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Sea Level Rise in Miami Beach: Vulnerability and Real Estate Exposure

Zella Ann Conyers University of Miami

Richard Grant University of Miami and University of Johannesburg

Shouraseni Sen Roy University of Miami

Sea level rise threatens coastal communities throughout the United States, and South Florida is on the front line. The iconic and built-up city of Miami Beach, Florida, has a well-developed, high-value property market, and the municipality has been lauded for proactively taking action to adapt to anticipated sea level rise. Moving beyond hyperbole and piece- meal evidence, we compile a comprehensive inventory of adaptation and mitigation measures implemented by various municipal agencies. We employ these data sets to measure exposure and readiness for the entire city and make a prelimin- ary effort to develop a city vulnerability index. Our findings reveal that exposure throughout the city is high and that readiness is concentrated near stormwater drainage systems, leading to high vulnerability along the coast. When we com- pare the spatial patterns of the vulnerability index and the residential property values, we find a mismatch. The most vul- nerable regions are characterized by high income, transiency, and an apparent unresponsiveness to sea level rise. No doubt our findings illustrate a lag effect, but if sea level rise increases, the real estate market could reach a tipping point unless state and federal agencies also fund more comprehensive adaptation. Key Words: exposure, Miami Beach, property val- ues, readiness, sea level rise, vulnerability.

海平面升高威胁了美国各地的沿海社区, 而南佛罗里达便位于此一趋势的前沿。佛罗里达迈阿密海滩具代表性且建筑物密 集的城市, 拥有高度发展且高价的地产市场, 且市政府因主动採取措施应对预期的海平面升高而受到讚扬。我们超越夸张 的说词和零碎的证据, 彙整众多市政单位所施行的调适与缓解措施之广泛清单。我们运用这些数据集来测量整个城市的暴 露与准备就绪程度, 并初步尝试建立城市的脆弱性指标。我们的研究发现揭露, 整个城市的暴露程度相当高, 而准备集中于 暴风排水系统周遭, 导致沿海地区的高度脆弱性。当我们比较脆弱性指标的空间脉络和房地产价值时, 我们发现其中存在 着不协调。最为脆弱的区域具有高所得、变幻无常等特徵, 并明显对海平面升高反应迟钝。我们的研究发现无疑描绘出延 滞效应, 但若海平面升高持续增加, 房地产市场将可能到达一个临界点, 除非州与联邦政府同时资助更为综合性的调适方案。 关键词：暴露, 迈阿密海滩, 地产价值, 准备就绪, 海平面升高, 脆弱性。

El ascenso del nivel del mar amenaza las comunidades costeras a trav�es de todos los Estados Unidos, y el sur de la Florida se encuentra en la l�ınea frontal de esta situaci�on. La ic�onica y muy construida ciudad de Miami Beach, Florida, tiene un mercado de finca ra�ız bien desarrollado y valioso, y la municipalidad ha sido elogiada por tomar acciones cautelosas a fin de adaptarse al ascenso previsto del nivel del mar. Avanzando m�as all�a de la hip�erbole y de la evidencia fragmentaria, com- pilamos un amplio inventario de medidas de adaptaci�on y mitigaci�on implementadas por varias entidades municipales. Usamos estos conjuntos de datos para medir la exposici�on y presteza para el total de la ciudad y acometimos un esfuerzo preliminar para desarrollarle un �ındice de vulnerabilidad. Lo que descubrimos indica que la exposici�on es alta a trav�es de la ciudad y que la presteza se concentra cerca de los sistemas de drenaje de aguaceros tormentosos, lo que conduce a una muy alta vulnerabilidad a lo largo de la costa. Al comparar los patrones espaciales del �ındice de vulnerabilidad y los valores de la propiedad residencial, se nota una discordancia. Las regiones m�as vulnerables est�an caracterizadas por altos ingresos, transitoriedad y una aparente indolencia ante la perspectiva de un ascenso del nivel del mar. Indudablemente nuestros hal- lazgos ilustran un efecto de rezago, pero si el aumento del nivel del mar se incrementa, el mercado de finca ra�ız podr�ıa alcanzar el punto de crisis a menos que las agencias estatales y federales financien una adaptaci�on de mayor amplitud. Palabras clave: ascenso del nivel del mar, exposici�on, Miami Beach, presteza, valores de la propiedad ra�ız, vulnerabilidad.

The natural and human-made barrier islands andpeninsula of Miami Beach are on the front line of climate change. The city’s flat coastal topography,

largely surrounded by water but connected to the mainland by several bridges, roadways, and high- ways, makes it a major target of the effects of sea

The Professional Geographer, 71(2) 2019, pages 278–291 # 2019 American Association of Geographers. Initial submission, February 2018; revised submission, June 2018; final acceptance, June 2018.

