By Joséphine Anselin
Abstract
Coastal areas around the UK are increasingly threatened by climate change induced hazards such as flooding and erosion. As our planet continues to warm, the frequency and intensity of these adverse events is expected to rise. Hence, there is a heightened requirement for coastal management strategies aimed at increasing the capability of UK coasts to adapt to these hazards, thereby enhancing resilience to climate change. Nature-based solutions (NbS), such as salt marshes, sand dunes, sea grass and oyster reefs, offer inherently adaptable, cost-effective and environmentally beneficial alternatives to traditional fixed engineered coastal defences. However, location-specific challenges such as funding constraints and social acceptance barriers can hinder their implementation. This article focuses on England’s coastal management strategy. It provides an overview of relevant NbS, including their strengths and weaknesses, and it highlights opportunities and challenges associated with integrating NbS into flooding and erosion risk mitigation plans. Suggestions to address these challenges include re-evaluation of funding frameworks to account for core aspects of NbS, fostering of collaborative partnerships across sectors, and early involvement of local communities in the decision-making process.
Science ⇒ Policy
This article highlights the need for policies that encourage the implementation of nature-based solutions (NbS) to enhance resilience to coastal flooding and erosion in the face of climate change. It highlights collaboration between policy makers, coastal management practitioners, academic experts, and local communities as a key requirement for successful deployment of NbS. Concerns about coastal defence capabilities are also raised to help understand the challenges associated with scaling up NbS. Whilst the geographical focus of the article is England, the insights have broader applicability wherever NbS are considered to prepare for and adapt to uncertain future climate conditions.
Keywords
Cambridge Journal of Science & Policy, Coastal Resilience, Nature, Nature-based solutions (NbS), Climate change
Background
Climate change increases the frequency and intensity of coastal storms [1]. Intensified river discharge and accelerating sea level rise, for examples, enhance the risk of coastal flooding and erosion [2,3]. These coastal hazards can have serious negative consequences including loss of residential property, infrastructure damage, economic disruption, natural habitat degradation, and loss of cultural heritage sites [4].
Under the Climate Change Act 2008, the UK has a legal obligation to develop adaptation plans to address climate change induced risks. Coastal adaptation policy approaches vary between England, Wales, Scotland and Northern Ireland due to coastal management being devolved. This article focuses on natural coastal protection approaches in England, where coastal management is governed by the Flood and Coastal Erosion Risk Management (FCERM) strategy published in 2020 [5]. While the Department for Environment, Food & Rural Affairs is responsible for steering the FCERM strategy via the Environment Agency, the plan is executed in collaboration with various local authorities, councils, and industry stakeholders, forming Risk Management Authorities [6]. Furthermore, FCERM strategy implementation takes place within the framework of local Shoreline Management Plans (SMPs), developed by local authorities and coastal management organizations in partnership with the Environment Agency. While not legally binding, SMPs aim to guide long-term, sustainable and cost-effective coastal policy action with a focus on accounting for natural processes of change [7,8]. This contrasts with the 19th and 20th century ad-hoc coastal management approach, which favoured the installation of engineered coastal defences such as sea walls and storm surge barriers, often triggered by extreme flood events [9].
The overarching objective of the current FCERM strategy is to enhance England’s resiliency to flooding and coastal erosion. Whilst the concept of coastal resilience is not well-defined in current policy documentation, definitions proposed in academic literature highlight the capacity of coastal systems to not only withstand but also recover from and adapt to disturbances such as continued sea level rise and extreme weather events [10,11,12]. This capacity for transformation enables a shift from traditional fixed engineered defences towards the implementation of more flexible nature-based schemes, able to adapt to uncertain and evolving future climate conditions [13,14].
Nature-based solutions (NbS)
In the context of coastal resilience, nature-based solutions (NbS) refer to interventions aimed at mitigating coastal hazards by leveraging the ability of marine habitats and/or landscape features to absorb wave energy, store flood waters and trap sediments [15,16,17]. In England, this natural approach to coastal management has so far predominantly focused on regenerating sand dunes [18] and restoring salt marshes [19,20,21]. Offshore green infrastructure such as oyster reefs, sea grass and kelp beds are increasingly being considered [22,23]. Depending on ecological, economical and social circumstances, NbS can either complement or replace more traditional man-made defences [24,25].
