Climate Change Threatens Florida's Drinking Water
Much of the damage to Florida's water supply will take place out of sight, in the underground aquifers that provide most of the state's drinking water. As rising seas nibble at the state's coastline, saltwater intrusion will also creep steadily inland.
"We used to assume that we could use the past records to predict the future," said Mark Stewart, a professor at the University of South Florida. "Now, we just don't know."
To cope with uncertain freshwater supplies, the state has turned to expensive reservoirs and energy-intensive desalination plants, and plans to build even more. Florida could turn to schemes that seem unthinkable today, like pumping wastewater into aquifers that supply our drinking water.
"Recently, there has been rising agreement among water managers that this is an issue that needs to be addressed," said Chris Milly, a research hydrologist with the U.S. Geological Survey. "Climate change is real, and affects the water system enough that it will have an impact on the decisions they make on how they deliver water to their customers."
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Florida's climate has already begun to change. Sea levels have started to rise. Saltwater fish are swimming farther upstream, while saltwater mangroves invade freshwater marshes. Rainfall has become less predictable. Rivers and reservoirs are at near-historic lows.
Climate models offer little guidance, Stewart said. Some predict more rainfall, others predict the state will devolve into a desert. Despite the uncertainty, there are worrying challenges ahead, he explained.
"It's like the federal deficit," Stewart said. "The good news is it will happen really slowly, over decades. The bad news is our kids will pay for it."
The International Panel on Climate Change predicts that as the climate warms, oceans will expand, pushing sea levels up by nine to 23 inches by the end of the century. The estimate doesn't include glacial melting. Some scientists predict that seas will rise three to five feet in that time. At little more than three feet, the sea will cover Florida Keys and the Everglades, and soak coastal parts of cities like Tampa and St. Petersburg, according to a recent report by Florida Atlantic University.
The damage underground could move faster and cause more devastation. Saltwater intrusion could extend 50 percent farther inland than the above-ground impact, said Motomu Ibaraki, an associate professor of earth sciences at Ohio State University and author of a recent study on how rising sea levels could damage underground aquifers. A state like Florida, which heavily pumps its groundwater, could see even faster intrusion, he said. As sea levels rise and saltwater moves inland, underground freshwater supplies will become brackish and undrinkable.
The scientific uncertainty often gets subsumed into the political battle between those who believe climate change is a natural cycle and those who believe that it's man-made. With a lack of clear answers about what direction climate change will take, it's hard to muster the political will to curb greenhouse gas emissions by dramatically altering the way we consume energy, Stewart said.
"The public has a hard time dealing with scientific uncertainty," Stewart said. "They want a yes or a no."