LTC 265-2020 Annual Sea Level Rise Report - 2020D M IAM I BEACH
O FFIC E O F TH E C ITY MA N A G ER
N O . LTC #
TO : Mayor Dan Gelber and Members of; the City C
LETTER TO COMMISSION
FRO M : Jimmy L. Morales, City Manage
D A TE: July 22, 2020
SU BJEC T : Annual Sea Level Rise Report -
On July 25, 2018, the Mayor and City Commission passed resolution (2018-30418) directing the
administration to collect and track on an annual basis, sea level rise data from the Virginia Key
tidal gauge and from the Southeast Florida Regional Climate Change Compact (Compact) (or
from an alternative preferred data source, if one becomes available) and to annually report such
data to the City Commission in order to facilitate an incremental adaptation strategy (Attachment
A). In accordance with the resolution, the requested historical data from the Virginia Key tidal is
provided below. In February 2020, the Compact released the 2019 update Unified Sea Level
Rise Projection for Southeast Florida, which will be brought to the Mayor and City Commission
for adoption to be used for planning purposes at the July 24, 2020 special commission meeting.
Background
The National Oceanic and Atmospheric Administration's Center for Operational Oceanographic
Products and Services (CO-OPS) maintains the National Water Level Observation Network. This
network includes more than 200 permanent water level stations throughout the United States that
allow NOAA to provide official tidal predictions for the nation. The Virginia Key tide station has
been collecting local sea level trends since 1931. Exhibit 1 illustrates the monthly mean sea level
without the regular seasonal fluctuations due to coastal ocean temperatures, salinities, winds,
atmospheric pressures, and ocean currents. The relative sea level trend is 2.92 mm/yr with a 95%
confidence interval of+/- 0.22 mm/ yr based on monthly mean sea level data from 1931 to 2019,
which is equivalent to a change of 0.96 feet in 100 years (www.tidesandcurrent.noaa.gov).
8723214 Virginia Key, Florida 2.92 + /- 0.22 mm /yr
0.60 r
Linear Relative Sea Level Trend -~
- Upper 95% Confidence Interval (~; _
Lower 95% Confidence Interval
Monthly mean sea level with the
a/Ia Seasonal de fem1oed l- - -
0.45
0.30°
0.15
"' • o.o0o
du
::E
-0.15/
-0.30
-0.45/
~ - - - - -
-0.60 )!===================--================= 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010 2020
Exhibit 1: Relative Sea Level Rise Trend - Virginia Key, Florida
South Florida Climate Change Compact's Unified Sea Level Rise Projection
In 201 O, the South Florida Climate Change Compact (Compact) was formed to coordinate
mitigation and adaptation between Monroe, Miami-Dade, Broward, and Palm Beach Counties. In
2011, the Compact released the first regionally unified sea level rise projection. The Compact
created the ad hoc Sea Level Rise Work Group composed of scientific experts within the
academic community, as well as staff from local, regional, and federal government to update the
regional projection at regular intervals. Following the first report, the projection and accompanying
guidance report has been updated in 2015, and most recently in 2019. The 2019 update and
accompanying guiding document will be going to the Commission of adoption on July 24, 2019.
The Com pact's ad hoc Sea Level Rise Work Group updates the Unified Sea Level Rise Projection
for Southeast Florida based on the latest scientific understanding of climate change and sea level
rise for the region. Climate science is rapidly advancing, generating new, peer-reviewed literature
and modeling, including the Intergovernmental Panel on Climate Change (IPCC) Fifth
Assessment Report (IPCC, 2014), the National Oceanic and Atmospheric Administration (NOAA),
and the U.S. Army Corps of Engineers (USAGE) models. The Unified Sea Level Rise Projection
for Southeast Florida accounts for regional effects, such as gravitation effects of ice melt, changes
in ocean dynamics, vertical land movement, and thermal expansion from warming of the Florida
Current that produces regional differences in Southeast Florida's rate of sea level rise compared
to global projections. The Compact updates the projection and guiding document at least every
five years in order to provide current guidance for regionally consistent sea level rise planning
and decision-making. It is recommended that the City continue to utilize the most recent Unified
S e a L e v e l R is e Proje c tio n fo r S o u th e a s t Fl o rid a fo r planning and infr astructure siting and design
pu rp o se s w hen co n sid e rin g both sho rt - and lo ng-term planning horizons.
200
2 1 8 0 o
-1 O u. (y
; t16o
@ e z >- 140 a c • >
• Q)
3;120
• d n
2 e 10o o ro
a)
22s
4t
ro d
8 6o
±%
± 4o a d r: u
e 20
Unified Sea Level Rise Projection
(So u th e ast Flor ida Reg ion al Clim ate Change Compact, 2019)
m p
Year
2040
2070
2120
Observed
5-Year Average
Mean Sea level
IPCC N O AA
Median Intermediate
(in ches) High
ynche]
10 I 17
21 I 40
40 92
N O AA High
(inch es)
21
54
136 NOAA High
136
92
Intermediate High
1990 2000 2010 2020 2030 2040 2050 2060 2070 2080 2090 2100 2110 2120
Year
NOAA
Exhibit 2: Southeast Florida Regional Climate Compact Unified Sea Level Rise Projection (2019)
Conclusion
T h e S o u thea st F lorid a R e g ional C lim a te C om pa ct updates the sea level rise projection at
m in im u m eve ry five yea rs to refle ct the ong o ing advances in scientific know ledge related to global
clim a te cha n g e. A t the spe cia l co m m issio n m e eting on July 24, 2020 there is a resolution to adopt
th e Unified Sea Level Rise Projection for Southeast Florida and that M iam i Beach continue to
utiliz e the reg io na lly co nsistent un ifie d sea le vel rise projection fo r planning purposes. The
A d m in is tra tion re co m m end s that future sea level rise updates be pro vided w hen the Unified Sea
Level Rise Projection for Southeast Florida is upd ated.
JL M /A T H /A K/E S W
A tt a chm ents:
A. R e so lu tion 2018 -3 0418
B . 20 19 U n ifi e d Se a Level R ise Pro je ct fo r Southeast Florida