The Compact Releases its 3rd Regionally Unified Sea Level Rise Projection

December 18, 2019

At the 11th Annual Climate Leadership Summit hosted in Key West Dec. 3-5, the Compact released its third update to the Regionally Unified Sea Level Rise (SLR) Projections for Southeast Florida. The Compact first produced a Unified SLR Projection in 2011 in response to the multiplicity and diversity of local SLR projections—a barrier to achieving regionally consistent adaptation strategies and policies, as well as effectively influencing supportive policies at the state and federal levels. The 2019 projection builds upon the last update in 2015. The Compact updates the projection every five years or sooner based on newly available, peer-reviewed literature and climate modeling that informs an ad hoc SLR Work Group, consisting of experts from the academic community, federal agencies, and local government staff.

The 2019 Projection shows slightly higher curves overall, given the rate of ice sheet melt and the incorporation of regional effects. For example, if we compare the curves suggested for buildings or long-lasting infrastructure, 2015 USACE High and 2019 NOAA Intermediate High curve at 2060, we would see a 5” increase in projected SLR in this projection versus the last projection released. Another key difference in the updated Projection is an extended planning horizon—shifting to 2040, 2070, and 2120 in alignment with the release of climate scenarios extending beyond the century by federal agencies, and the need to plan infrastructure with design lives greater than 50 years. The 2019 projection indicates:

  • In the short term, by 2040, sea level is projected to rise 10 to 17 inches above 2000 mean sea level. 
  • Medium term, by 2070, sea level is projected to rise 21 to 54 inches above 2000 mean sea level.
  • Long term, by 2120, sea level is projected to rise 40 to 136 inches above 2000 mean sea level.

Additionally, the Projection now contains a fourth curve, to include the NOAA extreme curve (dashed curve) for informational purposes bracketing the upper range of possible sea level rise under an accelerated ice melt scenario in the latter part of the century. While the graphic may appear more complicated with four curves rather than three, there is still a high confidence in the blue shaded zone out to 2070, recommended for planning most projects with a short-planning horizon. Looking beyond the century, the spread of the potential scenarios indicate how critical aggressive, immediate emission reductions are for the future of the region. 

The SLR Projection has become a cornerstone for regionally-consistent planning to inform adaptation strategies, policies, and infrastructure design across the Southeast Florida region. The Compact plans to release an accompanying guidance report to support the updated SLR Projection in January 2020.