As a kid I was fascinated by the idea of California falling into the ocean. So notorious is this concept that it was recently featured on ABC’s Scandal. The president, annoyed and questioning why he’d been interrupted, sniped “Why, did California fall into the ocean?” Tectonically speaking, that’s not possible. As an adult, I know that now.
So while looking west for excitement in the form of the ultimate Californication, back east my home state is actually teetering on the edge of aquatic catastrophe. Perhaps not as dramatic as a big chunk of California dropping into the abyss, but there are good indications parts of the Sunshine State may soon simply be consumed in salt water.
Deborah Harry prophetically crooned “The tide is high but I’m holdin’ on.” In Florida it seems the tide is high and getting higher. Tide gauges and satellites are specifically telling us sea level is rising and doing so at a faster and faster rate.
A worldwide network of 1,700 tide gauges have been monitoring the rising waters, some for more than 100 hundred years. And according to the National Oceanographic and Atmospheric Administration’s (NOAA) Laboratory for Satellite Altimetry “Current satellite observations show sea level rising at close to 3 millimeters per year, nearly twice as fast as the measured rate over the past 100 years.” NOAA states “One of the most significant potential impacts of climate change is sea level rise.”
So, is the climate changing? Has it ever changed?
By observing the earth today and applying fundamental principles of geology, we can know what happened in the past. Not just the earth’s geologic past, but past climates as well. That’s paleoclimatology. And paleoclimatology tells us the earth’s climate has changed many times in the past and predicts it will continue to change into the future.
Science has constructed a reliable history of global average temperatures over the last 500 million years. Data from the last 800,000 years is highly precise and gives us an excellent snapshot of the earth’s recent climate history. It’s a picture of a see-saw pattern of global glacial and interglacial periods when average temperatures swung back and forth radically from warm to cold.
In times of global ice coverage, water is locked up in the glaciers and relative to present day, sea levels are low. When the global climate is warm, less water is sequestered in the ice and sea levels are high.
The last major ice-age known as the Wisconsin Glaciation ended less than 12,000 years ago, marking the end of the Pleistocene epoch. We now live in the Holocene, an epoch of warm temperatures following the Wisconsin and a time when sea levels have been rising.
Temperatures climbed quickly at the start of the Holocene, leveling off about 8,000 years ago at a temperate global average of about 59 degrees Fahrenheit. Since then there have been a few temperature ups and downs, and around the end of the 19th century we began to see another increase that continues today.
NASA confirmed that February was the warmest month ever measured globally at 1.35 degrees Celsius above the long-term average.
As global temperatures increase, sea level rises due to the melting of glaciers and the thermal expansion of upper layers of the ocean.
“Sea Levels have risen as much as 8 inches in Florida in the last 100 years,” said Nicole Hernandez Hammer, Southeast advocacy coordinator for the Union of Concerned Scientists. “Sea levels around Florida are going up.”
Serious flooding was evident last year during the King Tides; South Florida’s highest tides of the year, when streets all around the region were flooded by inland waterways. “The water was so deep in some areas that kids could not get on their school buses,” said Hammer. “We are extremely vulnerable to the impacts of rising sea levels in Florida.”
Colin Polsky, director of the Center for Environmental Studies at Florida Atlantic University confirmed this in the Miami Herald. “The King Tides have gotten higher in recent years, and the King Tides we’re seeing more recently have been higher than they were predicted to be.”
Inundation is not the only issue. Rising sea level results in saltwater intrusion and that’s not so easy to see.
Duane DeFreese, Ph.D., executive director of the Indian River Lagoon (IRL) Council says he has been tracking sea levels in Florida for 15 years. DeFreese directs the IRL National Estuary Program and sees Florida’s porous limestone base as an added concern as sea levels rise.
Because the porosity (the pore space within rock) and the permeability (the ability of fluids to move through rock) of Florida’s limestone base is so high, the salt water table below coastal regions can easily intrude into our fresh water aquifers.
Fresh groundwater (the water we use for drinking and irrigation) is less dense than salt water and floats on top of salty groundwater. As sea levels go up, the depth of the freshwater-saltwater interface underground, rises as well. As the depth of that interface becomes shallower, salt water can intrude into fresh water wells and the supply of drinking and irrigation water is cut off.
“We have a very high vulnerability to even modest sea level rise,” said DeFreese. “If you look at the last century’s 6 to 7 plus inches of measured rise and project at that rate, we can clearly see that sea level rise will be an infrastructure risk issue, an insurance risk issue, an environmental risk issue and a policy issue for Florida.”
Moreover, the rise of the freshwater-saltwater interface forces the fresh water table up. Now there are long-term problems such as poor drainage, more frequent flooding and the failure of subterranean systems such as basements and septic fields. In Florida, the one, two punch of inundation and saltwater intrusion also will lead to a greater threat from storm surge delivered by tropical storms and hurricanes.
According to Hammer, 70 percent of Americans surveyed recently are concerned about rising sea levels.
For better or worse, there is a fixed amount of water on earth. If the earth’s temperature continues going up then ice melt and thermal expansion will continue to force sea levels to rise. Infrastructure adjustments and planning can mitigate the impact of rising waters, but real prevention circles back to the question of climate change. Be it naturally induced as over all of geologic time, or anthropogenic forced, the current observable climate change in the form of global warming will mean rising waters.
So if the global ocean is moving toward our wells and door steps, is there anything we can really do? Mitigation not prevention seems to be the key. We probably can’t prevent the current trajectory of rising waters, but we can lessen the impact with planning.
Cities like New York and Miami Beach have started looking away from their state capitals and to themselves for solutions. Even hyper-local municipalities such as Satellite Beach, Fla., are looking to science to help make smart decisions and provide a locally delivered response to a globally generated problem.
We will continue to watch sea level and the potential impact on Florida from its rise and fall. In our next article, we examine another staggering number, 500 million. That is the estimated cost of mitigation for the city of Miami Beach.