Coastal Flood Risk to European Surface Transport Infrastructure at Different Global Warming Levels
- Jun 10
- 6 min read
A 2026 study finds coastal flooding already costs Europe €519M/year in transport damage, rising to €1.09B at 4°C, with roads most exposed and rail most expensive to repair.
Europe's transport network is a coastal network. Roads and railways hug shorelines, thread through low-lying deltas, and connect port cities that have grown precisely because they sit at the water's edge. This geographic intimacy with the sea, which has long been an economic asset, is rapidly becoming a liability.
As sea levels rise and extreme coastal flood events intensify with global warming, the infrastructure that carries passengers, freight, and supply chains across the continent faces growing exposure to damage — yet no comprehensive, probabilistic assessment of that risk had previously been attempted at the European scale, for both road and rail, across a range of warming scenarios.
Nawarat et al. (2026) fill this gap directly, integrating coastal flood hazard projections with the full road and rail network of Europe to quantify expected annual damages from the current climate baseline through to 4°C of global warming, country by country and infrastructure type by infrastructure type.
Key Findings
A Probabilistic Framework Across Five Warming Levels
The study constructs a fully probabilistic risk assessment by combining three components: coastal flood hazard maps generated by the process-based hydraulic model LISFLOOD-ACC for extreme sea level return periods of 1 to 1,000 years at each warming level; road and rail network data from OpenStreetMap, classified into five road types (motorway, trunk, primary, secondary, tertiary) and three rail types (high-speed, conventional electrified, conventional non-electrified); and type-specific depth-damage curves and reconstruction cost estimates, including uncertainty ranges reflecting flood velocity conditions and cross-country construction cost variation.
Risk is reported as two metrics: expected annual damage (EAD) in euros per year, representing the probability-weighted average loss across all flood return periods; and expected annual length affected (EALA) in kilometres per year, capturing the physical extent of network disruption. Both are calculated for a 1980–2020 baseline and for global warming levels of 1.5°C, 2°C, 3°C, and 4°C relative to pre-industrial conditions. For each road and rail segment, 1,000 EAD samples are generated to propagate uncertainty through to national and continental aggregates.
Baseline Damage Is Already Substantial — and Roads Bear the Brunt
Under baseline (1980–2020) climate conditions, 1,592 km of Europe's road and rail networks are affected by coastal flooding annually, generating a median expected annual damage of €519 million [5th–95th percentile range: €318 million–€722 million]. Roads dominate the affected length in all but two European countries (Latvia and Slovenia), primarily because European road networks have a substantially greater extent within the low-elevation coastal zone — defined as areas at or below 10 m above mean sea level — than rail networks.
The largest baseline EALA by country is in Italy (436 km), the UK (355 km), France (195 km), Norway (100 km), and Denmark (94 km). Notably, these high values are not straightforwardly explained by the amount of low-elevation coastal land: Norway has relatively little low-elevation coastal zone per kilometre of coastline, yet ranks fifth due to the high percentage of its national transport network situated within that zone (8.1%). The UK, similarly, has 8% of its national network in the low-elevation coastal zone versus France's 3% — a difference that accounts for the UK's much higher EALA despite both countries having nearly identical LECZ areas per kilometre of coastline.
Railways Are Cheaper to Flood, More Expensive to Fix
Despite roads accounting for the larger share of physically affected network length, rail infrastructure dominates the economic damage picture. Under baseline conditions, conventional non-electrified rail alone accounts for €275 million of the total €519 million EAD — roughly half the continental total — because railway reconstruction costs are substantially higher per kilometre than road reconstruction costs. This dominance of rail in the EAD, relative to roads in the EALA, grows stronger at higher warming levels, reflecting the compounding economic weight of rail damage as flood extents expand.
