Rising sea levels pose a major threat to Venice, Italy. Known for its old structures, layers of history, and unique ties to the water, Venice faces increasing risks of major flooding and damage due to both rising sea levels and subsidence. Studies show a range of future projections for sea-level rise in Venice, with the likely outcome by 2100 being a rise of 21–52 cm. Low elevation, proximity to the Venice lagoon, and the city's series of canals make it particularly vulnerable to sea level changes. Flooding is a frequent and damaging disruption that poses threats to cultural heritage, biodiversity, public health, and tourism. Venetians have implemented measures to mitigate these changes, such as glass barriers, elevating lower lying areas of the city, and MOSE, a series of floodgates to protect the lagoon from high tides. Research paints a troubling picture for the future of the city and its surrounding areas if current climate trends continue or intensify.
History Since the 1990s Venice has experienced changes in relative sea level. This has been driven by a combination of global sea-level rise and local subsidence caused by tectonic plates shifting near the Italian coast. Between 1993 and 2019, tide-gauge measurements in Venice, after correcting for subsidence, indicate an average sea-level rise of approximately 2.76 ± 1.75 mm per year. This rate is higher than the historical trend observed between 1872 and 2019, which was estimated at 1.23 ± 0.13 mm per year. Venetian sea level is linked to broader Mediterranean and Adriatic Sea trends, which are influenced by oceanic and atmospheric dynamics. The exchange of water through the Strait of Gibraltar is one factor contributing to uncertainties in regional sea-level rise projections. Short-term fluctuations in atmospheric pressure variations, storm surges, and tidal cycles also exacerbate the flooding events. Sea-level rise has already affected Venice and will continue to challenge the city. The frequency and intensity of acqua alta (high water events) have increased. This has led to disruptions in daily life, damage to infrastructure, and a greater need for adaptive measures. In response, large-scale engineering projects like the MOSE (Modulo Sperimentale Elettromeccanico) barrier system have been developed to protect the city from extreme flooding. While these efforts have provided temporary relief, continued sea-level rise and ongoing subsidence remain pressing concerns for the long-term sustainability of Venice.
Economic consequences The MOSE system (Modulo Sperimentale Elettromeccanico) is a series of mobile gates designed to protect Venice and its lagoon from high tides. The cost of the MOSE system has exceeded €6 billion. The benefits of the MOSE system are expected to outweigh the expenses, as it has provided protection against flooding. The operation and maintenance of MOSE are expensive, adding a perpetual financial burden onto the city. The implementation of the MOSE system also incurs direct costs on ship traffic, ranging from €348,000 to €1.3 million, due to longer wait times for harbor access. While these costs impact port activities, they are considered minor compared to the broader benefits the system provides to the city.
Tourism
Increased flooding also has a negative impact on tourism. Indirect losses arise from decreased tourism and regular disruptions to daily life. The November 2019 flood was particularly devastating. It caused extensive damage, fatalities, and highlighted the need for frequent and costly interventions. As a result hotel prices tend to decrease when there is a greater chance of flooding, further impacting the tourism sector. The damage to historic buildings and cultural heritage is another concern. Saltwater intrusion and rising damp are threats to Venice's unique architectural and cultural heritage. Preservation and restoration efforts are expensive and also challenging with more frequent and severe flooding. This vulnerability compounds the tourism concerns. The canals on which many historic structures are built contain stairways that provided access to waterways. These buildings often included waterproofed basements designed to mitigate water intrusion. Recent increases in sea levels have rendered many of these traditional flood-prevention methods insufficient. Several historical sites have already suffered damage due to the rising tides. This deterioration has affected cultural landmarks such as the Teatro La Fenice opera house and the Cathedral of Murano. In addition to water damage, the accumulation of salt accelerates the degradation of building materials. Indoor monuments not directly exposed to flooding are falling apart due to increased moisture and repeated wetting. While building codes continue to be updated to ensure new constructions are more resilient, existing historical structures remain vulnerable to increasing environmental threats.
Impact on infrastructure
Sewage systems Venice's sewage systems are threatened by sea level rise through the increase in saltwater intrusion and back flow issues. With higher sea levels saltwater can penetrate further into the sewage system, disrupting its functionality and increasing the risk of contaminating freshwater. During high tide events, the system can become overwhelmed, which leads to overflows. Overflows contribute to pollution in both the lagoon and the city streets, posing public health risks.
Building foundations Saltwater intrusion weakens building foundations over time, contributing to structural instability. This is problematic in Venice, where many buildings were and are constructed using porous materials such as brick and limestone, which readily absorb saltwater. The absorption of saltwater accelerates the deterioration of these materials, causing erosion. The costs associated with maintaining and restoring, preserving, and maintaining historic structures are increasing. More frequent flooding compounds these issues.
Adaptation measures
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