Effects of Sea-Level Rise on Florida

GLY 1073 Term Paper

By:  Adam Harpool

 

 

 

Introduction

 

Though of all of the states of the USA and all American citizens are likely to experience some of the effects of global warming over the next 100 years, in few places are the potential negative consequences likely to be as great as in the Sunshine State.  As identified by a stunning graphic in Al Gore’s An Inconvenient Truth, Florida faces nothing short of a disaster of fairy-tale proportions without actions being taken to mitigate the steadily advancing trend of increasing global warming due to anthropogenic combustion of greenhouse gases.  In this paper, I will briefly analyze the causes behind sea level rise, the evidence for past and future sea level rise, and then thoroughly discuss how predicted sea level changes will adversely affect Florida.  The paper will close with some possible solutions to this escalating problem and a brief summary of my findings.

 

The Causes of Sea Level Rise

 

For many, sea level rise is a phenomenon that is easy to visualize but not necessarily easy to comprehend.  Perhaps one of the best analogies regarding sea level rise treats the Earth’s oceans as water in a cup, with some ice cubes to represent the gigantic icebergs and other ice formations that float about freely.  Some critics of global warming contend that sea level rise will not be a serious problem at all because the melting of the “ice in the cup” due to warmer water temperatures – to extend the analogy, the melting of icebergs and ice formations – will not cause the cup to run over, or raise sea levels.  They are right in their analysis in that regard, but in dealing with sea level rise we are principally concerned with the ice that is not already in the ocean; this is principally the ice contained in the Arctic (Greenland, Artic ice caps) and the Antarctic (Antarctica.)  To complete our cup analogy, simply imagine adding extra ice cubes to a cup that is already at its rim, and you quickly can create a nasty mess.  For our world, the ice on Greenland and Antarctica could very well prove to be the extra ice cubes needed to significantly raise the oceans.  Scientific observations seem to confirm that humans are indeed altering the nature of these two bodies in manners not seen in recent geologic history.  For example, observe the figure below:

 

Figure 1:  Extent of annual melting on Greenland
 
 

 

Figure 1 shows the extent of the area of Greenland that melts each year before refreezing in the winter.  Over the short period of one decade between 1992 and 2002, this area has more than tripled in size; an analysis in 2005 showed that the area of melting had increased even more.  As general circulation models utilized by myriads of leading scientists nearly universally agree that the polar regions of the Earth will be the most heavily impacted by global warming, this change seems heavily correlated to increasing temperatures.  The results are easy to understand:  more water in the ocean each year means higher sea levels.  And as the next two figures indicate, this is no longer purely theoretical.

 

Figure 2:  Flooding on Tuvalu due to sea level rise
 

Figure 3:  Location of Tuvalu islands
 
 

 

 


The flooding on the small Pacific archipelago of Tuvalu that has caused dozens of local residents to have to evacuate demonstrates the vulnerability of low laying coastal regions to the smallest increases in sea levels.  Westerners, however, are much more likely to pay attention to what is happening in their own back yards – could something of this magnitude really happen in the United States?

 

Scenarios for sea level rise

 

Figure 4:  Sea level trends, last century near US coast
 

 

It is universally agreed upon by respected scientists that sea levels have risen in the last century worldwide by about ten-twenty centimeters, or six-eight inches.  Figure 4 shows the rise in sea levels along the US coast during the Twentieth and early Twenty-First centuries, roughly mirroring the global trends (with the notable exception of some parts of Alaska, where due to the rising of land it appears that sea levels have actually been receding.) Currently, sea levels are rising at a rate of approximately two to three millimeters per year along the US Atlantic Coast, somewhat faster than along the US Pacific Coast.  Even continuing at that current rate (2 – 3 mm per year) changes could be rather significant, but there are in fact a wide possibility of future scenarios for sea level change.

