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Climate Change and the IRL

The ecological, economic and cultural consequences of climate change are many and far reaching. One of the more pressing issues of climate change, particularly in low-lying Florida, is sea level rise and its potential effects on coastal communities and natural marine ecosystems. The entire state of Florida lies in the Atlantic Coastal Plain with a maximum elevation of 400 ft above sea level. Florida has 2,276 miles of tidal shoreline and the Indian River Lagoon stretches 156 miles along the east central Florida coast.

No one can predict with certainty the extent or timeline of sea level rise to coastal Florida. However, it is now widely accepted that climate change and global warming are occurring and that coastal communities worldwide will be affected. We should all become more aware of the potential impacts of sea level rise well before they occur so that prudent decisions can be reached on how best to deal with and mitigate these impacts at the appropriate time. Let's start with a few basics:

What is climate?

Climate may be thought of as weather patterns (temperature, precipitation, relative humidity, winds, etc.) persisting and averaged in an area over long periods of time (e. g., thousands to millions of years). Climate has affected the evolution of both human history (cultural and economic) as well as the global occurrence of natural ecosystems and regional biodiversity. Weather, on the other hand, describes short-term atmospheric conditions for a particular place and time. Weather conditions, as we all know, may change rapidly and can differ dramatically over short geographic distances.

What is climate change?

Climate change may be defined as significant changes in the measures of climate lasting for extended periods of time (decades to thousands and millions of years).

What are the main drivers of climate change?

Climate change may come about through natural or anthropogenic (human-induced) causes. Natural drivers of climate change include variation in such things as solar output, ocean currents, volcanic activity and the earth's orbit around the sun. Man-induced drivers of climate change mainly have to do with the increased levels of CO2 and other greenhouse gases in the atmosphere, brought about by the burning of fossil fuels, and to a lesser extent, by tropical deforestation, as well as some industrial and agricultural processes.

What is the "greenhouse" effect?

The "greenhouse" effect occurs when greenhouse gases accumulate in the atmosphere (often referred to as a "blanket") preventing incoming solar radiation form escaping. This "trapped" solar radiation is re-radiated back to the earth causing abnormal elevation of the earth's surface temperatures. The average global temperature, for example, has risen by 1.4o F over the past century and is estimated to rise between 2 to 11.5o F over the next one hundred years.

What are greenhouse gases?

The four main green house gases are water vapor, carbon dioxide (CO2), methane and ozone. Increased levels of CO2, from human activities, i.e., the burning of fossil fuels and to a lesser extent, tropical deforestation, are thought to be the major contributor responsible for the greenhouse effect. Since the industrial revolution, CO2 levels in the atmosphere have increased approximately 40 % (from 280 ppm (parts per million) to 392 ppm).

What causes sea level to rise?

It is estimated that sea levels are currently rising at a level of 3 mm/year and that the rate of sea level rise is expected to increase well into the future. The two main factors causing sea level to rise are: 1) the melting of ice sheets and glaciers in polar regions; and 2) to a lesser extent, the thermal expansion of the world oceans associated with increased ocean temperatures. These two factors have led climate scientists to conclude that global climates are warming and they further attribute both phenomena to anthropogenic causes.

What other negative impacts of climate change are there?

In addition to sea level rise, there are many other (ecological, economic, cultural) threats that climate change and global warming may potentially pose: adverse affects on water supplies; changing landscapes and loss of wildlife habitat; threats to natural ecosystems (marine and terrestrial) and biodiversity; higher risk of drought with direct implications for agriculture; increased likelihood of fires and flooding, and more powerful seasonal storms, e.g., Hurricane Sandy.

Sea Level Rise and the Indian River Lagoon:

Surrounded by the Atlantic Ocean and Gulf of Mexico and also inundated by waters from the Everglades, low-lying Florida is particularly prone to climate change and rising sea levels. Further, most of Florida sits on porous bedrock allowing for the infiltration of saltwater. Rising sea levels can also erode beaches, submerge estuaries and low-lying wetlands, enhance seacoast flooding and increase the salinity of estuaries.