Published by Taylor & Francis Group, LLC.

level rise (SLR). Some direct effects of the invading sea on the City of Miami Beach (CMB) are well docu- mented; for example, extreme flooding during king tides,1 daily inundation, and coastal erosion (Treuer 2017). Research shows that, after 2006, flooding from rain-induced events increased by 33 percent and flooding from tide-induced events increased by more than 44 percent (Wdowinski et al. 2016). Indirect effects such as the impact on current and future prop- erty values and the real estate market are under- studied. In this article, we study the highly urbanized coastal community of the CMB to assess how the city and county are anticipating and dealing with impend- ing SLR and examine whether vulnerability to SLR has a direct effect on property values.

The CMB’s experiences could be a precursor to what might transpire in many other coastal commun- ities in the United States. Specifically, South Florida is expected to experience a 0.45- to 1.8-m (1.5–6.0 ft) increase in SLR by 2100, which will affect drainage, groundwater levels, saltwater intrusion, storm surges, and flooding (Ruppert and Grim 2013; Southeast Florida Regional Climate Change Compact Sea Level Rise Work Group [Compact] 2015; Sweet et al. 2017; Wanless 2017). Recent data show that SLR in south- east Florida increased 20mm/year (0.78 inches) from 2011 to 2012 (Prasad 2016; Valle-Levinson, Dutton, and Martin 2017). Anticipating the necessity for coor- dinated action, four counties of southeast Florida (Miami–Dade, Broward, Palm Beach, and Monroe) joined in 2010 to form the Southeast Florida Regional Climate Change Compact,2 resulting in the creation of the Regional Climate Action Plan in 2014. The compact and action plan identify various mitiga- tion and adaptation strategies.

Since 2013, the CMB has transitioned from a lag- gard to an aggressive implementer of new adaptation measures (Treuer 2017). It is at the vanguard, one of only a few municipalities in the United States to have implemented both short- and long-term climate adap- tation measures to improve resilience (Compact 2015). A major effort culminated in the CMB establishing a Sustainability and Resilience Committee in 2015 and developing its Sustainability Plan3 to channel resour- ces, prevent harm to the natural environment, protect human health, and benefit the overall well-being of the community for present and future generations. This plan aims to protect properties throughout the CMB, which encompasses some of Miami’s most expensive real estate (CMB 2015). Increased sustainability and community resilience is to be enhanced by identifying relevant indicators, establishing targets, and imple- menting initiatives. Several measures such as restoring natural resources, urban reforestation, flood plans, and green infrastructure specifically target the direct effects of SLR (Figure 1).

With a current population of more than 91,000 residents and with more than 7 million tourists with rental and vacation properties, the CMB has a total

real estate value in excess of US$30 billion (CMB 2016; Treuer 2017). With the entire city less than 3.0 m above sea level and with the vast majority of residential development built on land less than 1.8 m above sea level, CMB property owners should be among the first to deal with the effects of the invad- ing sea on their properties’ values (CMB 2016).

The insurance industry estimates that Miami has one of the highest total values of real estate under threat of any city in the world (Melillo, Richmond, and Yohe 2014). A dearth of research assessing whether property values are changing specifically due to the effect of impending SLR prevailed until a 2018 increase in research on this relationship (Bernstein, Gustafson, and Lewis 2018; Keenan, Hill, and Gumber 2018; McAlpine and Porter 2018). Keenan, Hill, and Gumber (2018) put forward a “climate gen- trification” hypothesis, showing that rates of property appreciation at the lowest levels of elevation have not kept up with rates of appreciation with incremental measures of higher elevation in Miami–Dade. Another county-level study (McAlpine and Porter 2018, 1) indi- cates that properties at the water’s edge “projected to be completely flooded by 2032 are losing US$3.08 each year per square foot of living area.” Bernstein, Gustafson, and Lewis (2018) also reported in a coastal U.S. study that homes exposed to SLR sell for approximately 7 percent less than equivalent unex- posed properties equidistant from the beach. The topic of SLR, risk, and exposure is also garnering new atten- tion; for example, Jupiter (see http://jupiterintel.com), a Silicon Valley startup, aims to test climate change calculating software in Miami; First Street Foundation, a nongovernmental organization, is developing an interactive online platform to aid in understanding flood risk (see https://floodiq.com/#); and Zillow Research (2018) publishes basic “rising sea level” data at the county level for three tiers of home values.