 

 

Figure 5:  Range of projections for future sea level rise
 
 

 

 

 


Figure 5 summarizes the range of possible scenarios for sea level rise worldwide in the next century.  As the links between the melting of the ice in Arctic and Antarctic regions and anthropogenic emissions of greenhouse gases has been established, we can deduct that the curves on the above graph are nearly directly related to how we control our emission of greenhouse gases into the future.  Accordingly, we can clearly ascertain “best case” and “worst case” quantitative scenarios from the graph; a best case scenario, which would come about due to a rapid reduction in greenhouse gas emissions, would entail a sea level rise of only .09 meters globally, whereas the worst case scenario, essentially a “business as usual” path in which humans do little or nothing to alter current trends in fossil fuel combustion, would bring about a sea level rise of .88 meters to 1 meter globally.  The fact that the curve actually observed in this wide range of scenarios is largely contingent upon human activities demonstrates clearly the power that humankind has over the future of our civilization here on Earth.  Unfortunately, and regardless of our future actions, due to the current greenhouse gas emissions sea levels are now rising fifty percent faster than they have in the past century, and that acceleration will be difficult to curtail.

 

Florida’s Vulnerability

 

With around 1,350 statute miles of coastline along the Atlantic and Gulf Coasts combined, it is clear that changes in sea level will inevitably affect Florida in various ways.  Our vulnerability is compounded by our extremely low mean state elevation of one hundred feet, second only to Delaware’s of sixty feet.  A multitude of areas in Florida are situated exactly at sea level.

 

Figure 6:  Coastal elevations, Central and Southern Florida
 

 

 

Figure 6 shows the areas in Central and Southern Florida that lay at the lowest elevations in the state, all of them ten meters or less above sea level.  In general, the inland areas of Florida and areas in the northern parts of the state are situated at significantly higher elevations than coastal areas and southern regions of the state; thus, these northern and inland areas are much less susceptible to rises in sea level.  But for the areas in blue on the graphic above, even the minutest changes in sea level could have drastic impacts in the near future.

 

Scenarios for Florida’s Future

 

Using complex computer systems, scientists have been able to develop models that predict exactly what will happen to the coastal and inland areas of Florida based on rises in sea levels; there is a general consensus regarding these models, and they raise grave concerns for the future of our state.  Let us start with a view of Florida in its present state:

 

Figure 7:  Current sea levels in Florida
 

 

Based on widely agreed upon models, it is highly likely that sea levels in Florida could rise at least one meter in the next century; Figure 8 shows what would happen to Florida with this sea level change.  Areas in red would be completely inundated.

 

Figure 8:  1 meter rise in sea levels, Florida
 

 

As the figure clearly indicates, the devastation from such a minute change would be enormous, with virtually every square inch of land directly bordering both the Atlantic and Gulf Coats experiencing widespread flooding.  The highly vulnerable Florida Keys island chain would be entirely underwater.  Near the First Coast are of Florida surrounding Jacksonville, there would also be significant flooding in and around the Saint Johns’ River, spreading down into Central Florida near the Orlando area.  I will discuss the exact quantitative effects of these changes briefly, but before that we should analyze other changes that would be possible in sea level.

 

Figure 9:  2 meter rise in sea levels, Florida
 

 

Figure 9 shows the effects of a two meter rise in sea level on Florida; though not likely in the next century, a change of this magnitude is nearly a certainty if humans continue with current fossil fuel based emissions well into the future.  In this scenario, the entire lower tenth of the state of Florida – stretching from Collier County in the West to Miami-Dade County in the East – is underwater, and there is more significant flooding near the Orlando and Jacksonville regions, the largest cities in Central and Northern Florida, respectively.

 

 

 

Figure 10:  5 and 6 meter rise in sea levels, Florida
 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


                                                                                                                                                                    

 

The last figure simulates the effect of a much more drastic rise of five or six meters in sea levels.  Changes of this scope are not likely in the lifetimes of today’s college students – or perhaps even their children – but are included because they are essentially identical to the image of a flooded Florida included in Al Gore’s An Inconvenient Truth.  Projections of this scope are based on the melting of half of the ice in Antarctica, or all of the ice on Greenland, which would raise global sea levels by around twenty feet.  Changes of this magnitude would flood all of Southern Florida and nearly completely destroy every coastal city in Florida.  Only inland areas such as Tallahassee, Gainesville, Lakeland/Winter Haven, and Orlando would be largely spared from inundation under either of these scenarios.  Again, these changes are highly unlikely in the short-term  - the next 100-200 years – they would be quite possible assuming that men in the future continue to emit greenhouse gases at rates similar to those of today.

