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by topography, hydrology and climate. Hydrographic stations are denoted with abbreviations; for
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example, LM for Little Madeira Bay (Table 1). Everglades National Park (green border) covers the
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majority of the region with coastal hydrographic stations in Florida Bay (MK, BK, LM, LS, MD) and
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extending upstream to Taylor Slough (TR, E146, TSH). Urban, suburban and agricultural lands featuring
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water management canal infrastructure can be seen between Everglades and Biscayne National Parks
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(blue border).
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Table 1. Hydrographic stations.
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Station Location Latitude Longitude Water Level Salinity
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BK Buoy Key 25.12111 −80.83356 WaterLog H-331 YSI 600R
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E146 Taylor Slough 25.25252 −80.66626 WaterLog H-331
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LM Little Madeira Bay 25.17580 −80.63269 WaterLog H-331 YSI 600R
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LS Long Sound 25.23516 −80.45680 WaterLog H-331 YSI 600R
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MD South Dade 25.28932 −80.39642 WaterLog H-331 YSI 600R
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MK Murray Key 25.10613 −80.94232 WaterLog H-331 YSI 600R
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TR Taylor River 25.21712 −80.64957 WaterLog H-331 YSI 600R
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TSH Taylor Slough Hilton 25.31073 −80.63100 WaterLog H-331
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J. Mar. Sci. Eng. 2017, 5, 31 3 of 26
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2. Materials and Methods
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2.1. Sea Level Rise Projection
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The Intergovernmental Panel on Climate Change’s (IPCC) most recent evaluation is the Fifth
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Assessment Report (AR5) [8] including projections of global sea level rise based on different
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Representative Concentration Pathway (RCP) scenarios reflecting possible future concentrations
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of greenhouse gases1
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. RCP 8.5, also known as the business-as-usual scenario, is the highest emission
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and warming scenario under which greenhouse gas concentrations continue to rise throughout the
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21st Century, while RCP 6.0 and RCP 4.5 expect substantial emission declines to begin near 2080 and
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2040, respectively.
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The IPCC sea level rise scenarios are comprehensive, but do not include contributions from a
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rapid collapse of Antarctic ice sheets. However, recent evidence suggests that such a collapse may
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be underway [6,7]. In addition, the IPCC projections do not account for local processes such as land
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uplift/subsidence and ocean circulation and do not provide precise estimates of the probabilities
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associated with specific sea level rise scenarios.
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A contemporary study that does estimate local effects and comprehensive probabilities for the
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RCP scenarios is provided by Kopp et al. [9] based on a synthesis of tide gauge data, global climate
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models and expert elicitation, including contributions from the Greenland ice sheet, West Antarctic ice
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sheet, East Antarctic ice sheet, glaciers, thermal expansion, regional ocean dynamics, land water storage
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and long-term, local, non-climatic factors, such as glacial isostatic adjustment, sediment compaction
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and tectonics. Even though this model includes contributions from the Antarctic ice sheets, these
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contributions are from dynamic equilibrium models and do not yet account for an incipient rapid
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collapse as noted above. Nonetheless, we find the Kopp et al. [9] projections to be among the most
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mature and useful sea level rise paradigms and base our South Florida projections on their results at
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Vaca Key, Florida.
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South Florida Sea Level Rise Projection
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Examination of local sea level rise projections around South Florida finds small differences
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between Naples, Virginia Key, Vaca Key and Key West. We chose the Vaca Key station sea level data
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as representative of South Florida since they best reflect local oceanographic processes that influence
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coastal sea levels [10].
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Next, we select the RCP scenario that best fits our understanding for future greenhouse gas
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emissions. Although significant effort is aimed at global emission reduction, atmospheric CO2 and
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emissions continue to escalate [11], and there is presently no clear socio-economic driver to depart
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from a carbon-based energy infrastructure. Further, recent assessments of global energy production
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and population conclude that the the achievement of emission scenarios corresponding to a desired
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2
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◦C limit in global mean temperature increase require the global fraction of Renewable Energy Sources
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(RES) to reach 50% by 2028 [12].
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We note that the International Energy Agency (IEA) reports that global RES could reach 28%
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by 2021 [13]. This is consistent with a 2015 estimate of 24% RES by the United Nations [14] and,
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if accurate, would leave seven years to achieve a near doubling to 50% to meet the Jones and
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Warner [12] constraint. Currently, RES is dominated by hydropower, a resource that is not easily
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scalable or quick to bring online. In the absence of a technological breakthrough, we conclude it is
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unlikely that global RES will reach 50% by 2028. This leads us to expect that the RCP 4.5 emission
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scenario is unobtainable and that there is significant uncertainty as to whether the RCP 6.0 scenario
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can be realized. We therefore restrict our projection to the RCP 8.5 scenario.
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1 The number following RCP quantifies the expected thermodynamic radiative forcing relative to pre-industrial values.
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For example, RCP 8.5 denotes an additional 8.5 W/m2
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thermal forcing from greenhouse gases.
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J. Mar. Sci. Eng. 2017, 5, 31 4 of 26
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Finally, we select conservative projection probabilities appropriate for informing authorities of
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anticipated sea level rise for adaptation and planning purposes. In light of the significant uncertainties
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inherent in the generation of the projections and future climate dynamics, it is prudent to consider
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the upper percentile range of projections leading us to select the RCP 8.5 median (50th percentile) as
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the lower boundary and the 99th percentile as the upper boundary. Although the high projection is
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deemed to have a 1% chance of occurrence under current climate conditions and models, in the event
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of Antarctic ice sheet collapse, this high projection is consistent with estimates of the Antarctic ice melt
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contribution [15].
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The resultant sea level rise projection for South Florida referenced to the North American Vertical
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Datum of 1988 (NAVD88, Appendix A) is shown in Figure 2 and tabulated in Appendix B. Projection
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starting points have been offset to coincide with observed mean sea level in Florida Bay over the
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period 2008–2015 (Appendix C). The projection does not incorporate local processes such as tides,
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storm surges, waves or their non-linear interactions with inundation impacts, issues that are discussed
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in Appendix D.
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Figure 2. South Florida sea level rise projection with respect to 2015 mean sea level in Florida Bay for
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the RCP 8.5 greenhouse gas emission scenario. Units are cm NAVD88. Low projection is the median
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(50th percentile); high projection the 99th percentile. Tides and storm surges are not included in this
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projection. Values are tabulated in Appendix B to year 2120.
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2.2. Inundation Coverage
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Geospatial inundation coverages for mean sea level are created in ArcMap by application of the
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sea level rise projections for the years 2025, 2050, 2075 and 2100 across southern Florida. Topographical
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elevations are based on a synthesis of the best available high-resolution digital elevation data [16] with
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variable spatial resolution, but a nominal horizontal grid cell size of 50 m. The resulting inundation
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coverages represent a static land-masking of mean sea level at the four time horizons and do not
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represent influences from tides, seasonal oceanographic cycles, teleconnections, weather, such as
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storms, or inverse barometric adjustments, as discussed in Appendix D, or for changing morphological
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structure in submerged and inundated sediments or hydraulic connectivity [17]. A review of these
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issues and how the dynamic effects of sea level rise interact with low-gradient coastal landscapes can
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be found in Passeri et al. [18].
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2.3. Water Level and Salinity
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Water levels are obtained from eight hydrographic stations operated by Everglades National
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Park over the period 1 June 1994–31 December 2016 with station locations and names shown in
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Table 1. Water levels are collected at 6-, 15- or 60-min intervals by WaterLog shaft-encoded float gauges
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