity by which the land and sea are used (34% contribution to losses over the past century) and direct exploitation of species (23%), followed by climate change and pollution (14% each). The impact of climate change is projected to surpass other threats during the twenty-first century both through direct effects and intensifying interactions with other drivers. Under a global warming scenario of 1.5 °C warming, 6% of insects, 8% of plants and 4% of vertebrates are projected to lose over half of their climatically determined geographic range. For global warming of 2 °C, the comparable fractions are 18% of insects, 16% of plants and 8% of vertebrates. Future warming of 3.2 °C above preindustrial levels is projected to lead to loss of more than half of the historical geographic range in 49% of insects, 44% of plants, and 26% of vertebrates. Nature based solutions such as protection of intact ecosystems, managing working lands and restoring native cover are some of the important measures for climate change mitigation and biodiversity protection, although it will be difficult to achieve without the reduction fossil fuel emissions.
NbS Approach: Disaster Risk Reduction
Ecosystem-based disaster risk reduction
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.
Globally, rising seas threaten massive numbers of people and significant infrastructure. Adaptation strategies increasingly incorporate nature-based solutions. New science can illuminate where these solutions are appropriate in urban environments and what benefits they provide to people. Together with stakeholders in San Mateo County, California, USA, we co-developed nature-based solutions to support adaptation planning. We created six guiding principles to shape planning, summarized vulnerability to sea-level rise and opportunities for nature-based solutions, created three adaptation scenarios, and compared multiple benefits provided by each scenario. Adaptation scenarios that included investments in nature-based solutions deliver up to eight times the benefits of a traditionally engineered baseline as well as additional habitat for key species. The magnitude and distribution of benefits varied at subregional scales along the coastline. Our results demonstrate practical tools and engagement approaches to assessing the multiple benefits of nature-based solutions in an urban estuary that can be replicated in other regions.
The major event that hit Europe in summer 2021 reminds society that floods are recurrent and among the costliest and deadliest natural hazards. The long-term flood risk management (FRM) efforts preferring sole technical measures to prevent and mitigate floods have shown to be not sufficiently effective and sensitive to the environment. Nature-Based Solutions (NBS) mark a recent paradigm shift of FRM towards solutions that use nature-derived features, processes and management options to improve water retention and mitigate floods. Yet, the empirical evidence on the effects of NBS across various settings remains fragmented and their implementation faces a series of institutional barriers. In this paper, we adopt a community expert perspective drawing upon LAND4FLOOD Natural flood retention on private land network (https://www.land4flood.eu) in order to identify a set of barriers and their cascading and compound interactions relevant to individual NBS. The experts identified a comprehensive set of 17 barriers affecting the implementation of 12 groups of NBS in both urban and rural settings in five European regional environmental domains (i.e., Boreal, Atlantic, Continental, Alpine-Carpathian, and Mediterranean). Based on the results, we define avenues for further research, connecting hydrology and soil science, on the one hand, and land use planning, social geography and economics, on the other. Our suggestions ultimately call for a transdisciplinary turn in the research of NBS in FRM.
Bangladesh is one of the world’s most vulnerable countries to climate change because of its flat and low-lying topography. The country’s coastal areas are most susceptible to river erosion, flooding, tropical cyclones, salinity intrusion, and tidal surges. Natural and human-induced hazards and disasters have a ripple effect on the ecosystem, resulting in the loss of human lives, property, and the valuable resources needed for human subsistence. The review summarizes the current literature, highlighting the vulnerability index, local-level adaptation strategies, and future research work. The reviewed literature
has reported common hazards like tropical cyclones and tidal waves that can cause tidal floods and riverbank erosion, all of which have a high-to-medium impact on the structure of homes, income, wealth, and employment. Agriculture is the most vulnerable sector in the coastal areas. Aquaculture, shrimp, open-water fish collection, and infrastructure are all vulnerable to disasters in coastal areas. The widely used vulnerability indexes are Livelihood Vulnerability Index (LVI), Coastal Vulnerability Index (CVI) and principal components (PCs) reported in the literature. The local level adaptation strategy is to build the house on high land using bamboo and wood. The pond/gher bound ponds by the net to protect fish from the overflow water, put soil on the gher dike, and sell fish as soon as possible. Diseases of shrimp viruses and white fishes use calcium carbonate, fertilizer, and potash alum as preventative measures. The farmer converted their agricultural land into gher for fish/shrimp cultivation. The community stored/harvested rainwater in a plastic pot or soil pot. The study results will help the government with landscape planning and a disaster-prevention plan at the local level
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).