Strengths of nature-based solutions
Given uncertain climate projections, one of the key strengths of NbS is the ability of natural habitats to evolve with changing sea levels. For example, with sufficient sediment supply, intertidal habitats such as salt marshes can grow vertically, moving landward as sea levels rise [26,27], retaining their protective capability even with changing coastal conditions. Similarly, offshore green infrastructure grows as sea levels rise and the living structures can self-repair when damaged [28]. Thanks to their ability to adapt changing conditions, NbS require less maintenance than artificial coastal defences that need to be modified or replaced once design conditions are exceeded [29]. As a result, NbS can be more cost effective in the long term than engineered defences.
In addition to being cost efficient, ecosystem-based coastline protections offer environmental co-benefits. In the UK, sea grass beds have declined by nearly 40% since the 1980s [22]. This loss is particularly pronounced in Essex, where mapping study indicated that 1000 ha of salt marsh was lost in the 25-year period between 1973 and 1998 [30]. Restoration of these natural habitats as part of coastal management interventions can help restore ecosystems and reverse biodiversity loss by providing shelter to protected species [13,31]. Additionally, salt marsh vegetation, kelp forests and sea grass meadows can buffer ocean acidification [32,33,34] as well as serve as efficient carbon sinks [35,36]. Carbon sequestration capacity offered by marine vegetated habitats implies that coastal NbS can play an important role in accelerating the transition to carbon neutral policies.
Moreover, substituting or supplementing hard defences with natural features offers social advantages, such as enhanced well-being and recreational opportunities. Nature-focused coastal protection approaches can also positively impact the local economy through the creation of green jobs, new business opportunities, increased tourism, and a rise in property values [15]. It is noteworthy that these potential economic advantages are often overlooked by coastal communities, as highlighted by a recent EU-wide community survey [37].
Weaknesses of nature-based solutions
Unlike artificial defences constructed according to established design principles, natural habitats are dynamic systems. This poses challenges for computational modelling required for planning and managing the protection schemes. Additionally, the extent to which erosion and flood reduction capabilities of NbS are affected by factors such as vegetation type, plant species, sediment supply and habitat extent is not yet fully understood [38]. These uncertainties complicate the quantification of coastal resilience offered by proposed nature-based coastal protection schemes. However, research efforts to address these uncertainties and enhance the reliability of models are ongoing.
Another potential drawback of ecosystem-based coastal protection is the time delay between implementing the scheme and the establishment of flood and erosion risk mitigation functions. While data on the development timelines for marine habitats are limited, research indicates that it may take several years for the necessary properties to fully develop [39].
NbS implementation challenges
Hindrances to successful implementation
Securing funding for the implementation of coastal NbS presents administrative challenges. Traditional approaches to obtaining central government funding for FCERM interventions rely on a cost-benefit analysis framework, assessing costs against avoided economic losses (net benefits) over the project’s lifespan [40,41,42]. Originally designed for built protective infrastructure, this evaluation method inadequately accounts for the environmental, social and economic co-benefits associated with NbS [43], hindering their inclusion into funding plans. If a coastal project is deemed economically unfeasible based on the central government appraisal process, alternative funding sources such as local government allocations or private investment would need to be sought. However, securing private sector investment can be challenging due to the slow rate of implementation, the regulatory hurdles and the long investment timeframes associated with NbS projects [44].
Social acceptance can pose another obstacle to the implementation of NbS. While there is push towards nature-based schemes at national level, this preference is not consistently reflected at a local level [45,46]. Depending on perceived risks, awareness levels regarding how natural habitats mitigate flood and erosion risks, and timeline expectations, local communities may not fully support ecosystem-based coastal management approaches [47,48]. A recent multi-stakeholder study indicated that the inclination of certain local communities towards built defences may stem from a disconnection between people and ongoing coastal changes [49].
Opportunities for overcoming implementation challenges
Addressing the funding-related obstacles described above requires a revised framework for appraising FCERM projects based on their resilience-building capacity. The recommended approach would necessitate a standardised methodology for quantifying coastal resilience [50,51]. Additionally, it should consider the non-coastal protection benefits offered by NbS and capture the costs of flooding and erosion beyond just infrastructure and property losses 52,53]. To tackle the challenge of quantifying risks and benefits under uncertain climate scenarios, existing decision-making frameworks that account for uncertainty could be leveraged [54]. Furthermore, successful NbS case studies demonstrate that collaboration among government, academia, NGOs, and communities across multiple catchment areas is essential for effective implementation [55]. As such, developing coastal management funding mechanisms that foster partnerships could help alleviate current funding difficulties.
