Climate change and nature based solutions against coastal floods in Europe
According to the 2023 Blue Economy Report, coastal flooding currently causes economic damages of € 1.2 billion per year in the EU. To put this into perspective, this amount is roughly one sixth of the total budget allocated to the European Maritime, Fisheries and Aquaculture Fund (EMFAF). Additionally, approximately 72 000 people in the EU are affected by coastal flooding each year. If coastal protection measures remain unchanged, the economic impact of coastal flooding is expected to increase significantly due to global warming, affecting all Member States with a coastline. By 2100, annual damages could reach €1 trillion, with 3.9 million people exposed to coastal flooding every year in Europe. Between € 137 billion (moderate-emission scenario) to € 814 billion (high-emission scenario) of these annual damages could take place in the EU, depending on the severity of climate change.
Regarding investments and climate financing, the average annual cost of adaptation for the EU-27 is estimated at €1.8 billion per year under a high emissions scenario and €1.1 billion per year under a moderate mitigation scenario for 2020-2100. Notably, the cost of enhancing coastal protection is considerably lower than the potential reduction in annual flood losses by the end of the century. This highlights the substantial and increasing long-term benefits of investing in coastal protection now, demonstrating that spending on adaptation and coastal defence in the EU is highly cost-effective.
As climate change accelerates the rise in sea levels and intensifies coastal hazards, societies will actively adapt to protect assets and livelihoods from flooding and erosion. Nature Based Solutions (NBS) have been gaining increasing attention as a resilient and adaptable strategy for safeguarding coastlines. Compared with traditional engineering approaches, they can be more sustainable and cost-effective, leveraging natural processes and ecosystems such as wetlands, mangroves, dunes, and reefs, to reduce the impacts of coastal flooding and erosion while simultaneously enhancing biodiversity and supporting local communities. By integrating ecological restoration with human infrastructure needs, these approaches not only provide physical protection but also contribute to carbon sequestration, water quality improvement, and recreational opportunities, making them a holistic solution for coastal resilience.
Current state of Nature-based solutions practice
Evidence from Europe shows that most NBS projects were implemented from 2002 onwards, with a significant increase between 2005 and 2015. The Netherlands and the United Kingdom have the most documented case studies, with public funding being the most common source. Although 81% of case studies reported monitoring efforts, more than half did not provide information on flood or erosion effectiveness. Nonetheless, many NBS projects report multiple co-benefits, including biodiversity conservation, recreation, flood reduction, and tourism.
Bioinspired design also plays a role in developing NBSs, utilising problem-based and solution-based approaches. While many studies report positive outcomes, some findings indicate negative, neutral, or mixed results, particularly in terms of sediment and morphology. This highlights that NBSs may not always fully achieve coastal protection goals, highlighting the need for ongoing research and adaptive management.
Nature-based solutions in view of rising seas from a European perspective
Coastal adaptation pathways typically include three main strategies: protect, accommodate, and retreat. Protection involves constructing physical barriers to defend against coastal flooding and erosion, thus safeguarding human settlements and infrastructure. Accommodating means adjusting human activities and infrastructure to adapt to changing coastal conditions, for example elevating buildings and enhancing drainage systems to manage flood risks. Retreating involves the strategic relocation of people, assets, and infrastructure away from vulnerable coastal areas to safer inland locations, allowing natural coastal processes to occur without human interference.
NBSs often involve a loose combination of the three strategies. Some level of retreating is necessary to generate space so that natural elements can offer their protective services. Further, when NBSs are applied, the capacity of a given area to accommodate flooding increases, and in many cases NBSs offer protection, absorbing the energy of storms and even acting as a natural block to floods. The methodology for assessing the costs and benefits of NBS projects has recently become better formalised, and several cases studies even report benefits exceeding the costs by more than five times.
Europe’s coastline is remarkably diverse, characterised by significant variations in wave energy, tidal range, and storm exposure. Along the Atlantic coast, powerful waves generated by the North Atlantic Ocean influence regions such as the west coasts of France, Ireland and Portugal, creating high-energy environments ideal for dynamic coastal landforms like cliffs and sandy beaches. In contrast, the Mediterranean coastline experiences relatively lower wave energy due to its enclosed basin, resulting in calmer waters and more sheltered coastal features. Tidal ranges also vary widely across Europe, from extreme tidal fluctuations exceeding 10 metres in the United Kingdom (e.g. the Severn Estuary) to minimal tidal changes in the Mediterranean Sea. In addition, Europe’s coastlines face diverse storm patterns, with frequent and intense winter storms affecting the Atlantic and North Sea coasts, whereas the Mediterranean is more prone to shorter, more intense rainstorms and occasional ‘medicanes’ (Mediterranean hurricanes). This complex interplay of waves, tides, and storms shapes Europe’s coastal landscapes and influences its ecosystems, and as a result defines the nature of adequate NBS approaches at each region.
Wave-dominated coastlines require structures strong enough to sustain the impact of waves, and therefore soft vegetation cannot offer any substantial protection. This implies that salt marshes and sea grass meadows could mainly serve as a complementary, ‘second line of defense’, behind beaches and other protective structures, or in estuaries. Coral reefs can dissipate waves but their species cannot survive in Europe’s conditions. The same can be said for mangroves, and as a result both could be possible avenues to explore in the outermost regions of continental Europe or overseas territories.
Data shows that, worldwide, only a small part of the coastline is protected by vegetation and coral reefs, and there is a clear tendency for natural sandy beaches to be replaced by managed ones. Europe’s coastline is densely populated and has already undergone several interventions, losing its natural protective capacity. The discussion above indicates that well-planned interventions are needed, rather than ‘leaving nature alone to act’.
In previous Blue Economy Reports we reported clear economic motivations for investing in coastal adaptation, as the benefits of immediate action outweighed the costs, even when high discount rates were considered. The previous analyses were based on unit cost values for traditional interventions providing coastal protection, which are expected to be slightly lower than those for NBSs. However, our previous estimates entail a high range of uncertainty, so the previous conclusion of undisputed economic motivation for adaptation also applies to the case of NBSs, especially in the parts of the European coastline that hosts built-up areas. This conclusion is justified by existing studies, which report that the benefits of NBSs outweigh the costs by at least three times.