Flooding is the most frequent and damaging natural hazard globally. While nature-based solutions can reduce flood risk, they are not part of mainstream risk management. We develop a probabilistic risk analysis framework to quantify these benefits that (1) accounts for frequent small events and rarer large events, (2) can be applied to large basins and data-scarce contexts, and (3) quantifies economic benefits and reduction in people affected. Measuring benefits in terms of avoided losses enables the integration of nature-based solutions in standard cost-benefit analysis of protective infrastructure. Results for the Chindwin River basin in Myanmar highlight the potential consequences of deforestation on long-term flood risk. We find that loss reduction is driven by small but frequent storms, suggesting that current practice relying on large storms may underestimate the benefits of nature-based solutions. By providing average annual losses, the framework helps mainstream nature-based solutions in infrastructure planning or insurance practice.
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.
The formulation of management plans as required by EU environmental policies such as the Floods Directive may facilitate the uptake of nature-based solutions (NBS) into practice. Previous research has indicated that the uptake of NBS in water management plans is still low and hindered by various elements of the existing water governance system. However, research so far neglected the role of water managers as “plan-makers” of solution strategies and programs of measures, as well as their beliefs in choosing certain measures in the plan-making process. The aim of this study is to shed more light on the plan-makers’ reasoning for integrating, or not integrating, NBS into specific flood risk management plans (FRMPs). We conducted ten qualitative interviews with plan-makers from Germany and adopted a grounded theory approach to identify their beliefs that underlie the process of formulating FRMPs as well as their perceived role in this process. The analysis reveals a dominance of shared substantive and relational beliefs that are obstructive to a greater uptake of NBS in FRMPs. In particular, identified beliefs about NBS often do not align with their self-perception of their role in being the “plan-makers”. We present a differentiated portrait of water managers as key actors in the decision-making on FRMPs, illustrating that while water managers are belonging to the same distinct professional group with a similar social role in the decision-making process, they do not necessarily share the same preferences.
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.
Coral reefs are effective natural coastal flood barriers that protect adjacent communities. Coral degradation compromises the coastal protection value of reefs while also reducing their other ecosystem services, making them a target for restoration. Here we provide a physics-based evaluation of how coral restoration can reduce coastal flooding for various types of reefs. Wave-driven flooding reduction is greatest for broader, shallower restorations on the upper fore reef and between the middle of the reef flat and the shoreline than for deeper locations on the fore reef or at the reef crest. These results indicate that to increase the coastal hazard risk reduction potential of reef restoration, more physically robust species of coral need to be outplanted to shallower, more energetic locations than more fragile, faster-growing species primarily being grown in coral nurseries. The optimization and quantification of coral reef restoration efforts to reduce coastal flooding may open hazard risk reduction funding for conservation purposes.
Nature-based solutions (NBS) are usually defined as complementary or alternative solutions to “grey infrastructures” (traditionally made with cement) aimed at conserving and regenerating the functionality of natural and semi-natural ecosystems. The research to date shows a considerable potential of NBS to address the current challenges related to climate change and geo-hydrological risks. Despite significant interest in NBS by researchers and practitioners, knowledge concerning their practical implementation, monitoring, and evaluation is still lacking. This is particularly true for large-scale NBS. The present paper discusses how such solutions can be implemented in the context of hydro-meteorological risk reduction in small Mediterranean catchments with a strong tourist vocation. The work presented here is situated within the RECONECT Project (Regenerating ECOsystems with Nature-based solutions for hydro-meteorological risk rEduCTion), which aims to contribute to a European reference framework on NBS by demonstrating, upscaling, and replicating large-scale NBS in rural and natural areas. The Italian case study of RECONECT is the Portofino Natural Regional Park, which represents a unique natural landscape element with high ecologic, social, and economic (touristic) value, which is threatened by a range of geo-hydrological hazards, such as flash floods, hyper-concentrated floods, shallow landslides, rockfalls, and storm surges. This paper also presents details of NBS interventions in two pilot catchments (San Fruttuoso and Paraggi) visited by thousands of tourists throughout the year. It addresses some of the key aspects related to monitoring meteorological and hydrological processes, as well as remote sensing activities (i.e., LiDAR surveys), which are necessary for the identification of critical-instability areas along waterways and the reconstruction of dry stone walls. Lastly, a discussion of relevant mitigation and adaptation strategies that are potentially replicable at national and international levels is also provided.
