A RESOLUTION OF THE MAYOR AND CITY COMMISSION OF THE CITY OF MIAMI BEACH, FLORIDA, ADOPTING THE 2019 UPDATE OF THE UNIFIED REGIONAL SEA LEVEL RISE PROJECTION OF SOUTHEAST FLORIDA AND THE ACCOMPANYING UNIFIED SEA LEVEL RISE PROJECTION, SOUTHEAST FLORIDA; AND FURTHER DIRECTING THE CITY OF MIAMI BEACH TO UTILIZE THE UPDATED REGIONALLY CONSISTENT UNIFIED SEA LEVEL RISE PROJECTIONS FOR PLANNING, DESIGN AND CONSTRUCTION PURPOSES. 

Administration recommends that the City Commission adopt the 2019 update of the Unified Regional Sea Level Rise Projection for Southeast Florida prepared by the Southeast Florida Regional Climate Change Compact (“Compact”) and that Miami Beach continue to utilize the regionally consistent unified sea level rise projections for planning purposes. 

This is a key planning tool produced by the Compact and is intended to assist decision-makers at both the local and regional levels in Southeast Florida.

This is the third update of the Compact’s Unified Sea Level Rise Projection for Southeast Florida that was first developed and released in 2011 and was subsequently updated in 2015.  The City of Miami Beach previously adopted the projection in 2016 through Resolution 2016-29317. The projection is reviewed and updated every five years, or sooner, as a result of ongoing advances in scientific knowledge and modeling via the peer-reviewed literature on global climate change.   

The Southeast Florida Regional Climate Change Compact ("Compact") was created in 2010 to study, promote, and strengthen the economic and environmental resilience of communities in the Southeast Florida region.  In recognition of the need for immediate, coordinated, and visionary action to address the impacts of a changing climate, Miami-Dade, Palm Beach, Broward, and Monroe Counties ("Compact Partners") entered into the Compact.

In 2019, the Compact convened an ad hoc Sea Level Rise Work Group composed of scientific experts to update the projection utilizing recent data since 2015.  The group included the National Oceanic and Atmospheric Administration, the U.S. Department of the Interior, the South Florida Water Management District, the Nature Conservancy, the University of Miami, Florida International University, as well as staff from the four Compact Counties.

On December 9, 2019, the updated projection was shared with the City Commission through Letter to Commission.  The technical workgroup co-chair provided a presentation overview for the City Commission at the January 27, 2020 Commission Retreat.  The full projection document was finalized in February of 2020 and shared with cities in April of 2020.

The City of Miami Beach Comprehensive Plan, adopted by the City Commission on October 16, 2019 (Ordinance No. 2019-4302), Objective 1.1 states objectives to “increase the City’s resiliency to the impacts of climate change and rising sea levels by developing and implementing adaptation strategies and measures in order to protect human life, natural systems and resources and adapt public infrastructure, services, and public and private property. It further defines the use of the Compact Sea Level Rise Projection in Policy 1.1.2: “the City’s basis for measuring sea level rise shall be as per the Southeast Florida Regional Climate Action Plan, as may be revised from time-to-time by the Southeast Florida Regional Climate Change Compact.”

The sea level rise projection is intended to inform sea level rise adaptation strategies and policies, and is offered to ensure projects throughout the Southeast Florida region have the same basis for design and construction relative to future sea level. 

The City of Miami Beach is located at an elevation close to sea level, and the sea level rise projection contains the best available science for the city’s policies and design standards for private property and public infrastructure adaptation to sea level rise. The sea level rise projection informs the City of Miami Beach’s comprehensive resilience strategy, including land use regulations for public, residential, and commercial properties, residential lot grade, building freeboard, stormwater infrastructure, seawalls, historic preservation, and environmental resources.   When examining the projection, it is important to note that the curves are mean, or average, and the additional fluctuations experienced from high tides, King Tides, and storm surge are in addition to the mean projection.

Unified Regional Sea Level Rise Projection for Southeast Florida 2019 Update Overview

As described in the Unified Regional Sea Level Rise Projection (Attachment 1), the 2019 updated projection is based on estimations of sea level rise developed by the Intergovernmental Panel on Climate Change Fifth Assessment Report, as well as projections from the National Oceanic and Atmospheric Administration (NOAA), and accounts for regional effects that produce differences in Southeast Florida’s local rate of sea level rise. This projection uses 2000 as the reference year and it also now extends to 2120. Since 2000, sea level rise has increased at a more accelerated rate than historically seen.

The projection consists of three planning curves as the basis for a Southeast Florida sea level rise projection for the 2040 and 2070 planning horizons. These curves are projected from the year 2000 to 2120:

1. Short term: by 2040, sea level is projected to rise 10 to 21 inches above 2000 mean sea level.

2. Medium term: by 2070, sea level is projected to rise 21 to 54 inches above 2000 mean sea level.

3. Long term: by 2120, sea level is projected to rise 40 to 136 inches above 2000 mean sea level.

4. It should be noted, that a fourth curve, the NOAA Extreme curve, is included for informational purposes, not for application. This more extreme curve illustrates the possible upper limit of sea level rise in response to potential massive ice sheet collapse in the latter part of the century (2070 and beyond). This curve underscores that without imminent and substantial reductions in greenhouse gas emissions, much greater sea level rise is possible more than 100 years from now.

How to Use the Projection for Planning Purposes

The lower blue shaded portion of the projection can be applied to most adaptable infrastructure projects to be replaced before 2070 or projects whose failure would result in limited consequences to others.  Projects in need of a greater factor of safety related to potential inundation or with lower capacity to adapt mid-life should consider designing for the NOAA Intermediate High Curve. For critical infrastructure projects with design lives in excess of 50 years or low capacity to adapt mid-life, the use of the NOAA High curve is recommended with planning values of 54 inches in 2070 and 136 inches in 2120.

It is recommended that the City Commission adopt the 2019 update of the Unified Regional Sea Level Rise Projection for Southeast Florida and accompanying Unified Sea Level Rise Projection, Southeast Florida guidance document and that Miami Beach continue to utilize the regionally consistent unified sea level rise projections for planning, design and construction purposes.