Drawing insights from the lessons learned in implementing complex socio-technical transitions in sectors such as energy, transport, and housing can provide valuable insights for overcoming social acceptance barriers to successful NbS implementation [56]. This entails early stakeholder engagement and participatory decision-making processes that consider local knowledge and perceptions [57]. Moreover, effective communication of the long-term vision for proposed NbS schemes, coupled with accessible evidence demonstrating their efficacy in coastal protection and associated co-benefits, is crucial for addressing community concerns, fostering trust, and ultimately gaining support from local communities [49].
References
[1] Wolf et al (2020). ‘Impacts of climate change on storms and waves relevant to the coastal and marine environment around the UK’, MCCIP Science Review 2020, pp. 132-157. https://doi.org/10.14465/2020.arc07.s
[2] Haigh et al (2020) ‘Impacts of climate change on coastal flooding, relevant to the coastal and marine environment around the UK’, MCCIP Science Review 2020, pp. 546–565. Available at: https://doi.org/10.14465/2020.arc23.cfl
[3] Masselink, G. and Russell, P. (2013) ‘Impacts of climate change on coastal erosion’, MCCIP Science Review 2013, pp. 71-86. DOI:10.14465/2013.arc09.071-086
[4] Committee on Climate Change. Managing the coast in a changing climate. 2018.
[5] Environment Agency. National Flood and Coastal Erosion Risk Management For England. 2020.
[6] Environment Agency. Flood and coastal erosion: risk management authorities. 2015.
[7] Nicholls et al (2013) ‘Planning for long-term coastal change: Experiences from England and Wales’, Ocean Engineering, 71, pp. 3–16. https://doi.org/10.1016/j.oceaneng.2013.01.025
[8] Pontee, N. I. and Parsons, A. (2012) ‘A review of coastal risk management in the UK’, Proceedings of the Institution of Civil Engineers – Maritime Engineering, 163(1), pp. 31–42. Available at: https://doi.org/10.1680/maen.2010.163.1.31
[9] Wadey et al (2015) ‘A comparison of the 31 January–1 February 1953 and 5–6 December 2013 coastal flood events around the UK’, Frontiers in Marine Science, 2. Available at: https://doi.org/10.3389/fmars.2015.00084
[10] Flood et al (2014) ‘The rise of resilience: Evolution of a new concept in coastal planning in Ireland and the US’, Ocean & Coastal Management, 102, pp. 19–31. Available at: https://doi.org/10.1016/j.ocecoaman.2014.08.015
[11] Masselink, G. and Lazarus, E. D. (2019) ‘Defining coastal resilience’, Water, 11(12). Available at: https://doi.org/10.3390/w11122587
[12] Rosati et al (2015) ‘Quantifying coastal system resilience for the US Army Corps of Engineers’, Environmental Systems and Decisions, 35, pp. 196–208. Available at: https://doi.org/10.1007/s10669-015-9548-3
[13] Morris et al (2018) ‘From grey to green: Efficacy of eco-engineering solutions for nature-based coastal defence’, Global Change Biology, 24, pp. 1827–1842. Available at: https://doi.org/10.1111/gcb.14063
[14] Stafford et al (2021) ‘Nature-based solutions for climate change in the UK: A report by the British Ecological Society’, British Ecological Society. Available at: https://www.britishecologicalsociety.org/policy/uk/nature-based-solutions/
[15] Hobbie, S. E. and Grimm, N. B. (2019) ‘Nature-based approaches to managing climate change impacts in cities’, Philosophical Transactions of the Royal Society, 375 (20190124). Available at: http://dx.doi.org/10.1098/rstb.2019.0124
[16] van der Meulen et al (2023) ‘Nature-based solutions for coastal adaptation management, concepts and scope, an overview’, Nordic Journal of Botany, 2023 (1). Available at: https://doi.org/10.1111/njb.03290
[17] Moraes et al (2022) ‘Nature-based solutions in coastal and estuarine areas of Europe’, Frontiers in Environmental Science, 10 (829526). Available at: https://doi.org/10.3389/fenvs.2022.829526
[18] Environment Agency & Defra. Joint Defra/EA Flood and Coastal Erosion Risk Management R&D Programme. 2007.
[19] Environment Agency. The extent and zonation of saltmarsh in England: 2016-2019. 2022.
