Key Biscayne: An Island Paradise in Jeopardy?

Julie Lambert, Teaching and Learning, Florida Atlantic University


The Village of Key Biscayne is located in Miami-Dade County on the island of Key Biscayne. It is located ~5 miles off the coast of Miami across the Biscayne Bay. According to the United States Census Bureau, the village has a total area of 1.4 square miles (3.6 km2). Crandon Park, a Miami-Dade County Park, is located at the northern end of the island and Bill Baggs Cape Florida State Park at the southern end. According to the 2010 U.S. Census, Key Biscayne has a population of 12,344. The Island Life 14 Official Guide and Directory of the Key Biscayne Chamber of Commerce reports that ~80% of the residents speak a language other than English at home, ~4,256 households ranging from ~$300,000 to $20,000,000, and a median household income of $104,554.

Most of Key Biscayne is less than 5 feet above sea level. Some locations are above 5 feet, mostly in fill areas or along the Atlantic Ocean side. The island is the southernmost sandy barrier island on the Atlantic coast of the U.S. The geology of Key Biscayne is important for understanding the need to address the risk and vulnerability of the island.

About 3200 years ago, sea level rise slowed down and the barrier island could be stable and grow. Most of Key Biscayne grew over past 2,300 years as sand drifted from the north, mostly during winter storms, and was deposited on the limestone ridge running up the southeast coast of Florida. This southward movement of sand and the protection of the islands of Bahamas has caused Key Biscayne to maintain its fairly stable shape. One modification has caused Key Biscayne to become "sediment starved" over the past 100 years. When Government Cut was dredged create a deepwater port for Miami, sand often drifted into the cut causing boats to ground. A barrier was built at the south end of Miami Beach to prevent this movement of sand. Sand has therefore, not moved southward to feed Virginia Key and Key Biscayne.

Because of the porous limestone and the temporary nature of sand, Key Biscayne is very vulnerable to sea level rise of even 1 foot (Figure 3). Sea level has risen 9 inches since 1930. According to Harold Wanless, Chair of Geological Sciences at University of Miami, this is over 8 times the rate of sea level rise that built Key Biscayne. The Southeast Florida Regional Compact is planning for a sea level rise of 3-7 inches by 2030 and 9-24 inches by 2060. Key Biscayne is also using this projection in planning. With a 4 to 5 foot rise or a rapid rise, Key Biscayne, a sandy barrier island, would not be able to rebuild itself.

What is Being Done
The "Village Goes Green Initiative" (VGGI) began in 2007. In the same year, the mayor also endorsed the U.S. Mayors Climate Protection Agreement. Beginning in 2013, Mayor Caplan revitalized the VGGI. Since then, the Green Committee began meeting on a regular basis and the mayor has established a Citizen Science Program. The committee developed the Key Biscayne Sustainability Plan: Laying the Foundation for an Eco-Conscious Tomorrow. This document was last revised on April 7, 2014.

Individuals with expertise/responsibilities in the following areas have helped create the case study:
The Village key players locally include the major, Franklin Caplan and the six other Village Council Members, as well as the Green Committee. Other key players are involved in the Southeast Florida Regional Compact. Miami-Dade Steering Committee members include Nicole Hefty, Joe Rasco, Mark Woerner, Debbie Griner, Paul Voight. There are also several local scientists (i.e., Harold Wanless, Brian Soden, John VanLeer) who can provide expertise.

Key teaching points:
  • The Next Generation Science Standards include several relevant core disciplinary ideas. One example is ERS1.B: Developing Possible Solutions.
  • When evaluating solutions, it is important to take into account a range of constraints, including cost, safety, reliability, and aesthetics, and to consider social, cultural, and environmental impacts. (secondary to HS-ESS3-2),(secondary HS-ESS3-4).
Key teaching points include the following:
  • Importance of understanding the past geologic history of Key Biscayne and how vulnerable the island is to hurricanes, sea level rise, and human modification.
  • The impacts of sea level rise on the islands water supply, frequency of flooding and beach erosion.
  • The current and potential economic impacts (positive and negative).
  • How to develop a sustainability plan for a community.

How this example is used in the classroom:

The sea level rise viewer at could be used to identify vulnerable areas on the island. Students could use a mapping tool, such as Google Earth or ArcGis to identify the vulnerable structures and natural areas based on the projected sea level.

The presentation, The Ever-Changing River of Sand: How Key Biscayne and Virginia Key Formed and Where They Are Headed, by Harold Wanless to the community of Key Biscayne in April of 2008. It provides historical overview of the geology of Key Biscayne and the potential impacts of sea level rise.
The sustainability plan developed for Key Biscayne can serve as a model for students.


Supporting Files

Key Biscayne: An Island Paradise in Jeopardy? (Microsoft Word 2007 (.docx) 1.1MB Apr12 14)
Sea Level Rise Projections for Key Biscayne (Microsoft Word 2007 (.docx) 3.5MB Apr12 14)
Key Biscayne Sustainability Plan (Acrobat (PDF) 2.9MB Apr12 14)