 

Effects on Florida:  A Quantitative Analysis

 

For those considering living in Florida, these potential changes in sea level should be taken seriously as they would radically alter all elements of life across the state.  A variety of aspects in Florida will be affected, starting most obviously with the distribution of its population.

 

Figure 11:  Florida’s “Most Vulnerable” Counties
 
 

 

 


County

Population

Miami-Dade (Miami)

2,363,300

Broward (Fort Lauderdale)

1,754,893

Palm Beach (West Palm Beach)

1,243,230

Pinellas (St. Petersburg)

929,537

Lee (Fort Myers)

514,295

Sarasota (Sarasota)

355,477

Collier (Naples)

296,678

Manatee (Bradenton)

296,385

Charlotte (Punta Gorda)

157,134

Monroe (Florida Keys)

78,284

Total Population

7,989,213

10 counties, 46% of Florida’s population

(State 2004 population: 17,397,161)

 

As in most other states, the population of Florida is distributed in a highly uneven manner.  By analyzing Figures 6 and 8 above, we can determine a list of the counties in Florida that are most likely to be heavily affected by rises in sea level; those counties are listed above in Figure 11 (exact per county elevation data was not established.)  Florida’s 67 counties totaled around 17.4 million residents as of a 2004 estimate, but our ten most vulnerable counties – all of them coastal – count for nearly 8 million people, or roughly 46 percent of our total population and a number of citizens approximately equal to the population of the state of Georgia in 2000.  The list includes some of Florida’s largest urban areas, most notably the entire South Florida metro and St. Petersburg.

 

Though all of these counties are coastal are inherently vulnerable to changes in sea level, their problems are exacerbated by the most troubling aspect of land use in Florida:  excessive coastal development, as illustrated by Figure 12.

 

Figure 12:  Population Density in Florida
 

 

In virtually every coastal county in Florida, the overwhelming majority of development is within a few miles of the coast.  Coastal development extends in a nearly contiguous string some 400 miles from Fernandina Beach in the north to Miami in the south along the Atlantic Coast, and from Tampa to Naples on the Gulf Coast.  In the sprawling and highly populated South Florida area, stretching 100 miles from Palm Beach to south of Miami, development never reaches more than twenty miles inland from the coast due to strict environmental regulations protecting the Everglades and other estuaries, and many developed areas are often only five or ten miles wide.  Population densities in some parts of highly urban South Florida exceed 10,000 people per square mile, surpassing cities such as Los Angeles.  Extremely low-laying Pinellas County, essentially a “peninsula on a peninsula” where a body of water is never more than 15 miles away is Florida’s most densely populated county overall.  In a stark contrast, large tracts of land in the inland parts of Central and Southern Florida are virtually uninhabited, and the least vulnerable northern regions of the state – most noticeably, the Panhandle and North Central Florida – have for many years been among the more sparsely populated regions of the state.  This development profile means that, paradoxically, the parts of the state most vulnerable to sea level rise are the most highly populated ones, while the least vulnerable parts of the state are the least populated.

 