Our study on the CMB is based on assembling a comprehensive data set on various adaptation and mitigation measures for the entire urban area. Motivated to move beyond media hyperbole (e.g., a Rolling Stone article titled “Goodbye Miami” raised the specter of the disappearance of Miami and its turning into “An American Atlantis”; Goodell 2013, 1), we advance a more robust geographical analysis and assessment beyond elevation and other piece- meal evidence. Given Miami’s population, economic size, and climatic exposure (Kanai, Grant, and Jianu 2017), research on the city and its impending SLR is highly important. We therefore undertake a com- prehensive analysis of various measures to mitigate the impacts of SLR, such as stormwater drainage, green buildings, coastal monuments, artificial reefs, seagrass beds, mangroves, seawalls, and dune restor- ation. Some of the data (e.g., seawalls) are being incorporated for the first time in research on this area. We move beyond relying exclusively on

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elevation, which provides a rather limited assessment of the impacts and vulnerability to invading seas.

The next section of this article details the mitiga- tion and adaptation efforts throughout the CMB. Then we move on to discuss the data and methods employed in constructing a vulnerability index for the CMB. We examine the spatial patterns of this index in the context of mitigation and adaptation measures with reference to residential real estate val- ues in the aftermath of the post-2009 real estate market crash. We evaluate whether the real estate market incorporates a price gradient in terms of

exposure, readiness, and preparedness for SLR. Finally, we conclude with some preliminary observa- tions about vulnerability exposure and residential development in the CMB and consider some ways to productively refine the vulnerability index

Our study is informed by the perspective that measures to mitigate and adapt to SLR augment the residential real estate market in the CMB. The com- bination and spatial extent of these measures play an important role in reducing risk, both perceived and real. Some literature speculates on coastal prop- erty values decreasing with SLR, but little is known

Figure 1 General layout of the study area, City of Miami Beach. Base map source: ESRI, Digital Globe, Geoeye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AeroGRID, IGN, and the GIS User Community. USDA = U.S. Department of Agriculture; USGS = U.S. Geological Survey; GIS = geographic information system. (Color figure avail- able online.)

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about the timing and possible herding effect and whether the real estate industry will change tack and move away from promoting coastal sites toward encouraging properties at higher elevations. Focusing on the present, we do not know whether current mitigation and adaptation techniques have any effect on maintaining property values.

Data and Methods

Our approach for contending with accelerating SLR is informed by paradigms of comprehensive adapta- tion planning and iterative adaptive risk manage- ment (Butler, Deyle, and Mutnansky 2016). Adaptation measures are based on hazard assessment intelligence, economic, and political contexts. The CMB, like most Florida cities, establishes its approach on low-regrets incrementalism and experi- mentation rather than on implementing bold adap- tation initiatives (Butler, Deyle, and Mutnansky 2016). For instance, the city considered proposals to build a 61-m subterranean wall around Miami Beach, to remove stormwater with deep water injec- tion wells, and to convert streets to canals, but these proposals were deemed too expensive and long- term. Instead, the city opted to focus on short-term risk (within a decade) to provide immediate support to the real estate market. It hired a chief resilience officer and a deputy city manager in 2015 to help manage the complex task of SLR adaptation. Institutional support was also bolstered by the CMB, along with the City of Miami and Miami–Dade County, when they participated in the Rockefeller Foundation’s 100 Resilient Cities in 2016, signaling another benchmark of coordination between the cities and county (Treuer 2017).

An array of initiatives and plans including but not limited to the Regional Climate Action Plan,

CMB Matrix, and the CMB Sustainability Plan is used by the city to frame and guide its adaptation to SLR. Mitigation and adaption measures included in this study are based on common approaches identi- fied in the adaptation and resilience literature (Treuer 2017). For example, prominent mitigation techniques implemented include stormwater man- agement, and important adaption techniques involve an array of green infrastructure, seawalls, and artifi- cial reefs.

Spatial Patterns of Vulnerability in the CMB To assess the spatial patterns of vulnerability in the CMB (Figure 1), we analyze various indicators of exposure and readiness to SLR. Our research is informed by the University of Notre Dame’s Global Adaptation Initiative (ND-GAIN), which created a country-level index using data to measure risk and readiness to climate disruption. This index has been extensively employed in climate adaptation assess- ments (e.g., Busby et al. 2014; Lesnikowski et al. 2015; Donner, Kandlikar, and Webber 2016). Although national areas are important for assessing the impacts of climate change, we adapt this approach to the urban scale because cities play a key role in cli- mate change adaptation. Thereby, employing the ND-GAIN methodology and using comprehensive urban data on the CMB enable a detailed analysis of vulnerability and its relationship to property values.

Based on the levels of exposure and readiness, the final vulnerability scores at the local level are calculated for the CMB using the technique devel- oped by ND-GAIN (Chen et al. 2015). The differ- ent indicators used for the creation of the vulnerability scores are described next.

