Flooding is common in many areas across Miami-Dade and Broward Counties after heavy rains, such as when Tropical Storm Andrea hit the Florida coast on June 7, 2013. This flooding is near Miami International Airport. Photo: National Weather Service

The National Oceanic and Atmospheric Administration report, "Global Sea Level Rise Scenarios for the United States National Climate Assessment," states that scientists have greater than 90% confidence that global mean sea level will rise between 8 inches and 6.6 feet by 2100.

In "Goodbye, Miami" (July 4th Rolling Stone), Jeff Goodell, author of How to Cool the Planet: Geoengineering and the Audacious Quest to Fix Earth's Climate, predicts: "By century's end, rising sea levels will turn the nation's urban fantasyland into an American Atlantis. "?(R)? The rising waters will destroy Miami slowly, by seeping into wiring, roads, building foundations and drinking-water supplies – and quickly, by increasing the destructive power of hurricanes. "?(R)? With just three feet of sea-level rise, more than a third of southern Florida will vanish; at six feet, more than half will be gone." Note: Three quarters of the 5.5-million South Floridians live along the coast.

Jayantha Obeysekera, director of the Hydrologic & Environmental Systems Modeling Department at the South Florida Water Management District (SFWD), notes that with each heavy rain, a frequent occurrence, inland Florida floods, there's nowhere for the water to go. Cities on the western edge of Miami-Dade County, i.e., in land, such as Hialeah and Sweetwater, are already at risk for massive flooding with every big storm. As a stopgap, SFWD over the next two decades will install 40 pumps in Miami Beach. These $70-million each pumps, can take stormwater runoff and pump it to the ocean.

Meanwhile, Biscayne Bay Waterkeeper, a clean-water advocacy group, is challenging Miami-Dade's $1.5 billion plan to repair the county's spill-prone sewage system, asserting if would make more sense to move the plants to more protected inland sites and further away from the effects of rising seas.

Yet another concern of rising tides is South Florida's fresh water supply. As the Miami-Dade "Climate Change Action Plan" points out, Florida was under water in the geologic past, which is how the state's sedimentary limestone bedrock formed (deposits of calcium carbonate from ocean organisms and algae). This geology, think Swiss cheese, is extremely porous, allowing water to flow freely throughout. This porosity connects the region's only fresh drinking water (Biscayne Aquifer) to the ocean. Increases in sea level "may push the salt-front line further inland and closer to drinking water wells, threatening the region's fresh water supply," warns the action plan.