Low-lying coastal zones are increasingly exposed to flood risks due to global change including sea level rise, increasing storm intensity and growing coastal population densities. Local to regional-scale studies have demonstrated that conservation or restoration of coastal wetland ecosystems, such as salt marshes and mangroves, provides nature-based risk mitigation, as these wetlands have the natural capacity to mitigate the impacts of storm surges and related flood risks. Yet, it is unknown how important this nature-based mitigation of coastal flood risks is on a global scale. Here we present the results of a global-scale GIS model assessing the global distribution of inland surface areas and population numbers exposed to storm surges that would first propagate through tidal wetlands before they reach the inhabited land, and hence that would receive storm surge mitigation by the mangrove forests and salt marshes. Further our model quantifies the distance travelled by a storm surge through the tidal wetlands as a measure of the magnitude of storm surge mitigation. Results show that on a worldwide scale, about 30% of the flood-exposed low-lying coastal plain benefits from nature-based storm surge mitigation by tidal wetlands, with the largest areas located in deltas (e.g. Pearl River, Yangtze, Mekong) and estuaries (e.g. Elbe). Areas protected by large wetlands, where a storm surge would first propagate through >5 km of tidal wetlands before it reaches vulnerable land and people, are located in river deltas such as of the Guayas (Ecuador), Mississippi (USA) and Ganges-Brahmaputra (India and Bangladesh). About 35% of the global flood-exposed coastal population receives nature-based storm surge mitigation. The majority of that population (80%) is located in five countries, i.e. China, Vietnam, the Netherlands, India and Germany. Areas more exposed to extreme storm surges (Eastern America, Caribbean Sea, Eastern Asia) include hotspot areas where storm surges are travelling through wider tidal wetlands generating higher risk mitigation, as for example in the Mississippi delta, Chesapeake bay, Ganges-Brahmaputra delta or Yangtze delta. Our global assessment aims to increase general awareness on the capacity of nature-based coastal flood risk mitigation, and to stimulate further local scale analyses in support of its wider application around the world.
The traditional knowledge of indigenous people is often neglected despite its significance in combating climate change. This study uncovers the potential of traditional ecological knowledge (TEK) from the perspective of indigenous communities in Sarawak, Malaysian Borneo, and explores how TEK helps them to observe and respond to local climate change. Data were collected through interviews and field work observations and analysed using thematic analysis based on the TEK framework. The results indicated that these communities have observed a significant increase in temperature, with uncertain weather and seasons. Consequently, drought and wildfires have had a substantial impact on their livelihoods. However, they have responded to this by managing their customary land and resources to ensure food and resource security, which provides a respectable example of the sustainable management of terrestrial and inland ecosystems. The social networks and institutions of indigenous communities enable collective action which strengthens the reciprocal relationships that they rely on when calamity strikes. Accordingly, the communities maintain their TEK through cultural festivals and oral traditions passed from one generation to another. TEK is a practical tool that helps indigenous communities adapt to climate risks and promotes socio-ecological resilience, which upholds social empowerment and sustainable resource management.