Exposure Surface Exposure is measured by the extent to which a community is stressed by changing

Figure 2 Indicators of exposure in the City of Miami Beach: (a) elevation 5-m spatial resolution, (b) distance from the coast, and (c) FEMA flood zones. FEMA = Federal Emergency Management Agency.

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climate conditions (Chen et al. 2015). CMB expos- ure levels were measured by three indicators: eleva- tion, distance from the coast, and flood zones identified by the Federal Emergency Management Agency (FEMA). As is common in most SLR stud- ies, elevation is employed as an exposure indicator because it is widely employed to help quantify the potential effects of predicted SLR. We note that the accuracy of the coastal elevation mapping directly affects the reliability and usefulness of SLR impact assessments (Titus 2009). Elevation data were down- loaded from the Florida Geographic Data Library, which is a composite digital elevation model (DEM) created from LiDAR data in 2013 by the University of Florida’s GeoPlan Center for SLR research. The elevation ranged between 7,772 mm (306 in.) above and –24.5 mm (–1 in.) below sea level with a spatial resolution of 5 m (Figure 2a).

Distance from the coast was also used as an indi- cator because it is identified as a key variable affect- ing coastal vulnerability by the U.S. Geological Survey (USGS) in the National Assessment of

Coastal Vulnerability to Future Sea Level Rise (USGS 2000). In the CMB, the total coast-to-coast distance is about 1.8 km (1 mile) wide, and most of the residential development is about 0.46 km (0.25 mile) from the coastline (Figure 2b). FEMA flood zones were employed as an indicator of vul- nerability because of their use by the insurance industry to determine risk (FEMA 2017; Figure 2c).

An exposure surface (Figure 3a) was created by adding weights to each variable, based on discussions with local resilience officers and the CMB planners (Table 1).4 We scored elevation the highest because of its importance in the prediction of SLR. Distance from the coast is scored second highest, and FEMA flood zones are scored lower but are also important as they are factored into risk and real estate calculations.

Readiness Surface Readiness is measured by con- sidering a community’s ability to leverage invest- ment in adaptation (Chen et al. 2015). Indicators for readiness include the portfolio of mitigation and adaptation measures implemented throughout the CMB to combat the causes and effects of SLR (CMB 2018).

The CMB adopted a new Citywide Storm Water Management Master Plan in 2012 (CMB 2012) and subsequently allocated US$500 million for this infrastructural investment (Treuer 2017). The plan identifies adaptable and sustainable stormwater man- agement solutions to help improve flooding condi- tions, to mitigate the effects of sea level increases, and to conserve water. Data on stormwater drains and seawalls are mapped, both highlighted in the master plan to help with flooding and storm surges

Figure 3 Spatial patterns of (a) exposure, (b) readiness, and (c) vulnerability index zones across the City of Miami Beach. Exposure and readiness surfaces are measured on a scale from 1 to 10, scoring exposure and readiness from low to high. Vulnerability is defined in zones from 1 (high) to 4 (low).

Table 1 Weighting scale used for different indicators for the calculation of exposure scores in the City of Miami Beach based on methodology used in previ- ous literature

Exposure map indicators Weights

Elevation 5 Distance from coastline 4 Federal Emergency Management Agency flood zones 1

Note: The total of all weights sum up to 10. Source: Gornitz (1991), Gornitz et al. (1994), and City of Miami Beach (2015).

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(Figures 4a and 4b). Six types of stormwater struc- tures are used in the CMB: catch basins, drainage wells, hydraulic structures, manholes, percolation test sites, and vertical French drains. Some 111.1 km (60 miles) of seawall surrounding the CMB helps protect from storm surges and SLR and prevent soil erosion (Figure 4b). Moreover, the CMB created a new seawall standard in 2014, raising the minimum height to 1.7 m (5.7 ft; CMB 2015).

One of the highlights of the CMB Sustainability Plan is the encouragement of green buildings. Existing initiatives highlighted in the plan include the Green Building Ordinance and the Florida Energy Conservation and Sustainable Buildings, which require most city buildings and encourage other buildings to become Leadership in Energy and Environmental Design (LEED) certified (CMB 2015). LEED-certified buildings are defined as those that are resource efficient; that is, they use less water and energy and reduce greenhouse gas emis- sions. Building locations were retrieved from the U.S. Green Building Council Web site (https://new. usgbc.org/). Of the forty-three LEED buildings under development in 2017, only one building at this time is classified as Platinum (Figure 4c).

Green infrastructure data include artificial reefs, seagrass beds, coastal monuments, and mangroves. Artificial reefs are human-made and mimic natural reefs with the ability to diffract wave energy and even catastrophic waves caused by hurricanes. Artificial reefs are constructed from an array of materials, including but not limited to steel, con- crete, and fiberglass (Baine 2001). The Miami–Dade County Artificial Reef Program was established in

Figure 4 Indicators of readiness in the City of Miami Beach: (a) stormwater drain locations, (b) seawalls, (c) green build- ings, (d) artificial reefs, (e) monument locations, (f) dune restoration areas, (g) mangrove locations, and (H) seagrass bed locations.