Sea level rise will inevitably affect Floridians in ways never before encountered in our state’s history.  If the models hold true, millions of Floridians living along the coastlines would have to relocate, and a relocation of this magnitude would make the disastrous Hurricane Katrina catastrophe in New Orleans look minor by comparison.  This influx of new residents across all ranges of the socioeconomic ladder could potentially cripple other metropolitan areas in the United States.  Financially the outlook is just as dire.  Over the course of the last fifty years, Florida has transformed from a sparsely populated, largely agrarian state into a major population center and economic powerhouse.  Florida’s gross state product (GSP) – the sum of all goods and services produced within the state – has now reached approximately $500 billion, the 4th largest in the United States behind only California, New York, and Texas.  Florida’s booming population of nearly 18 million is also the 4th largest in the country and will almost certainly bypass New York State to become the 3rd largest by 2010.  Any significant devastation of the Florida economy will have widespread repercussions on the US economy and consequently the world economy, quickly erasing billions of dollars of investor wealth and perhaps resulting in severe recessions or depressions.  With insurance companies already suffering from enormous losses in Florida due to hurricanes, it is likely that we would witness widespread insolvency in an industry that simply would not possess the financial means necessary to cover the multi-billion – perhaps even trillion - dollar losses brought about by massive flooding.   The South Florida area alone – Florida’s most vulnerable urban corridor – counts for around one-third of the state’s economic output, and the ten most vulnerable counties account for a staggering 57 percent of the personal income in Florida.  The state generates some $110 billion per year from real estate development – the vast majority of which is coastal or only slightly inland – and tourism brings in another $60 billion per year; both of these industries would be decimated by sea level rise.  With many Florida beaches already only existing due to artificial support, Floridian taxpayers would face the prospect of having to spend an astounding $8 billion just to temporarily restore beaches that would continue to erode each year due to the increasing sea levels.  Virtually all aspects of life in the Sunshine State would be radically altered, in a negative way.

                                                                                                                                      

Damage to Florida’s Aquifers: A Short-Term Concern

 

While the issues mentioned up to this point are extremely serious and should be of the utmost concern to all Floridians, they are also undeniably long-term issues that will likely not affect us directly for decades to come.  However, there is an issue partially related to sea level rise that is already affecting a critical element of life in Florida – saltwater intrusion into Florida’s aquifers.  Some scientists and urban planners are arguing that this should be considered our most urgent short-term problem in Florida, as our lifestyle is highly dependent upon having usable freshwater available on demand.

 

Figure 13:  Florida’s Water Table Elevation
 

 

Figure 13 shows the elevation of the water table across Florida.  In geology, the water table is the surface at which the pressure of the air is equal to the pressure of water – in general, aquifers originate just under the water table, and thus wells must be at least as deep as the water table in order to reach the porous, liquid-filled rock under it (in Florida, this rock is mostly limestone.)  In many coastal regions of Florida – in the southern parts of the state in particular – the water table is often situated directly at sea level.

 

How does saline ocean water end up in the aquifers?  In Florida, we face a “triple threat” scenario: we have low water table elevations, combined with greatly increasing water usage (equating to more groundwater pumping due to rapidly increasing population and urbanization), and increasing sea levels.  As sea levels rise, water with higher levels of saline concentration can seep into the aquifer; groundwater pumping, which lowers aquifer levels, helps facilitate this process.  Aquifers all across Florida, including those in inland areas, are currently facing tremendous stress due to our incredible population growth, but coastal aquifers are of particular concern.

 

Figure 14:  Risk to Biscayne Aquifer
 
 

 

 

 


The Biscayne Aquifer – the principal aquifer in the most heavily urbanized regions of Southern Florida – is the quintessential example of a low-laying aquifer that is highly vulnerable to saltwater intrusion due to man’s activities.  Unfortunately, portions of this critical aquifer have already been irreparably damaged; in a large portion of the aquifer situated east of 15th Avenue in Hollywood, the water from the aquifer has become too salty to even be usable for lawn irrigation.  The ominous threat of more damage of this nature forced the South Florida Water Management District to take legal action to curtail the amount of groundwater pumping allowed by certain agencies, and to embark on several programs emphasizing the importance of conservation and limiting water usage.  Though it is to be expected that the lowest laying portions of the state in South Florida would be the first to be affected by this problem, Northern and Central Floridians should remain vigilant, as some degree of saltwater intrusion has been observed in the Floridan Aquifer as far north as Walton County in the extreme western Panhandle.  With Florida adding an estimated 1,000 people per day and each of these residents expecting large amounts of water for a comfortable existence, Floridians must take appropriate actions to protect our aquifers and ensure that saltwater intrusion does not devastate our largest sources of freshwater; if this is allowed to happen – as it quite possibly could in a few decades – the effects on the state could be drastic and require expensive projects to desalt the aquifers.