As most of us realize, the Indian River Lagoon is one of the most biologically diverse estuaries in the continental United Sates. Its abundance of natural fauna and flora is a result of its geographical positioning overlapping both temperate and sub-tropical biomes with representative species intermingling in a delicate balance. The IRL is also a mosaic of many different types of distinguishable, yet interconnected habitats. Impacts from sea level rise could directly affect the ecology, hydrodynamics, circulation patterns, depth and salinity of this shallow, bar-built, diverse ecosystem:

  • Mangrove communities, occurring along the fringes of intertidal regions throughout most of the IRL, stabilize shorelines and also provide habitat and nursery area for IRL's many ecologically and recreationally important finfish and invertebrates. These mangrove communities have adapted to occupy and maintain their position along the fringes of the lagoon by accreting sediment at a rate in tune with sea level rise when it was occurring at a relatively slow pace. Accelerated sea level rise could pose threat to these vital communities by outpacing their ability to accumulate sediments at appropriate rates.

  • Seagrass beds are indispensible to the overall health and water quality of the IRL. They also provide sediment stabilization and complex habitat. In addition, seagrasses oxygenate the water column, provide substratum for epiphytes and are a food source utilized by manatees, urchins, conchs, some fish and sea turtles. Deeper waters associated with accelerated sea level rise could diminish sunlight levels and adversely impact the photosynthetic capacities of seagrasses leading to substantial decreases in seagrass acreage.

  • Larval stages of some estuarine invertebrate organisms have a narrow range of salinity tolerance. Increased salinity in the lagoon accompanying sea level rise could negatively impact their life histories with consequences affecting their abundance and diversity.

  • Threats to biodiversity: Sea level rise and warmer water temperatures could decrease the number of temperate species that co-occur in the IRL along side the more sub-tropical species; Invasive and other opportunistic organisms could more easily establish themselves under stressful conditions resulting from sea level rise, displacing native flora and fauna.

  • Other impacts of sea level rise: Low-lying upland wetlands and maritime hammocks would also be at risk of drowning and salt water inundation. In many instances, these habitats would have nowhere to retreat because of development along much of the IRL's shoreline. Loss of mud flats and salt marshes (particularly in northern sections of the lagoon) utilized by fish, bird and invertebrate communities is possible. The storm-buffering capacity of barrier islands/dune plant communities along the IRL would also be compromised.

Mapping the IRL Relative to Sea Level Rise:

There are two available reports focusing on the effects of sea level rise relative to shorelines of the Indian River Lagoon: 1) The Impacts of Sea Level Rise to the Indian River Lagoon Estuary, (Florida): An Application of Ecological and Economic Models. Final Report March 2011; and 2) The Likelihood of Shore Protection Along the Atlantic Coast of the United States. Volume 2: New England and the Southeast.

The first report - The Impacts of Sea Level Rise to the Indian River Lagoon Estuary, (Florida): An Application of Ecological and Economic Models. Final Report March 2011 - was prepared for the EPA and Indian River Lagoon National Estuary Program (IRLNEP) to calculate habitat change over time resulting from user-defined increases in sea level. The study uses a model - Sea Level Affecting Marshes Model (SLAMM) and divides the IRL into 4 regions (northern, central, southern and coastal) for model analyses. Using two scenarios (sea level rises of 0.4 and 1.2 meters) played out over three time frames (present, 2050 and 2100) for both unprotected (allowing for wetland migration) and protected, developed lands (blocking wetland migration), the report presents a complete set of detailed maps that provide results at various geographical regions along the IRL in a graphical format from North to South.

The second report, also prepared for the U.S. EPA, contains two sections relevant to sea level rise and the IRL. These sections are available at the following websites:

  1. - focuses on Volusia and Brevard counties;
  2. - focuses on impacts of sea level rise in Indian River, St. Lucie, Martin as well as Palm Beach counties.