Table 2 Weighting scale used for different indicators for the calculation of readiness scores in the City of Miami Beach based on an established methodology

Readiness map indicators Weights

Stormwater drainage 1.75 Green buildings 0.50 Coastal monuments 0.75 Artificial reefs 1.75 Seagrass beds 0.50 Mangroves 1.50 Seawalls 2.00 Dune restoration 1.25

Note: The total of all weights sum up to 10. Source: Gornitz (2000), Wilbanks et al. (2007), Bolton (2009), and City of Miami Beach (2012, 2015).

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1981, although efforts to construct reefs began five decades earlier (CMB 2015). The reefs extend 65 km (35 nautical miles) along the coast of Miami–Dade, and seventy-two artificial reefs are located within 9.2 km (5 miles) of the CMB (Figure 4d).

Coastal monument locations erected by the Florida Department of Environmental Protection (FDEP) extend along the entire coast of the state of Florida. Functioning as coastal monitoring sites, topographic profiles are collected annually to assist in monitoring beach quality (FDEP 2017) and in determining areas of beach nourishment, erosion, and so on. There are forty-five costal monument locations along the coast of the CMB (Figure 4e). Dune restoration areas also informed the readiness map due to their effects on stabilizing sands, mini- mizing erosion, and blocking storm surges. Four of these areas stretch along the east coast of the CMB (Figure 4f). Dune restoration data were created from the maps provided in the Beachfront Management Plan from the CMB (CMB 2016).

Mangroves are important to coastal communities because of their ecological and socioeconomic serv- ices, specifically protecting coastlines from erosion and storms as well as acting as sinks for sediments (Kumara et al. 2010). Mangroves are mostly located north and south of the CMB (Figure 4g). Seagrass beds also play an important role in sediment reten- tion and the mitigation of coastal erosion (Field,

Hempel, and Summerhayes 2002). A large range of seagrass bed restoration sites exist within 1.85 km (1 mile) of the CMB. Seagrass beds surround the west side of the city and are consistently maintained and restored (Figure 4h). Data for these variables were collected from the FDEP and their Office of Coastal and Aquatic Managed Areas.

The readiness surface (Figure 3b) was created by adding weights to each variable based on discussions with local resilience officers and the CMB master plan (Table 2). Seawalls were weighted highest because of the immediate protection against flood- ing as well as their low maintenance costs (CMB 2015; Kraus 2017). Stormwater drains, mangroves, and artificial reefs were weighted second highest because of their effectiveness in helping to combat the impacts of SLR and because of their low main- tenance and installation costs (Kumara et al. 2010; Baine 2011; CMB 2015). Green buildings were ranked the lowest because of their localized benefits to one property rather than the community. Other indicators were ranked based on effectiveness and cost. Distance from each of these indicators was cal- culated for the final readiness surface.

Vulnerability Surface Vulnerability is defined as the propensity of society to be negatively affected by climate hazards (Chen et al. 2015). It is based on levels of exposure and readiness of a community; by

Figure 5 Decadal-level development of residential properties in the City of Miami Beach from 1900 to 2017.

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using the ND-GAIN equation we develop a vulner- ability scale for the CMB:

Vulnerability ¼ ðReadiness–Exposure þ 1Þ � 50:

Vulnerability is calculated by subtracting the weighted scores of readiness from exposure, and the scores were scaled to determine a value from 0 to 100. The vulnerability surface was classified into four zones using natural breaks, with Zone 1 desig- nated as the most vulnerable and Zone 4 the least vulnerable (Figure 4c). In this study, we took into consideration both biophysical and socioeconomic factors to assess vulnerability.5

Property Values Property values for CMB (2009–2017) were obtained from the Office of the Miami–Dade County Property Appraiser. Of a total of 754,294 property records, 462,989 were residen- tial transactions (Figure 5). Property values rose to US$360 million during the time period. To under- take a comparative analysis, we calculated the dollar value/km (ft2). The average property value is US$91,000, average building worth is US$106,749, and average land parcel is valued at US$343,051. In terms of area, the largest lot area recorded was 557.2 m2 (5,977,860 ft2), and the average lot size was approximately 217 m2 (2,336 ft2).

