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