[20] Fairchild et al (2021) ‘Coastal wetlands mitigate storm flooding and associated costs in estuaries’, Environmental Research Letters, 16(7). Available at: https://doi.org/10.1088/1748-9326/ac0c45
[21] Möller et al (2014) ‘Wave attenuation over coastal salt marshes under storm surge conditions’, Nature Geoscience, 7, pp. 727–731. Available at: https://doi.org/10.1038/ngeo2251
[22] Green et al (2021) ‘Historical analysis exposes catastrophic seagrass loss for the United Kingdom’, Frontiers in Plant Science, 12 (629962). Available at: https://doi.org/10.3389/fpls.2021.629962
[23] Morris et al (2019) ‘The application of oyster reefs in shoreline protection’, Journal of Applied Ecology, 56, pp. 1703–1711. Available at: https://doi.org/10.1111/1365-2664.13390
[24] Saleh, F. and Weinstein, M. P. (2016) ‘The role of nature-based infrastructure (NBI) in coastal resiliency planning: A literature review’, Journal of Environmental Management, 183, pp. 1088-1098. Available at: https://doi.org/10.1016/j.jenvman.2016.09.077
[25] Singhvi et al (2022) ‘The grey – green spectrum: A review of coastal protection interventions’, Journal of Environmental Management, 311 (114824). Available at: https://doi.org/10.1016/j.jenvman.2022.114824
[26] Kirwan et al (2016) ‘Overestimation of marsh vulnerability to sea level rise’, Nature Climate Change, 6, pp. 253–260. Available at: https://doi.org/10.1038/nclimate2909.
[27] Schuerch et al (2018) ‘Future response of global coastal wetlands to sea-level rise’, Nature, 561, pp. 231–234. Available at: https://doi.org/10.1038/s41586-018-0476-5.
[28] Ferrario et al (2014) ‘The effectiveness of coral reefs for coastal hazard risk reduction and adaptation’, Nature Communications, 5 (3794). Available at: https://doi.org/10.1038/ncomms4794.
[29] Vuik et al (2019) ‘Salt marshes for flood risk reduction: Quantifying long-term effectiveness and life-cycle costs’, Ocean & Coastal Management, 171, pp. 96–110. Available at: https://doi.org/10.1016/j.ocecoaman.2019.01.010.
[30] Cooper et al (2001) ‘25 years of salt marsh erosion in Essex: Implications for coastal defence and nature conservation’, Journal of Coastal Conservation, 7(1). Available at: http://www.jstor.org/stable/25098347.
[31] Temmerman et al (2013) ‘Ecosystem-based coastal defence in the face of global change’, Nature, 504, pp. 79–83. Available at: https://doi.org/10.1038/nature12859.
[32] Bergstrom et al. (2019) ‘Seagrass can mitigate negative ocean acidification effects on calcifying algae’, Scientific Reports, 9 (1932). Available at: https://doi.org/10.1038/s41598-018-35670-3.
[33] Young et al (2022) ‘Kelp (Saccharina latissima) mitigates coastal ocean acidification and increases the growth of North Atlantic bivalves in lab experiments and on an oyster farm’, Frontiers in Marine Science, 9 (881254). Available at: https://doi.org/10.3389/fmars.2022.881254.
[34] Reithmaier et al (2023) ‘Carbonate chemistry and carbon sequestration driven by inorganic carbon outwelling from mangroves and saltmarshes’, Nature Communications, 14 (8196). Available at: https://doi.org/10.1038/s41467-023-44037-w.
[35] Bedulli et al. (2020) ‘Contribution of seagrass blue carbon toward carbon neutral policies in a touristic and environmentally-friendly island’, Frontiers in Marine Science, 7(1). Available at: https://doi.org/10.3389/fmars.2020.00001.
[36] Himes-Cornell et al (2018) ‘Valuing ecosystem services from blue forests: A systematic review of the valuation of salt marshes, seagrass beds, and mangrove forests’, Ecosystem Services, 30, pp. 36–48. Available at: https://doi.org/10.1016/j.ecoser.2018.01.006.
[37] Faivre et al (2017) ‘Nature-Based Solutions in the EU: Innovating with nature to address social, economic and environmental challenges’, Environmental Research, 159, pp. 509–518. Available at: https://doi.org/10.1016/j.envres.2017.08.032
[38] Jordan, P. and Fröhle, P. (2022) ‘Bridging the gap between coastal engineering and nature conservation?’, Journal of Coastal Conservation, 26 (4). Available at: https://doi.org/10.1007/s11852-021-00848-x
[39] Short et al (2000) ‘Developing success criteria for restored eelgrass, salt marsh and mud flat habitats’, Ecological Engineering, 15(3–4), pp. 239–252. Available at: https://doi.org/10.1016/S0925-8574(00)00079-3
[40] Environment Agency. A review of skills and guidance in flood and coastal risk management benefit cost assessment ‘ Appendix B. 2021.