Properties were built from 1901 to 2017, with only one record built in 1901 and rebuilt in 2017 (at the point of data analysis). Most buildings were built in the 1950s and 1960s (Figure 5), and most of the residential properties in the CMB were completed in the 1940s and 1950s. Initially, most residential buildings were located more inland and to the west; after the 1960s, building along the east coast commenced. According to 2017 property data, the current dollar value of the oldest CMB property (built in 1918) is US$378/ m2 (4,069 ft2). Properties built after 2014 have the highest average dollar/m2 (ft2) value and the eight highest average values are relatively new construc- tions. The highest recorded value is a penthouse at the W Hotel and Residences, Miami Beach, which sold in June 2017 for US$325.3/m2

(US$3,502/ft2), the highest in the entire United States on its date of sale (Rodriguez 2017). In gen- eral, Hurricane Andrew became an important benchmark for developing a new set of building standards to better protect structures, improve building codes, and build to higher standards with sturdier structures (Tsikoudakis 2012). Therefore, properties built prior to the 2002 building code are not built to the same standard, and this has a significant impact on real estate values. New codes call for shatterproof windows, fortified roofs, and reinforced concrete pillars, among other specifica- tions, and real estate agents and informed buyers put a premium on these features.

To assess the spatial patterns of property values across the CMB, we conducted Getis–Ord Gi* hot spot analysis. This technique helps identify areas of localized concentration or clustering across space (Getis and Ord 1992; Ord and Getis 1995). The Getis–Ord Gi* is a neighborhood-based statistic that identifies hot and cold spots by considering each property value within the context of all other prop- erty values in the neighborhood. Thus, it determines whether and how the local pattern of property val- ues in the neighborhood is statistically different from the global pattern of property values in the entire study area. The Gi* statistic as expressed is actually a z score: Statistically significant high Gi* values indicate clustering or the presence of hot or cold spots (Figure 6). The z scores compare prop- erty values across the CMB, showing areas where property is valued relatively high or low. Finally, the variations in the property values were examined in relation to the spatial patterns of vulnerability across the CMB. Based on the results of the analysis, which showed that the CMB had a high proportion of transient residents, we decided to interview three prominent real estate agents to probe opinions about their perceptions of this cohort’s awareness of and responsiveness to SLR.

Results

The exposure surface (Figure 3a) for the CMB scores areas of exposure on a scale of 1 (low) to 6.5 (high). High-exposure scores were concentrated along the east coast, with scattered areas in the cen- ter of the city. Most of the city is classified as a low- exposure area. The east coast of the city is most exposed to the ocean and associated with storm surges and the effects of SLR. This area is also very prone to beach erosion and has to be replenished periodically. It is lined with many high-rise residen- tial and hotel buildings originating from the 1960s. Lower elevation here also makes this area particu- larly exposed to inundation during higher than nor- mal tides.

The readiness surface (Figure 3b) scores ranged from low readiness (1.425) to high readiness (5.825). Areas of high readiness mostly align with the loca- tions of storm drains. Our analysis, however, showed most of the city classified as low readiness, with a small concentration of moderate readiness in the southern part of the city. The south side of the city might be more ready than the rest of the city partly due to its dense development and areas of high vul- nerability. In addition, the south, popularly known as South Beach, appears to be more prepared for SLR because of its dependence on tourist and visitor revenues. On the one hand, because this iconic art deco precinct is an important asset, maintenance of storm drains and other measures (e.g., creation of

Sea Level Rise in Miami Beach 285

new reefs) have been deemed very important in this vicinity. On the other hand, the overall low score of readiness throughout the remainder of the city makes the wider area especially vulnerable to the impacts of SLR. Readiness and exposure surfaces were combined to create a vulnerability surface for the city, which helps to illuminate the need for higher readiness scores across the city.

The vulnerability of the city was categorized into four zones, ranking from low vulnerability (Zone 4) to high vulnerability (Zone 1) using natural breaks (Figure 3c). The majority of the city was categorized as Zone 3 (low-moderate vulnerability), whereas Zone 1 makes up only 4 percent of the total area. The spatial patterns of vulnerability were similar to those observed in exposure patterns, with the lowest

Figure 6 Results of Getis–Ord Gi* hot spot analysis of residential property values for selected years: (a) 2009 and (b) 2017. The maps represent areas of comparatively high and low property values throughout the City of Miami Beach.

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vulnerability concentrated around stormwater drains throughout the city. To improve vulnerability scores, the CMB can evaluate exposure to incorpor- ate more readiness measures across the city. Thus, it is evident that most of the CMB has moderate to high vulnerability to the impacts of SLR. These effects need to be further assessed in terms of impacts on property values.

