Galveston is not expected to be fully submerged by a single dramatic event, but the island is losing ground to the sea faster than almost any other place on the U.S. coastline. Sea levels around Galveston have risen about 71 centimeters (roughly 2.3 feet) since 1904, and under higher-end projections, an additional 2.5 feet of rise is possible by 2100. The real question isn’t whether Galveston will be “underwater” on some future date. It’s how quickly flooding becomes frequent enough that normal life on the island becomes unsustainable.
How Fast the Water Is Rising
NASA’s sea level projections for Galveston show a range of outcomes depending on how aggressively global emissions are reduced. By 2050, the island faces roughly half a foot of additional rise above year-2000 levels across all scenarios, from 0.46 feet in the most optimistic case to 0.67 feet in the highest. The differences become dramatic by 2100: the low scenario adds just 0.85 feet, while the high scenario adds 2.5 feet.
The observed trajectory, based on actual measurements so far, tracks at about 0.58 feet by 2050, landing between the intermediate and intermediate-high scenarios. That trajectory suggests the island is not on the most optimistic path. At the current measured rate of 6.51 millimeters per year, Galveston is experiencing sea level rise roughly twice the global average.
Why Galveston Is Sinking, Not Just Flooding
What makes Galveston’s situation worse than many coastal cities is that the land itself is dropping. A study published in Scientific Reports found that land subsidence, primarily caused by decades of groundwater pumping in the Houston-Galveston region, accounted for as much as 85% of the 0.7 meters of relative sea level rise recorded since 1909. When the ocean rises and the ground sinks simultaneously, the water gains on you from both directions.
The good news is that subsidence’s share of the problem is expected to shrink. Over the coming decades, its contribution to relative sea level rise is projected to decline from about 30% to 10%, partly because of regulations that have curtailed groundwater extraction in the region. The bad news is that ocean rise driven by global warming is picking up speed, more than offsetting that improvement. An additional 1.9 meters (about 6.2 feet) of relative sea level rise is projected by 2100 when both factors are combined. That figure is considerably higher than the NASA projections for ocean rise alone, because it includes the compounding effect of the land continuing to settle.
What the Seawall Can and Can’t Do
Galveston’s famous Seawall, built after the catastrophic 1900 hurricane, currently stands at an elevation of 17 feet. That sounds like a lot of protection, but the 100-year storm surge (the level that has a 1% chance of occurring in any given year) already reaches 16.5 feet under present sea level conditions. That leaves a margin of just 6 inches before water starts pouring over the top during a major hurricane.
With even modest sea level rise, that margin disappears entirely. A half-foot of rise, expected by roughly 2050, would bring the 100-year surge level right to the seawall’s crest. A foot or more of rise makes significant overtopping a near-certainty during any serious storm. Texas A&M researchers have described the current seawall as “quite vulnerable to substantial overtopping” even for its designed 100-year standard.
Plans exist to raise the seawall to 21 feet as part of a larger coastal protection project, but the timeline remains uncertain. Some planning documents describe the seawall raise as a future adaptation rather than an immediate construction priority, and no firm start date has been set for that work.
The Ike Dike and Long-Term Protection
The largest infrastructure response is the Coastal Texas Project, commonly known as the Ike Dike, a massive barrier system designed to shield Galveston Bay and the surrounding coast from hurricane storm surge. The project includes a gate system across the mouth of the bay and a double-dune barrier along the shoreline. Galveston County estimates the project will take at least 15 years to complete from the start of construction.
Even if the Ike Dike is built on schedule, it addresses storm surge, not the chronic daily flooding that comes with rising baseline sea levels. As the ocean creeps higher, low-lying parts of Galveston will flood more often during routine high tides and minor weather events, not just hurricanes. That kind of “sunny day” flooding is what gradually makes neighborhoods unlivable, corrodes infrastructure, and drives insurance costs beyond what most residents can afford.
What “Underwater” Really Looks Like
Cities rarely go underwater all at once. What happens instead is a slow squeeze. Streets flood during king tides. Storm drainage systems back up because they can’t push water out against a higher ocean. Saltwater intrudes into freshwater systems. Insurance premiums climb. Property values in the most exposed areas decline. Residents leave in waves, not all at once.
Galveston’s most vulnerable areas, the low-lying neighborhoods on the bay side of the island that sit outside the seawall’s protection, will feel these effects first. With 2 to 6 feet of combined relative sea level rise projected by 2100 (depending on the scenario and whether land subsidence is factored in), large portions of the island face regular inundation well before the end of the century. The island won’t vanish from the map on a specific date, but for practical purposes, parts of Galveston could become uninhabitable decades before the water permanently covers them.