Florida, a low-lying peninsula with extensive coastlines, frequently faces public concern regarding its vulnerability to rising sea levels. This article explores the science behind global sea level rise, Florida’s unique geological susceptibilities, current observations, future projections, and clarifies what “underwater” truly signifies in this context.
Global Sea Level Rise Drivers
Global sea level rise stems from two mechanisms: the thermal expansion of ocean water and the melting of land-based ice. As the Earth’s atmosphere warms, oceans absorb heat, causing water to expand in volume. This thermal expansion directly contributes to sea level rise and accounts for approximately half of the observed global sea level rise.
The second major contributor is the melting of land-based glaciers and ice sheets, including those in Greenland and Antarctica. When this ice melts, the water flows into oceans, adding to their overall volume. Their melting rates have been accelerating, significantly contributing to the observed sea level increase.
Florida’s Geological Predicament
Florida’s unique geology makes it susceptible to rising sea levels. Its exceptionally low elevation and flat topography mean small increases in sea level can inundate vast areas. Much of Florida’s land sits only a few feet above current sea level, offering little natural defense.
A significant factor is its porous limestone bedrock, often referred to as karst topography. This permeable rock allows saltwater to easily penetrate inland through underground channels and fissures. Saltwater intrusion can affect freshwater aquifers and ecosystems far from the visible coastline, even before the land surface is permanently submerged. The absence of solid rock barriers also complicates flood defense construction, as water can simply seep underneath or around them.
Observed Changes and Predictive Models
Current observations indicate that sea levels are already rising along Florida’s coasts, with data from tide gauges showing an accelerating rate. Areas like Miami and Key West have recorded consistent increases in mean sea level over recent decades. This observed rise is not uniform, but leads to more frequent high-tide flooding, often called “sunny day flooding.”
Future projections for sea level rise in Florida depend on scientific models that consider different greenhouse gas emission scenarios. Under moderate emissions, models suggest a global mean sea level rise of about 1 to 2 feet by 2050, potentially increasing to 2 to 6 feet by 2100. Higher emission scenarios could lead to even greater increases. These projections imply that coastal areas will face more extensive and frequent inundation, impacting infrastructure, freshwater supplies, and ecosystems.
The gradual nature of sea level rise means that “underwater” is not a sudden, singular event but a progressive process. Different parts of Florida will be affected at varying rates due to localized elevations and geological characteristics. While long-term projections carry inherent uncertainties, the scientific consensus indicates a continuing and accelerating trend of sea level rise.
Defining Submergence
The concept of “Florida being underwater” is often misunderstood as a sudden, catastrophic event. In reality, it is a gradual process characterized by increasing inundation and chronic flooding. Coastal areas will experience more frequent “sunny day flooding,” where tides alone cause water to cover streets and low-lying properties.
Over time, this persistent flooding can transform into permanent inundation, leading to the slow loss of land. Rising sea levels also intensify the impact of storm surges, allowing coastal storms to push water much farther inland than before. Saltwater intrusion, facilitated by Florida’s porous limestone, will continue to contaminate freshwater sources and alter coastal ecosystems, even in areas not yet visibly submerged. The effects will vary across the state, with lower elevation areas experiencing impacts sooner and more severely.