The spatial patterns of property value hot spots at the 99 percent confidence level for all years (2009–2017) were consistently clustered on the southwestern islands of the city as well as along the west and southeast coasts (Figure 6). These are areas where property values are comparatively higher, mainly due to the direct ocean views. Cold spots of 99 percent confidence were concentrated in the north and south areas of the city as well as along the east coast. These are areas where property values are comparatively lower. From 2009 to 2017, property values in the south of the city declined over time (Figures 6a and 6b). Property values in the center and along the northwestern tip of the city are mod- erately priced. Scattered hot spots with 99 percent confidence also developed along the southernmost tip and northeastern tip of the city.

Property values in Zone 1 had the highest aver- age dollar value for every roll year and approxi- mately twice the value of Zone 3, which had the lowest (Figure 7). Although the areas in Zone 1 mimic the cold spots for property values throughout the years, this zone also incorporates the southern islands of the city where property values are com- paratively higher. For the 2017 roll year, 37 percent of properties were in Zone 3 with an average dollar value per square foot of US$399, whereas only 3 percent of properties were in Zone 1 with an aver- age dollar value per square foot of US$600.

Importantly, the most vulnerable areas have the highest average dollar value per square foot.

Discussion

Although our results do not indicate an obvious relationship between property values and vulnerabil- ity, several factors affect our CMB results. First, high income levels are associated with many CMB residents. Properties with high values located on islands in the south of the city, such as Star Island and Fisher Island, are homes to the rich and famous, who arguably are not as economically vulnerable. Second, high rates of transiency among CMB resi- dents might lead to lesser importance accorded to long-term predictions of local SLR. There is consid- erable discrepancy between the average daily popu- lation of 200,000þ and the permanent residents’ base of 91,000 in 2015 (Pedraja-Castro 2016). Eleven percent of the daily population are snowbirds or seasonal residents, and the art deco residential core has some of the most transient population in the entire metro Miami area, with two thirds of peo- ple having arrived in the last five years, and most of this population are renters (Nijman 2011). Short- term horizons are very different from those horizons of homeowners and permanent residents, especially those holding long-term mortgages. Transient resi- dents are less committed to making the CMB their permanent home. Nijman (2007) highlighted these wealthy transients living in upper-income residential areas like Miami Beach as ethnically integrated but highly segregated in terms of class. Residing “away from the scene of common urban activity is a reflec- tion of their detachment from the city: cosmopoli- tans bring their wealth to Miami, but they do not

Figure 7 Relationship between vulnerability zones and residential property values throughout the City of Miami Beach for the years 2009 and 2011–2017. The year 2010 is excluded because of missing data.

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often contribute their citizenship” (182). Some of the more affluent transients have primary homes elsewhere. Aranda, Hughes, and Sabogal (2014) noted that this group pursues a strategy of coloca- tion, always keeping an eye on staying as well as exiting. Our interviews with prominent real estate agents indicated a perception that, at this moment in time, transients are less inclined to respond to the impact of vulnerability to SLR and its effects on the value of their residences, especially if they are in the rental market and operate on the basis of thinking no further than three years out (interviews, real estate agents, May 2018). Although the CMB is dedicated to the effort of raising awareness of SLR and vulnerability throughout the city, there still exists a disconnect across the broad community. This could be due to the transiency of some resi- dents, language barriers, a failure by the real estate industry to provide informed information, and vari- ous degrees of denial concerning the invading seas. Certainly, the politics of the Trump administration and of the Florida governor, Rick Scott, which deny climate change, mean that national and statewide leadership and coordination are presently absent. Holden (2018) counted twenty climate science skep- tics who serve as agency leaders and advisors in the Trump administration. At the national level, all references to climate change have been removed from White House Web sites (except those promis- ing to eliminate Obama’s climate policies), and in Tallahassee, Governor Scott ordered a ban in 2015 of phrases such as “climate change” and “global warming” (but not SLR) in government communi- cations, Web sites, and reports (Sherman 2015).

SLR represents a paradigmatic shift for the CMB. For almost 100 years, its development has been based on growth and boosterism of a tropical paradise to vacation at and live. The new norm of rising seas and increasing exposures to new vulner- abilities and adaptation has not yet been factored into a different kind of place making in the CMB.

Beginning of More Comprehensive Data Collection and Assessment

Compiling multiple data sets about adaptation and mitigation measures, we created a comprehensive analysis of vulnerability to SLR and related it to real estate development and market buoyancy. Certainly, our methodology could be refined by considering finer grained analysis of seawalls (public and private and incorporation, or not, of the latest frictionless technologies) and by examining the functionality of individual reefs, dunes, storm drains, building heights, and so on. Such data are not readily avail- able but can be collected, categorized, and mapped in the future. We hope that our analysis generates increased attention for more sophisticated spatial

modeling and assessment of more detailed local and neighborhood impacts of adaptation and mitigation initiatives. For these endeavors, we underscore again that elevation with regard to SLR is not the only important data point to be considered in relation to climate and urban futures.