While the benefits humans gain from ecosystem functions and processes are critical in natural resource-dependent societies with persistent poverty, ecosystem services as a pathway out of poverty remain an elusive goal, contingent on the ecosystem and mediated by social processes. Here, we investigate three emerging dimensions of the ecosystem service-poverty relationship: economic contribution of provisioning ecosystem services to the household livelihood mix, social-ecological systems producing different bundles of ecosystem services and material wealth versus reported life satisfaction. We analyse these relationships in Bangladesh, using data from a bespoke 1586-household survey, stratified by seven social-ecological systems in the delta coastal region. We create poverty lines to ensure comparability with traditional poverty measures that overlook environmental factors and subjective measurements of well-being. We find that any contribution of ecosystem service-based income to the livelihood mix decreases the likelihood of the incidence of poverty, and of individuals reporting dissatisfaction. We find no relationship between the incidence of material poverty and the specific social-ecological systems, from agriculture to fishery-dominated systems. However, the probability of the household head being dissatisfied was significantly associated with social-ecological system. Individuals living in areas dominated by export-oriented shrimp aquaculture reported lower levels of life satisfaction as an element of their perceived well-being. These results highlight the need for social policy on poverty that accounts for the diversity of outcomes across social-ecological systems, including subjective as well as material dimensions of well-being. National poverty reduction that degrades ecosystem services can have negative implications for the subjective wellbeing of local populations.
We elevate the undervalued role of wetland protective services for mitigating disastrous consequences of unprecedented weather-related events for human communities. Scientific evidence increasingly reveals that wetlands play critical hydrologic roles in landscapes, helping to mitigate flood, drought, and, in some cases, fire risks. However, wetland protective services have not received sufficient policy action. We propose national wetland commissions, modeled after the concept of lake and river commissions, as one way to strategically link wetland protection to other societal objectives, including human disaster risk planning, infrastructure investments, and climate adaptation strategies. We offer an example applicable to the United States, describing an institutional design for a National Interagency Wetland Commission. We suggest it could be patterned after existing federal commissions statutorily created by Congress with delegated administrative and regulatory authority and designated independent agency status within the executive branch. It is time for bold and innovative policy action to incorporate wetland protective services into societies’ defenses against extreme weather events.
Inclusion of ecosystem-based approaches in the governmental masterplan for tsunami mitigation in Palu, Indonesia may make the city a rare case study for ecological disaster risk reduction in tropical biodiversity hotspots. Such case studies are a key pillar of the United Nations (UN) Sendai Framework to protect coastal societies globally.
The increasing impacts of climate hazards combined with the loss of coastal habitats require urgent solutions to manage risk. Storm losses continue to grow and much of them are uninsured. These losses represent an increasing burden to individuals, businesses, and can jeopardize national development goals. Pre-hazard mitigation is cost effective, but both the public and private sector struggle to finance up-front investments in it. This article explores a resilience solution that combines risk transfer (e.g., insurance) with risk reduction (e.g., hazard mitigation), which have often been treated as two separate mechanisms for disaster risk management. The combined mechanism could help align environmental and risk management goals and create opportunities for public and private investment in nature-based projects. We assessed this resilience insurance with hypothetical cases for coral reef restoration. Under conservative assumptions, 44% of the initial reef restoration costs would be covered just by insurance premium reductions in the first 5 years, with benefits amounting >6 times the total costs over 25 years. We also test the sensitivity to key factors such as project cost, risk reduction potential, insurance structure, economic exposure and discount rates. The resilience insurance mechanism is applicable to many coastlines and can help finance nature-based adaptation.
Oyster reefs have the potential as eco-engineers to improve coastal protection. A field experiment was undertaken to assess the benefit of oyster breakwater reefs to mitigate shoreline erosion in a monsoon-dominated subtropical system. Three breakwater reefs with recruited oysters were deployed on an eroding intertidal mudflat at Kutubdia Island, the southeast Bangladesh coast. Data were collected on wave dissipation by the reef structures, changes in shoreline profile, erosion-accretion patterns, and lateral saltmarsh movement and related growth. This was done over four seasons, including the rainy monsoon period. The observed wave heights in the study area ranged 0.1–0.5 m. The reefs were able to dissipate wave energy and act as breakwaters for tidal water levels between 0.5–1.0 m. Waves were totally blocked by the vertical relief of the reefs at water levels <0.5 m. On the lee side of the reefs, there was accretion of 29 cm clayey sediments with erosion reduction of 54% as compared to control sites. The changes caused by the deployed reefs also facilitated seaward expansion of the salt marsh. This study showed that breakwater oyster reefs can reduce erosion, trap suspended sediment, and support seaward saltmarsh expansion demonstrating the potential as a nature-based solution for protecting the subtropical coastlines.
