St. Mark’s Basilica has survived more than a thousand years of floods, wars, and sinking foundations. But a peer-reviewed study now projects that the basilica and much of Venice’s historic center could face near-permanent submersion by the middle of the next century if greenhouse gas emissions are not sharply reduced.
The research, led by Davide Masin and colleagues at the University of Padua and published in the journal Remote Sensing, maps relative sea-level rise across 11 zones of the Venice Lagoon at three future time horizons: 2050, 2100, and 2150. By combining satellite measurements of land subsidence with global sea-level projections from the IPCC Sixth Assessment Report, the authors show that parts of the lagoon are sinking at the same time the Adriatic is climbing, and that the combined effect threatens to overwhelm the city’s existing defenses.
The findings arrive as Venice’s MoSE flood barrier system, first activated in October 2020 and regularly operational since 2021, faces questions about its long-term viability. The barriers were engineered to block storm surges, not to hold back a slow, relentless rise in baseline water levels. If average sea level climbs high enough, the gates would need to close so frequently that port traffic and lagoon ecology would be disrupted, effectively making the system impractical for daily use.
What the projections show
The study’s core method layers locally measured subsidence rates on top of global climate projections to calculate relative sea-level rise, or RSLR, the metric that determines whether a given site stays dry or goes under. The researchers drew on three data streams: vertical land motion tracked by GNSS positioning and InSAR radar interferometry, high-resolution ground elevation from LiDAR terrain models, and sea-level trajectories tied to the IPCC’s Shared Socioeconomic Pathways, which range from aggressive decarbonization to continued heavy fossil-fuel use.
By 2050, under most scenarios, Venice faces a sharp increase in “acqua alta” high-water events rather than outright submersion. By 2100, high-emission pathways produce RSLR large enough that today’s exceptional tides could become routine. By 2150, the study’s maps show extensive portions of the historic center and surrounding lagoon lying below mean water level under the worst-case pathway, with only artificial barriers standing between the city and the sea.
The gap between futures is stark. Under low-emission scenarios, Venice would still contend with worsening floods but could plausibly adapt through raised pavements, improved drainage, and continued barrier operations. Under high-emission scenarios, adaptation of that kind would be overwhelmed. The difference hinges on global policy decisions made far from the lagoon.
Subsidence makes the problem worse, and uneven
One of the study’s most important findings is that RSLR is not uniform across the lagoon. Some zones are subsiding faster than others due to underlying geology and decades of past groundwater extraction, meaning they effectively experience a higher rate of sea-level rise than neighboring districts. Low-lying marshes and barrier islands face chronic inundation first, followed by sections of the historic center as baseline water levels climb.
That spatial variability complicates planning. Defenses calibrated for one sector of the lagoon may be inadequate just a few kilometers away. The study’s 11-zone breakdown is designed to capture these differences, though the authors note that subsidence rates can shift over short distances, and their zone-level averages may not reflect conditions at individual buildings or infrastructure sites.
A preview from 2019
What high water already does to Venice is well documented. A separate study published in Scientific Reports analyzed the November 2019 acqua alta, when water reached 187 centimeters at the Punta della Salute tide gauge, the second-highest level recorded since systematic measurements began in 1872. Only the catastrophic flood of November 1966, at 194 cm, was worse.
That 2019 event caused widespread damage to basilicas, shops, and homes across the city. The Scientific Reports analysis uses Venice’s long tide-gauge record, one of the most continuous water-level datasets in the world, to show how the frequency and intensity of such extremes have shifted over time. Under the RSLR trajectories mapped in the Remote Sensing study, events of that magnitude could move from once-in-a-generation crises to seasonal occurrences by the late 21st century.
What remains uncertain
The projections carry significant uncertainty, particularly beyond 2100. Ice-sheet dynamics in Greenland and Antarctica remain difficult to model, and the possibility of rapid ice-shelf collapse could push sea levels well above median estimates. The Remote Sensing study accounts for this by presenting multiple scenarios with wide uncertainty bands rather than a single forecast, but the outer bounds of those projections are not hypothetical extremes. They reflect physical processes that glaciologists have observed accelerating in recent years.
On the engineering side, no peer-reviewed assessment of MoSE’s post-2020 performance record has been published. Discussion of next-generation defenses has surfaced in Italian news coverage, but no official timeline, design, or budget for a successor system has been made public as of May 2026.
Human decisions add another layer of unpredictability. Investments in raised infrastructure, redesigned drainage, or additional barriers could significantly reduce flooding in specific neighborhoods. Delayed maintenance or underfunded defenses could make outcomes worse than any model projects. Neither study attempts to simulate those governance choices, leaving a wide band between what is technically possible and what political will actually delivers.
What is at stake beyond the stones
Venice draws roughly 30 million visitors a year, and its tourism-dependent economy is already strained by repeated flooding, population decline, and the costs of maintaining fragile historic structures in a corrosive saltwater environment. The city’s resident population in the historic center has fallen below 50,000, a fraction of its mid-20th-century peak, and each major flood event accelerates the departure of families and small businesses.
The RSLR projections add a timeline to a threat that Venetians have lived with for generations. Under low-emission pathways, the city faces decades of difficult but potentially manageable adaptation. Under high-emission pathways, the question shifts from how to protect Venice to whether large parts of it can be protected at all. The science does not answer that question, but it narrows the window in which the answer remains a choice rather than a foregone conclusion.
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*This article was researched with the help of AI, with human editors creating the final content.