Every Fraction of Warming Increases Damage Across the Continent
With 1.5°C of warming, the Europe-wide EALA increases by approximately 60% from baseline to 2,542 km, and the median EAD rises to €818 million [€530 million–€1,108 million] — a 58% increase. At 2°C, the EALA reaches 2,648 km (66% above baseline) and the median EAD climbs to €844 million. At 3°C, the median EAD reaches €1,002 million (93% above baseline), and at 4°C it rises to €1,090 million [€695 million–€1,487 million], more than doubling the median baseline figure. There is no warming level at which any European country escapes increased damage — EAD rises with global temperature in every country across every scenario examined.
The countries facing the largest relative increases in EAD — particularly Cyprus, Bulgaria, France, Croatia, and Romania — are not necessarily those with the highest absolute baseline damages. Cyprus is the most striking case: its baseline EAD is modest, but the study projects a tenfold increase at just 1.5°C, rising to a 23-fold increase at 4°C. Small economies can thus face disproportionate relative burdens even when absolute damage figures appear modest by comparison with larger countries.
The Road Dependence Problem in Coastal Transport
A particularly concerning cross-cutting finding concerns the modal structure of transport in Europe's low-elevation coastal zone. Passenger and haulage transport in these areas is overwhelmingly road-dependent in the vast majority of European countries — and it is roads that are more physically exposed to coastal flooding in almost every country. This creates a structural vulnerability: if coastal flooding disrupts road networks and those networks carry the dominant share of coastal passenger and freight transport, the indirect and cascading socio-economic costs of flooding events could substantially exceed the direct reconstruction damage quantified here. The study identifies this road dependence as a major risk amplifier unless significant modal shifts occur or infrastructure relocates away from the coastal zone.
What the Numbers Mean for Transport Budgets
Beyond the aggregate damage projections, the study directly confronts the question of what these figures mean for national transport expenditure planning:
The UK faces the largest absolute adaptation burden: Under baseline conditions, the UK's EAD of €272 million — more than half the entire European total — already represents a significant share of its national surface transport budget. At 1.5°C, an additional €155 million per year in transport expenditure would be needed to cover the increase in coastal flood damage; at 4°C, that figure rises to €263 million annually.
Denmark, Ireland, and the UK face the highest EAD-to-transport-budget ratios: Denmark's baseline EAD already constitutes 1.5% of its total annual surface transport expenditure, rising to 2.3% at 1.5°C. For smaller economies already spending heavily relative to GDP on transport, even modest absolute increases in flood damage represent meaningful fiscal pressure.
Some countries face a forced reallocation between road and rail: In Croatia, road damage currently dominates the total EAD, but at 2°C, rail damage is projected to surpass it — potentially requiring a reallocation of transport expenditure toward rail at the expense of roads, even though road transport dominates coastal passenger and freight activity. The reverse dynamic applies in Bulgaria, where a shift from rail-dominated to road-dominated damage at 2°C may require redirecting funding toward roads. France faces similar cross-sector realignment pressures. These forced reallocations create governance challenges distinct from the overall scale of expenditure increase.
All projections represent a no-adaptation lower bound: The EAD estimates are based on current static infrastructure without accounting for future network expansion into coastal zones, which is likely given ongoing TEN-T development, or for the possibility that adaptation investment continues to lag. Both factors imply the true future costs could exceed the projections presented here.
Infrastructure at the Water's Edge
Europe has built its transport arteries where commerce has always flowed — along coasts, through estuaries, into port cities — and now the sea is encroaching on that inheritance. Nawarat et al.'s study makes clear that the cost of this encroachment is already measured in hundreds of millions of euros per year, and that it will grow with every fraction of a degree of warming regardless of which country bears it. The road network, which carries most of the freight and passengers moving through Europe's coastal zones, is also the most physically exposed — creating a compounding vulnerability that goes well beyond the direct reconstruction costs assessed here. As the TEN-T network expands into coastal regions with one hand, the other will need to be busy climate-proofing what already exists. The choice is not whether to spend more on coastal transport resilience, but how soon and how strategically.
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