‘Ocean Cities’ of the Pacific are where urban landscapes and seascapes meet, where built and natural environments interface, and where human behaviour and urban development have profound impacts on both terrestrial and marine ecosystems. Ocean Cities are at the forefront of climate change consequences, urbanisation challenges, and other development pressures. This article discusses the potential for nature-based solutions (NbS), including those focused on ecosystem services, in Pacific Small Island Developing States (SIDS) as a response to climate change, population growth, and urbanisation. Attention is directed to identifying the benefits of NbS and case-studies from Pacific SIDS, and if not available regionally, further afield. The article provides focus on possible barriers to implementation of NbS in a Pacific SIDS context and potential policy responses to these. Conclusions are threefold: (i) addressing interlinked ecological, climate, and human wellbeing issues in an integrated, ocean-focused and climate-responsive manner is vital for sustainable development in island systems; (ii) NbS can provide significant human wellbeing and biodiversity benefits in this context; and (iii) Pacific Ocean Cities, with a significant body of relevant traditional knowledge and emerging NbS experience, can inform global understanding of how to address converging urbanisation and climate change issues in Ocean Cities.
Hydro-meteorological hazards (HMHs) have had a strong impact on human societies and ecosystems. Their impact is projected to be exacerbated by future climate scenarios. HMHs cataloguing is an effective tool to evaluate their associated risks and plan appropriate remediation strategies. However, factors linked to HMHs origin and triggers remain uncertain, which poses a challenge for their cataloguing. Focusing on key HMHs (floods, storm surge, landslides, droughts, and heatwaves), the goal of this review paper is to analyse and present a classification scheme, key features, and elements for designing nature-based solutions (NBS) and mitigating the adverse impacts of HMHs in Europe. For this purpose, we systematically examined the literature on NBS classification and assessed the gaps that hinder the widespread uptake of NBS. Furthermore, we critically evaluated the existing literature to give a better understanding of the HMHs drivers and their interrelationship (causing multi-hazards). Further conceptualisation of classification scheme and categories of NBS shows that relatively few studies have been carried out on utilising the broader concepts of NBS in tackling HMHs and that the classification and effectiveness of each NBS are dependent on the location, architecture, typology, green species, environmental conditions as well as interrelated non-linear systems. NBS are often more cost-effective than hard engineering approaches used within the existing systems, especially when taking into consideration their potential co-benefits. We also evaluated the sources of available data for HMHs and NBS, highlighted gaps in data, and presented strategies to overcome the current shortcomings for the development of the NBS for HMHs. We highlighted specific gaps and barriers that need to be filled since the uptake and upscaling studies of NBS in HMHs reduction is rare. The fundamental concepts and the key technical features of past studies reviewed here could help practitioners to design and implement NBS in a real-world situation.
Climate change will drive significant changes in vegetation cover and also impact efforts to restore ecosystems that have been disturbed by human activities. Bitumen mining in the Alberta oil sands region of western Canada requires reclamation to “equivalent land capability”, implying establishment of vegetation similar to undisturbed boreal ecosystems. However, there is consensus that this region will be exposed to relatively severe climate warming, causing increased occurrence of drought and wildfire, which threaten the persistence of both natural and reclaimed ecosystems. We used a landscape model, LANDIS‐II, to simulate plant responses to climate change and disturbances, forecasting changes to boreal forests within the oil sands region. Under the most severe climate forcing scenarios (Representative Concentration Pathway, RCP, 8.5) the model projected substantial decreases in forest biomass, with the future forest being dominated by drought‐ and fire‐tolerant species characteristic of parkland or prairie ecosystems. In contrast, less extreme climate forcing scenarios (RCPs 2.6 and 4.5) had relatively minor effects on forest composition and biomass with boreal conifers continuing to dominate the landscape. If the climate continues to change along a trajectory similar to those simulated by climate models for the RCP 8.5 forcing scenario, current reclamation goals to re‐establish spruce‐dominated boreal forest will likely be difficult to achieve. Results from scenario modelling studies such as ours, and continued monitoring of change in the boreal forest, will help inform reclamation practices, which could include establishment of species better adapted to warmer and drier conditions.
