Climate Change in Florida – Threat from Below

In the U.S., we’ve seen year after year of record high temperatures, droughts in Texas, massive storms and surges, shifting plant zones and loss of species diversity. As the state with the most shoreline at risk, the climate change threats to Florida from sea level rise are legion. Many of our “leaders” continue to deny that the threat is real, the threat is global, and it will impact all of us.Studies have documented risks to shorelines, coastal mangrove migration at the expense of tidal freshwater forests, impacts on economically important species like oysters and finfish, and flood insurance rate hikes. Increasing tidal flooding and decreasing relative elevation are strongly correlated with a decline in forest species richness. As mean high tides lines rise, many of our coastal communities face water inundation and ultimately, property abandonment. In spite of these risks, many communities fail to restrict building in high risk areas, ignoring the future costs of these losses. In Miami, the cost of that ignorance is right here, right now. Saltwater flooding the streets in Miami Beach.Photo courtesy of Jon Ullman. The coastal zone along the Big Bend of Florida supports an established and highly productive area of oyster reefs with great economic and ecological importance. A study of the Big Bend from Crystal River to Apalachee Bay using aerial photographs of the coastal zone from 1982 to 2010 assessed the health and size of oyster reefs in four key areas. Results indicate a significant decline in the size of all the reefs investigated, with offshore reefs losing the greatest area (88%), followed by nearshore reefs (61% decline) and inshore reefs (50% decline). The low-density development of the area and harvest regulations enacted in 1987 reduces the likelihood that direct human damage is the major cause for the observed decline. The study hypothesizes that sea-level rise (tide gauges documented a 5 cm rise in the study area over the 28-year period) may have increased salinity, especially on the offshore reefs, encouraging more predation and possibly increasing sedimentation and wave energy, leading to the decline of the oyster reefs.Perhaps the most menacing and least studied threat is the threat below. Florida’s base is a porous rock called karst – limestone that is honeycombed with openings through which water flows. It gives us our springs and rivers, but also provides sink holes and the opportunity for salt water intrusion from the coastal zone. The problem is increased by over-pumping our freshwater, a water table near the surface, and restricting or redirecting natural, historic water flows. Beneath us, salt water moves in when fresh water supplies move out. Yet, our search for peer-reviewed studies regarding karstic saltwater intrusion related to sea level rise produced no results.Some cities and counties have responded with a community stakeholder approach, including Miami-Dade’s Climate Advisory Task Force and tiny Satellite Beach on the Atlantic coast. In 2010, the Florida Oceans and Coastal Council completed a comprehensive study called: “Climate Change and Sea-Level Rise in Florida – an Update of the Effects of Climate Change on Florida’s Ocean & Coastal Resources,” and it’s worth a read for all city and county planners, and for all of us who care about the future of Florida and of our communities.So much of this damage happened in the past and continues today. But the real issue is the future and those who will inherit it. For me, it’s my 10-year old grandson. When I asked him what he thought about climate change he said “it will get extremely hot. I have asthma and it’s harder to breathe when it’s hot …We have to find a new energy source. Not one that, in order to find it or make it, we have to pollute. We could use solar energy to cool our houses. When the Sun’s not out we store it up somewhere and use that on the cloudy days.” Out of the mouths of babes…Cathy Harrelson is GRN’s Florida Organizer.

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