These two studies are part of a nation-wide EPA sponsored program to promote planning for and awareness of sea level rise in the context of global climate change among government planners and citizens. The Southwest Florida Regional Planning Council (SWFRPC) was awarded a grant from EPA to participate in the program by coordinating studies of sea level rise in Florida. Consequently the East Central Florida Regional Planning Council (ECFRPC) and the Treasure Coast Regional Planning Council (TCRPC) entered into a contract with SWFRPC to conduct studies within respective coastal regions. Reports include color-coded maps that distinguish shore areas that are likely to be protected from erosion, inundation, and flooding (areas where shore protection is almost certain (brown), likely (red), or unlikely (blue)), and shores where natural shoreline retreat likely will take place (i.e., areas where current environmental policies would preclude shore protection and enable wetlands to migrate inland (light green)).

Relevant Oranizations and Websites (listed alphabetically):

Environmental Protection Agency
This EPA website provides basic information on climate change, green house gas emissions and climate related research as well as information on climate change relative to geographical sections of the United States (e.g., see

Florida Center for Environmental Studies (CES)
CES is a state university research center located at the MacArthur campus of Florida Atlantic University in Jupiter FL. CES is one of the leading institutions in Florida coordinating climate-related research efforts and educational programs and focuses on the Kissimmee River Restoration Project and the Comprehensive Everglades Restoration Plan (CERP). Its ultimate goal is to ensure a sustainable environmental future for Florida. Its website provides current information on news, educational programs, publications and conferences relating to sea level rise issues in Florida.

Florida Climate Center: Office of the State Climatologist
This website provides information on climate relative to Florida by analysis of historical weather observations (1948-present), long-term historical climate averages, and insights into climate trends via the occurrence of El Niño, La Niña events. The website also provides information on extreme weather events including hurricanes and serves as an educational outreach program on current and emerging climate issues.

Florida Climate Institute (FCI)
The Florida Climate Institute (FCI) is a consortium of Florida universities including Florida Atlantic University, the University of Florida, Florida State University, University of Central Florida, University of Miami and the University of South Florida. Its primary goal is to promote a better understanding of climate variability and change in Florida by providing both accurate and reliable climate-related information. FCI also supports scientific research on climate and sea level rise and works with citizen groups to develop an aware and climate-ready workforce knowledgeable in climate risks that are unique to Florida.

Florida Oceans and Coastal Council (FOCC)
The Florida Oceans and Coastal Council was created by the 2005 Legislature through The Oceans and Coastal Resources Act. The Council is charged each year with developing priorities for ocean and coastal research and establishing a statewide ocean research plan.
Please see their comprehensive treatment (i.e., what is known, what is possible, and what is probable) of climate change and sea level rise in coastal Florida, available at:

Integrative Collaborative on Climate and Energy (ICCE)
The Integrative Collaborative on Climate and Energy (ICCE) was created by the Florida Center for Environmental Studies (CES). ICCE's mission is to provide a practical outlet for research findings relative to Florida's natural and urban systems and in so doing, collaborates with university, government and regulatory agencies.

Intergovernmental Panel on Climate Change (IPCC)
IPCC was established by the United Nations Environment Program (UNEP) and the World Meteorological Organization (WMO) in 1998 to provide the world with a clear scientific view on the current state of knowledge in climate change and its potential environmental and socio-economic impacts.

United Nations
The United Nations promotes a global effort to "mobilize action and ambition" on climate change and is convening a summit in September, 2014 to catalyze action by governments, business, finance, industry, and civil society to help the world shift to a low-carbon economy.


The Impacts of Sea Level Rise to the Indian River Lagoon estuary, (Florida): An Application of Ecological and Economic Models. Final Report March 2011. Report to the U. S. Environmental Protection Agency, Washington, DC, and the Indian River Lagoon National Estuary Program, Palm Bay, FL. Industrial Economics, Inc., Cambridge, MA.

Merritt, Peter. 2010. Treasure Coast. In James G. Titus, Daniel L. Trescott, and Daniel E. Hudgens (editors). The Likelihood of Shore Protection along the Atlantic Coast of the United States. Volume 2: New England and the Southeast. Report to the U.S. Environmental Protection Agency. Washington, D.C.