The threat to Italy’s extensive coastline results from a destructive combination of global climate change and local geological instability. Understanding the future of the Italian coast requires separating the effects of rising oceans from the sinking of the land itself. This interaction, which scientists call relative sea level rise, is accelerating the vulnerability of densely populated and culturally significant coastal areas across the peninsula.
Distinguishing Sea Level Rise from Land Subsidence
Eustatic sea level rise is the global component, driven by the thermal expansion of ocean water as it warms and the melting of continental ice sheets and glaciers. This worldwide rise affects all of Italy’s approximately 8,300 kilometers of coastline uniformly. However, local land subsidence dramatically multiplies this impact in certain regions, creating a highly variable threat profile.
Land subsidence refers to the gradual sinking of the ground surface, occurring for a mix of natural and human-induced reasons. Naturally, some coastal areas, particularly river deltas, settle as soft sediments compact under their own weight. This is especially true for the Po River Delta on the Adriatic coast.
Human activities exacerbate this natural sinking, primarily through the historical over-extraction of groundwater and natural gas. This removes underlying support and causes the land to compact more quickly. The combination of global sea rise and local land sinking results in a much faster rate of relative sea level rise. This effect is not uniform; some volcanic areas, such as near Naples, are experiencing land uplift at a rate of about 9.5 millimeters per year, which locally counters the global sea level increase.
The Most Vulnerable Regions and Current Impact
The consequences of this dual threat are most visible along the northern Adriatic coast, particularly the Po Delta and the Venice Lagoon, which have historically experienced high subsidence rates. Venice is the most famous example, where the frequency of acqua alta, or high water events, has increased dramatically. Since 1966, the city has recorded nearly 300 tides measuring over 110 centimeters, compared to only 47 such events in the previous fifty years.
The impact is also severe across the Tyrrhenian and southern coasts, contributing to widespread coastal erosion that affects beaches and infrastructure. Low-lying coastal plains in regions like Friuli Venezia-Giulia, Veneto, Emilia-Romagna, and sections of the Tyrrhenian coast in Tuscany and Lazio are identified as high-risk zones. In the south, the Tavoliere delle Puglie plain is subsiding at rates up to 7.5 millimeters per year in some spots, accelerating shoreline retreat.
Coastal erosion has led to significant land loss, threatening economic sectors like tourism and agriculture. In parts of southern Sicily, satellite imagery has recorded coastal retreat up to 70 meters in recent decades. The loss of beaches impacts tourism and removes the natural buffer that protects inland infrastructure from storm surges and high tides.
Major Protective Measures and Adaptation Strategies
Italy’s most visible response to the rising sea is the MOSE (Modulo Sperimentale Elettromeccanico) project in Venice. This vast engineering system consists of 78 mobile barrier gates installed at the three inlet mouths connecting the Venetian Lagoon to the Adriatic Sea. The gates lie flat on the seabed when inactive but are raised by injecting compressed air, effectively sealing the lagoon during exceptionally high tides.
The MOSE system is activated when a tide forecast exceeds 1.30 meters, protecting the city from potential floods up to 3 meters high. Since becoming operational in October 2020, the barriers have been raised approximately 25 times per year to protect the city center from acqua alta. While highly effective at flood defense, the system’s frequent use presents a complex challenge for the delicate lagoon ecosystem, as it restricts the natural exchange of water and sediment.
Beyond this massive infrastructure project, other coastal zones rely on varied adaptation strategies. Many areas employ beach nourishment, which involves dredging sand from offshore and depositing it on eroded beaches to restore the natural coastal buffer. Hard defenses, such as seawalls and jetties, are also used to protect specific infrastructure. Policy changes are also being implemented to guide land-use planning, restricting new construction in the most vulnerable coastal flood zones to prevent future risk.
Future Projections for Italian Coasts
Scientific models project a significant increase in the vulnerability of Italy’s coasts if current climate trends continue. By 2050, approximately 20% of Italy’s beaches could be lost due to sea level rise, coastal erosion, and increased flooding. In a worst-case scenario, this land loss could increase to 40% of the coastline by 2100.
Regions already experiencing high subsidence, such as the Po Delta, are projected to face a relative sea level rise up to 1.1 meters higher than the average global projection by 2100. This means that up to 5,500 square kilometers of low-lying coastal plains could be exposed to inundation by the end of the century. The economic implications of this projected land loss are substantial, impacting half of the country’s port infrastructure and a significant portion of its agricultural land.