 

Long-Term Analysis and Mitigation

 

Assuming that men continue currently established trends in fossil fuel combustion indefinitely into the future, we could effect melting to act as an auto-catalytic (self-reinforcing) cycle; while ice, a large part of earth’s albedo, is highly effective at reflecting sunlight back into space, when the same sunlight strikes open water most of the heat energy is absorbed.  Thus, as more and more ice in the polar regions melts, the water temperature will rise at a more rapid pace, accelerating the pace at which the remaining ice melts.  Over a long-term period of several hundreds of years, this could bring about the complete melting of Greenland, Artic ice caps, and Antarctica, with the potential to raise global sea levels by well over 40 feet.  With this amount of rise in sea levels, Florida would no longer exist as we know it, as Figure 15 indicates.

 

Figure 15: Florida, 50+ feet rise in sea levels
 

 

To protect and ensure the future of the Florida of today, it is necessary that citizens of the industrialized nations of the world – particularly, those in the United States – begin to take actions to minimize, and hopefully eliminate, greenhouse gas emissions into the atmosphere.  Some suggestions to accomplish this include, but are certainly not limited to:

 

  • Minimizing coastal development in Florida; this could be accomplished by stricter zoning regulations, higher impact fees and taxes, or other means.  The overwhelming consensus of ecological/environmental advocates and urban growth managers agree that coastal development in Florida has reached unsustainable proportions and that some of the growth our state is experiencing should be funneled into inland areas.  Less coastal development will help minimize the effects of coastal flooding and hurricane damage.
  • Focusing on swamp and marsh restoration projects, most notably in the increasingly polluted Everglades.  The Everglades help funnel freshwater into the Biscayne Aquifer, and helping to restore the swamps and estuaries in our state will have a wide variety of long-term benefits.
  • Most notably, we must continue to minimize our greenhouse gas emissions; a list of steps that can be taken to minimize carbon emissions can be found here.  Florida itself has considerable progress to work towards in this regard, as we currently rank 5th among US states in terms of our greenhouse gas emissions.

 

Conclusion and Summary

 

The actions that we collectively take in the next century will have a tremendous impact on the state of Florida.  In particular, we should remember that:

 

  • Without actions to alter our current carbon-based energy systems, sea levels are likely to rise by one meter in the next 100 to 150 years.
  • In Florida, a sea level rise of just one meter will permanently displace millions of residents and cause many billions – perhaps trillions – of dollars in damage, causing widespread damage to the US and global economy.  Sea level rises higher than this would simply exacerbate the problems.
  • In the short term, Floridians must focus on preventing damage to our aquifers through saltwater intrusion; sea level rise (along with excessive groundwater pumping and low water table elevations) is a contributor to this troubling phenomenon.
  • The population of Florida is distributed in a highly uneven manner, with 3 out of Florida’s 4 large urban areas situated on the coasts and enormous tracts of sparsely populated land in inland areas.  Due to this pattern of urbanization, the 10 counties in Florida that are most vulnerable to rises in sea level hold 46 percent of the state’s population and are responsible for 57 percent of the state’s personal income.
  • Sea level rise, intricately linked to global warming, is unfortunately not an easy problem to resolve, even if the political will to bring about the necessary changes existed.  Ultimately, to solve this problem we must work to reverse, or at least slow, the processes beyond global warming, though an “easy fix” to minimize the effects of these changes would be less coastal development in Florida.

 

Ultimately, as Floridians and Americans, it is up to each of us to decide if we are willing to take the steps necessary to ensure that our children and their progeny can enjoy the Sunshine State that so many of us take for granted today.

 

References and Works Cited

 

•         “Impacts of a Warming Arctic”, Hassol, Susan J, Arctic Climate Impact Assessment Group, Cambridge University Press, 2004

 

•         “Costal Zones and Sea Level Rise”, Environment Protection Agency, http://epa.gov/climatechange/effects/coastal/index.html, 2006 Oct. 19

 

•         “Saving Florida’s Vanishing Shores”, Florida Environment Protection Agency, March 2002

 

•         “Climate Change and Sea Level”, Weiss and Overpeck, Department of Geosciences, University of Arizona  http://www.geo.arizona.edu/dgesl/research/other/climate_change_and_sea_level/  sea_level_rise/sea_level_rise.htm

 

 

  • “An Inconvenient Truth”, Gore, Albert Jr., Rodale, New York, NY, 2006