Florida’s Water Reckoning and the Rising Cost of Climate Change
January 31, 2025
The aftermath of Hurricane Helene in Keaton Beach, Florida. September 27, 2024. Photo courtesy of The National Guard. Deed - Attribution 4.0 International.
When someone hears “Florida,” the ocean and beaches are often the first image that comes to mind. Florida’s ocean connection generated $39.9 billion in gross domestic product (GDP) in 2021 and paid $20.6 billion in wages, with tourism and recreation being the largest marine employer and source of GDP.[1] In fact, Florida employs more people in marine endeavors than any other state. This is not surprising as the ocean created all the land that we call Florida today. However, it is also the ocean that is generating Florida’s greatest climate impacts.
With about two-thirds of the state border being coastline[2] and being arguably the lowest elevation state (depends on the metric used relative to Delaware)[3], sea-level rise is a major issue for Florida.
Global mean sea level began to rise above natural variability in the 1860s[4] and the rate of rise is the fastest in the last 4,000 to 5,000 years[5] or since the last ice-age ice sheets disappeared[6]. By the 2020s, global mean sea level had risen 8 to 9 inches.[7] The rate of global mean sea-level rise is also increasing and has more than doubled from the early 1990s when it was about 0.8 inches per decade to the early 2020s when it was 1.8 inches per decade.[8]
Now that is global mean sea-level rise and how that is expressed at coastlines varies widely throughout the world. Ocean currents unevenly redistribute water while changes in ice sheets impact the gravitational pull of these ice sheets on ocean water, warping its surface. Then coastlines themselves are moving due to ongoing adjustments from the last ice age that makes coastlines rise (e.g., northern coastal Maine) and fall (e.g., Virginia), in response to sediment loading that makes the coastlines sink (e.g., Louisiana), and because of tectonic uplift that raises coastlines (e.g., southern Alaska).[9]
In Florida, local sea level has risen 6.1 inches to 8.9 inches since 1970, with the largest rise occurring in Miami-Dade County.[10]
The city of Miami has the highest number of residents and properties exposed to flooding at high tide along the Atlantic coast[11]. Miami-Dade County underwent the greatest increase in population living within 3.3 feet (1 meter) of sea level[12]. Tidal flooding delays have increased Floridian average commute time by 360% between 2003 and 2016, the largest increase anywhere in the country.[13] At extreme tidal levels, the city of Miami is virtually already underwater.[14]
Now, combine these issues with the fact that Miami’s large buildings are themselves causing the land to sink due to their weight[15] and the issue of sea-level rise is a clear and present danger to Miami today, not some distant issue.
Downtown Miami tidal flooding in October 2016.
In addition to the rising sea level, the ocean is also damaging Florida via hurricanes. The number of North Atlantic hurricanes and the season length have increased as the ocean and the globe warmed.[16]. At the same time, the amount of rain falling in Florida during a given hurricane also increased.[17] Unlike sea-level rise that emerged from natural variability around the same time that humanity began to adopt fossil fuels at a large scale in the late 1800s, hurricanes have always occurred, making their attribution to greenhouse gas emissions more difficult to detect.
That said, hurricane formation is now clearly linked to Atlantic sea surface temperatures, which have been warming along with the rest of the globe as we continue to burn fossil fuels and emit other greenhouse gases.[18]
For instance, the 2020 extremely high Atlantic hurricane season was made twice as likely by human greenhouse gas emissions[19] with rainfall rates and accumulated rainfall increased by 11% and 8%, respectively[20]. In the case of Hurricane Ian which hit Florida in 2020, its rainfall amount was increased by 18% from human-caused climate change.[21] Ocean heat also increases the strength of hurricanes. Focusing on recent hurricanes that impacted Florida, human-caused climate change increased Idalia from a category 2 to 3 storm and Ian from a category 4 to 5, while the strength of Elsa and Eta also increased but within their categories 1 and 4, respectively.[22]
These hurricanes kill people and cost tens of billions of dollars.[23] In the last 5 years, nine hurricanes hit Florida, causing a cumulative $244.5 billion in damages and directly killing 450 people.
That’s an average of $50 billion dollars of damage a year, which, circling back to the GDP and salary numbers at the beginning of this article, completely offsets the ocean’s financial gains to Florida. This five-year period from 2020 through 2024 is unprecedented in the 44-year NOAA record of billion-dollar disasters. The next closest five-year period is from 2001 to 2005 when five hurricanes hit Florida, causing $89.3 billion in damages and directly killing 161 people. That is, in the first five years of the 2020s versus 2001-2005, Florida had nearly double the number of landfalling hurricanes, 2.7 times the cost in damages, and 2.8 times more deaths. Conversely, no hurricanes that caused at least a billion dollars in damage (yes, this is adjusted for inflation) hit Florida in the 1980s.
Hurricane Milton seen from ISS on October 8, 2024.
Now, these are deaths caused directly by hurricanes and recent research has identified significantly larger, lingering impacts of hurricanes on mortality. Looking at all hurricanes that hit the United States from 1930 through 2015, each hurricane causes over the following 15 years an average of 7,000 to 11,000 excess deaths relative to the average 24 immediate deaths from the storm.[24] Not surprisingly, Florida is the locus of these excess deaths where 13% of deaths in Florida between 1930 and 2015 can be traced to the impacts of hurricanes.[25] Such numbers may seem shocking but should not be surprising when one considers the impact of hurricanes on infrastructure. In the Miami metropolitan area, 78% of the hospitals, 71% of hospital beds, and 72% of roads within a mile of the hospital are at risk of flooding during a category 2 hurricane; the rise in sea level projected by the end of this century increases these numbers to 84% of hospitals and their beds at risk of flooding.[26]
I know this is a tragic summary of how the ocean, in response to greenhouse gas emissions, is essentially taking Florida back to its watery origins millions of years ago. However, if we end our use of fossil fuels, the Earth will begin to suck up all the carbon dioxide we’ve emitted since the industrial revolution[27], reducing its heat-trapping effect and causing global cooling within decades of putting that final nail in fossil fuels’ coffin[28]. It is that simple. End fossil fuels and the world will begin to improve. But until we bury fossil fuels in a very deep hole and joyously tap dance on their grave, it will only get worse.