Climate Change and the Everglades: A Case Study
By Makenna Christensen
Photo by Asael Pena
It is time to acknowledge all things ocean! As we neared the end of the recent 2020 World Oceans Week (June 8-14), all of us at Future Frogmen felt it was an important time to dive into a local conversation of water security and how access to clean water is a global health and economic issue. While this piece highlights the necessity of clean water, it is also meant to shed light on the unforeseen consequences that come along with losing coastal freshwater resources. It is natural to raise an eyebrow and ask, what does access to freshwater and drinking water have to do with the ocean?
The answer begins with sea-level rise. As our glaciers and ice sheets continue to shrink in size, the amount of meltwater flowing from these masses into the ocean increases exponentially. Sea-level rise contributes to wetland and coastal habitat loss, urban land encroachment, and the destruction of freshwater aquifers.
While there are natural periods of regression in glaciers, since the beginning of the twentieth century we have seen a continual increase in the temperature of the upper ocean causing an increase in ice loss. This is due to the warming of the earth through the trapping of greenhouse gases. The upper ocean is understood to be the layer between deeper ocean and the surface, which is subject to fluctuations in the atmosphere. According to NASA, the ocean absorbs up to 90 % of trapped heat; however, as we continue to degrade our environment, the amount of heat caught in the atmosphere will only increase, which will begin to perpetuate a negative feedback loop. Sea-level rise is directly affected by the phenomena highlighted above. The thermal expansion of water occurs when water molecules begin to heat up and that increase in temperature forces molecules to move more rapidly which causes the volume of the water to expand. Thermal expansion occurs naturally in a system, yet, it is exacerbated by increasing global temperatures.
Let’s take a closer look at a case study from the Florida Everglades and coastal cities where the impacts of sea-level rise can already be seen, as streets now often flood during storm surges and high tides. Not only do the Everglades provide significant protection inland against storms, the coastal wetlands also support a biodiverse habitat meant to provide recreational and ecosystem services for the city, according to Florida International University.
Access to clean water is only half the battle for Floridians who reside in the Everglades and coastal regions. According to the National Oceanic and Atmospheric Administration (NOAA), in the United States, close to 40% of the population lives in high population-density areas along the coast. The negative implication is that large populations will eventually be forced to inland cities, putting additional pressure on already-slim resources and land usage.
Photo by Wade Austin Ellis
While average projections vary, the NOAA states that even if greenhouse gas emissions are curbed, we will see at least a one-foot rise in sea levels globally by the end of the century. However, if we continue to rely on nonrenewable energy sources, such as fossil fuels and nuclear power, projections begin to reflect a much darker future. For example, a Florida Atlantic University study estimates that by 2050 we will witness storm surge flooding reaching more than five feet above high tide. This means the displacement of over six million US residents who live on land less than five feet above high tide.
If sea-level rise continues and the ocean reclaims more coastal land, the residents of South Florida will be pushed from their homes. Similarly, saltwater will not only further encroach upon Florida’s coastal residential areas, but also on their local aquifers, such as the Biscayne Aquifer, which provides drinking water for three million people in South Florida.
Aquifers are deep underground layers of porous rock such as limestone that allows freshwater to permeate through the rock and reside in a pool underneath known as groundwater. Saltwater intrusion into freshwater aquifers results in a brackish mix of unusable and contaminated drinking water. Saltwater works to erode and eventually collapse the peat soil barriers that protect the Everglades aquifers. If this occurs, we will also see increased elevation loss resulting in further flooding throughout the coastal regions.
The Everglades Foundation: Saltwater Intrusion
The agricultural economy of Florida drove initial changes to waterways in 1948 when Congress authorized the “Central and Southern Florida Project for Flood Control and Other Purposes.” By reducing the amount of water that flows outwards to the ocean, salt and brackish water may intrude into previously freshwater areas. Similarly, in reducing the amount of freshwater that moves south towards the coast has begun to destroy many Everglades habitats. For example, wading bird populations have shrunk 90% over the last century.
Photo by Alex Shutin
As waterways are channeled inland for domestic resources and as sea levels continue to rise, we are putting the biodiversity of the Everglades, a place that is home to 67 endangered species, and over 300 bird species, at risk. Diverting water away from the coast for inland agricultural and domestic use means there is less water to replenish the Biscayne Aquifer year after year. Therefore, it is not only our well-being we have to think about but the survival of an entire ecosystem.
Using peat barrier reconstruction, some scientists have begun to develop mitigation efforts to restore the wetlands and Everglades. Repair of the peat barrier between freshwater marshes and coastal saltwater is an attempt to rebuild eroded areas and lost plant life due to saltwater intrusion. Another mitigation tactic would be to get rid of the canals that redirect water away from the coast, allowing the aquifer to fill up naturally over time.
National water insecurity seems far-fetched for a country like the United States; however, if we remain on the current path of material consumption and environmental exploitation water scarcity will become an even bigger reality. Ocean encroachment is not just occurring in Florida, but in coastal regions globally. With the continued loss of wetland habitats combined with droughts and water restrictions already seen across the US, access to coastal freshwater will be hampered, hence rendering populations unable to survive.
If saltwater continues to infiltrate the Everglades, its freshwater ecosystems will be at risk of collapse and our residential areas and services will be lost. For those at home who are asking how they can play a part in reducing sea-level rise, the possibilities are endless. However, mitigation always begins with individual lifestyle changes. From simple changes like reducing your energy use and greenhouse gas emissions, to getting involved in protecting your coastal wetlands, we can help to preserve local watersheds while also scaling back our environmental footprint one consumer at a time.
Sources:
https://www.climate.gov/news-features/understanding-climate/climate-change-global-sea-level
https://sealevel.climatecentral.org/news/floria-and-the-rising-sea
https://sealevel.nasa.gov/ understanding-sea-level/global-sea-level/thermal-expansion
https://www.jpl.nasa.gov/edu/news/2015/9/3/teaching-the-science-of-earths-rising-seas/
http://wetland.fiu.edu/coastal-peat-marsh
https://www.sciencenews.org/article/florida-everglades-freshwater-saltwater-sea-level-rise