Global human population growth, limited space for settlements and a booming tourism industry have led to a strong increase of human infrastructure in mountain regions. As this infrastructure is highly exposed to natural hazards, a main role of mountain forests is to regulate the environment and reduce hazard probability. However, canopy disturbances are increasing in many parts of the world, potentially threatening the protection function of forests. Yet, large-scale quantitative evidence on the influence of forest cover and disturbance on natural hazards remains scarce to date. Here we quantified the effects of forest cover and disturbance on the probability and frequency of torrential hazards for 10,885 watersheds in the Eastern Alps. Torrential hazard occurrences were derived from a comprehensive database documenting 3,768 individual debris flow and flood events between 1986 and 2018. Forest disturbances were mapped from Landsat satellite time series analysis. We found evidence that forests reduce the probability of natural hazards, with a 25 percentage point increase in forest cover decreasing the probability of torrential hazards by 8.7 ± 1.2 %. Canopy disturbances generally increased the probability of torrential hazard events, with the regular occurrence of large disturbance events being the most detrimental disturbance regime for natural hazards. Disturbances had a bigger effect on debris flows than on flood events, and press disturbances were more detrimental than pulse disturbances. We here present the first large scale quantification of forest cover and disturbance effects on torrential hazards. Our findings highlight that forests constitute important green infrastructure in mountain landscapes, efficiently reducing the probability of natural hazards, but that increasing forest disturbances can weaken the protective function of forests.
Nature-based solutions (NbS) are highlighted in international agreements such as the Sendai Framework for Disaster Risk Reduction 2015–2030 as promising strategies to reduce disaster risk, adapt to climatic change, and strengthen community resilience. Particular focus is placed on the role of vegetation to prevent or mitigate the impacts of natural hazards and climatic extreme events. Protection forests that aim to minimize the risk of shallow landslides and other slope processes are among the numerous examples of how vegetation can reduce disaster risk and support communities to cope with natural hazards. However, there is no existing systematic review of the protection functions that vegetation offers in different mountain environments and many studies only focus on one specific controlling factor – such as the root systems – without considering NbS as an integrated concept. We performed a detailed investigation into shallow landslides as the most frequent slope processes, and conducted a systematic literature review based on two peer-reviewed bibliographic databases, Scopus and Science Direct, to ascertain the extent to which vegetation is identified as a controlling factor and the targeting of NbS for risk reduction. We assessed more than 13,000 articles published from 2000 to 2018 and conducted an in-depth evaluation of the 275 articles that satisfied the assessment criteria. Our results show that despite the promotion of NbS in internal policies, little research has been published on this topic; however, this has increased over the last decade. We therefore encourage transdisciplinary studies that integrate NbS for shallow landslides reduction.
Mangroves shelter coastlines during hazardous storm events with coastal communities experiencing mangrove deforestation are increasingly vulnerable to economic damages resulting from cyclones. To date, the benefits of mangroves in terms of protecting coastal areas have been estimated only through individual case studies of specific regions or countries. Using spatially referenced data and statistical methods, we track from 2000 to 2012 the impact of cyclones on economic activity in coastal regions inhabited by nearly 2,000 tropical and subtropical communities across 23 major mangrove-holding countries. We use nighttime luminosity to represent temporal trends in coastal economic activity and find that direct cyclone exposure typically results in permanent loss of 5.4–6.7 mo for a community with an average mangrove extent (6.3 m per meter of coastline); whereas, a community with more extensive mangroves (25.6 m per meter of coastline) experiences a loss equivalent to 2.6–5.5 mo. These results suggest that mangrove restoration efforts for protective benefits may be more cost effective, and mangrove deforestation more damaging, than previously thought.