[41] House of Commons Library. Flood risk management and funding. 2024.
[42] Penning-Rowsell EC, Johnson C, Tunstall SM, et al. Flood and coastal erosion risk management: A manual for economic appraisal. London: Routledge; 2014.
[43] Dittrich et al (2019) ‘A cost-benefit analysis of afforestation as a climate change adaptation measure to reduce flood risk’, Journal of Flood Risk Management, 12 (12482). Available at: https://doi.org/10.1111/jfr3.12482
[44] European Investment Bank. Investing in nature-based solutions: state-of-play and way forward for public and private financial measures in Europe. 2023.
[45] Anderson et al. (2022) ‘Green, hybrid, or grey disaster risk reduction measures: What shapes public preferences for nature-based solutions?’, Journal of Environmental Management, 310 (114727). Available at: https://doi.org/10.1016/j.jenvman.2022.114727
[46] Apine, E. and Stojanovic, T. (2024) ‘Is the coastal future green, grey or hybrid? Diverse perspectives on coastal flood risk management and adaptation in the UK’, Cambridge Prisms: Coastal Futures, 2, pp. 1–13. Available at: https://doi.org/10.1017/cft.2024.4
[47] Cotton et al (2022) ‘Understanding perceived effectiveness of a novel coastal management project: The case of the Bacton-Walcott sandscaping scheme, UK’, Frontiers in Marine Science, 9 (1028819). Available at: https://doi.org/10.3389/fmars.2022.1028819
[48] Josephs, L. I. and Humphries, A. T. (2018) ‘Identifying social factors that undermine support for nature-based coastal management’, Journal of Environmental Management, 212, pp. 32–38. Available at: https://doi.org/10.1016/j.jenvman.2018.01.085
[49] Brown et al (2023) ‘Transitions in modes of coastal adaptation: addressing blight, engagement and sustainability’, Frontiers in Marine Science, 10 (1153134). Available at: https://doi.org/10.3389/fmars.2023.1153134
[50] Townend et al (2021) ‘Operationalising coastal resilience to flood and erosion hazard: A demonstration for England’, Science of The Total Environment, 783. Available at: https://doi.org/10.1016/j.scitotenv.2021.146880
[51] Rouleau et al (2022) ‘The climate and ocean risk vulnerability index: Measuring coastal city resilience to inform action’, Frontiers in Sustainable Cities, 4 (884212). Available at: https://doi.org/10.3389/frsc.2022.884212
[52] Mulchandani et al (2020) ‘The English national cohort study of flooding & health: Psychological morbidity at three years of follow-up’, BMC Public Health, 20 (321). DOI: 10.1186/s12889-020-8424-3
[53] Yesodharan et al (2021) ‘The lived experience of victims of catastrophic coastal erosion: A cycle of impact, consequence, and recovery’, Sultan Qaboos University Medical Journal (SQUMJ), 21, pp. 94-102. DOI: 10.18295/squmj.2021.21.01.013
[54] Dessai et al (2007) ‘Assessing the robustness of adaptation decisions to climate change uncertainties: A case study on water resources management in the East of England’, Global Environmental Change, 17, pp. 59–72. Available at: https://doi.org/10.1016/j.gloenvcha.2006.11.005
[55] Short, C. (2015) ‘Micro-level crafting of institutions within integrated catchment management: Early lessons of adaptive governance from a catchment-based approach case study in England’, Environmental Science & Policy, 53, pp. 130–138.
[56] Geels, F. W. (2019) ‘Socio-technical transitions to sustainability: A review of criticisms and elaborations of the multi-level perspective’, Current Opinion in Environmental Sustainability, 39, pp. 187–201. Available at: https://doi.org/10.1016/j.cosust.2019.06.009
[57] Haughton et al (2015) ‘In search of ‘lost’ knowledge and outsourced expertise in flood risk management’, Transactions of the Institute of British Geographers, 40, pp. 375–386. Available at: https://doi.org/10.1111/tran.12082
About the Author
Joséphine Anselin
Joséphine Anselin is an Applied Mathematics PhD Researcher at the University of Cambridge. She is interested in the interplay between climate science and policy, particularly in the context of coastal adaptation. Prior to starting her PhD, Joséphine worked as an Engineer in the energy industry and then as a Strategy Consultant. She holds an MEng in Engineering Science from the University of Oxford and an MSc in Physical Oceanography from Bangor University.
ORCID: https://orcid.org/0000-0003-4057-3869
Corresponding address: ja754@cam.ac.uk
Confilct of interest: The author declares no conflict of interest.