On the basis of our preliminary investigation evaluating the impact of vulnerability to SLR and the associated impacts on property values through- out the CMB, we note these points:

1. Exposure is high along the east coast of the city and southern islands.

2. Readiness is low throughout the city. 3. The east coast and southern islands are most

vulnerable, encompassing beachfront proper- ties as well as the Venetian Islands and including the highest valued real estate.

4. Least vulnerability occurs along storm drains.

5. From 1940 until the late 1960s, the devel- opment of the CMB boomed, with homes mostly built inland, away from the coast. From 1970 to the present, most develop- ment occurred along the east coast. No discernible change in the spatial pattern for property values (2009–2017) is evident, and shoreline properties continue to be the highest valued real estate.

6. The mismatch of property values and vul- nerability throughout the CMB is attrib- uted to high income, transiency, and a lack of responsiveness to SLR from both residents and real estate professionals. A recent study of realtors revealed that 64 percent of buyers do not inquire about cli- mate change and SLR when purchasing property (Bendixen and Amandi International 2017). Real estate industry professionals’ (attorneys, developers, real estate agents, and some banks) nondisclo- sure of material facts and failure to oper- ate on the moral high ground raise additional ethical concerns that should be governed by a climate-sensitive legal regime (Rizzardi 2015). An absence of legal oversight puts many homeowners and communities at future risk. Even though the city has made concerted efforts to take action against SLR and its impacts, dissonance persists at many levels. Countervailing evidence can be gleaned from the research literature, including a tilt toward climate gentrification, with some new buyers focusing on higher ele- vation properties in Miami–Dade and other owners offloading properties at risk to SLR (Bernstein, Gustafson, and Lewis 2018; Keenan, Hill, and Gumber 2018),

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but their data do not fully capture SLR- associated change as more risk-tolerant purchasers are stepping up. For example, Bendixen and Amandi International’s (2017, 25) annual assessment of the resi- dential real estate market in Miami–Dade rated Miami Beach as the city’s “hottest area” to buy in 2017.

7. Real estate, municipal taxes, and city budgets for adaptation measures are inter- linked. For example, an intact real estate market maintains the tax base and the funds potentially available for adaptation measures. Thus, mitigating the effects of SLR and adopting purposeful actions are essential to maintain homeowners’ and investors’ confidence in real estate. It needs to be highlighted, however, that the CMB is characterized by a high degree of transience, part-time residents, and second-home residents, and real estate investors’ and renters’ future responses remain unpredictable. Transient groups are less embedded in the CMB than full- time residents and might be among the first to leave, potentially throwing the entire tax base and adaptation system out of kilter. �

Notes

1 A king tide occurs when the moon has the strongest pull on the oceans and the Gulf Stream slows, increasing the height of the high tide.

2 The Southeast Florida Regional Climate Change Compact joined Broward, Miami–Dade, Monroe, and Palm Beach counties in January 2010 to coordinate mitigation and adaptation efforts. The compact calls for counties to collaborate to develop legislative programs, to dedicate staff and resources, and to meet annually to mark progress and identify emerging issues. (www. southeastfloridaclimatecompact.org/who-we-are/; acc- essed June 10, 2017).

3 CMB’s Sustainability Plan (CMB 2015) is a living document encompassing its guiding principle, program areas, goals, indicators, targets, and initiatives.

4 Due to the localized nature of vulnerability, input from local policymakers and people knowledgeable about local conditions is essential to the construction of vulnerability indexes (Barnett et al. 2008; Frazier et al. 2013; Oulahen et al. 2017).

5 Vulnerability is defined differently by various scholars in terms of external and internal, biophysical, and socioeconomic aspects (F€ussel 2009). We employ an integrated approach incorporating both biophysical and socioeconomic indicators to calculate readiness and to determine vulnerability. The integrated approach provides important insights into the causes and consequences of vulnerability (Eakin and Luers 2006; F€ussel 2007). Moreover, indicator-based

vulnerability is very effective in synthesizing complex information into a score or metric and is highly applicable for policy decision making (Hinkel 2011; Chang et al. 2018).

ORCID

Richard Grant http://orcid.org/0000-0002- 5409-8117 Shouraseni Sen Roy http://orcid.org/0000-0003- 4158-7082

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ZELLA ANN CONYERS is a geographer who graduated with her master’s in geography in 2017 from the University of Miami, Coral Gables, FL 33146. E-mail: [email protected]. Her research interests are in wildlife management and sea level rise. Her recent works were on sea level rise in Miami and the invasion of the python throughout Florida.

RICHARD GRANT is a Professor at the University of Miami, Coral Gables, FL 33146. E-mail: [email protected]. He is a human geographer. His research interests are urban policies, the green economy, Miami, and cities in Africa, especially Accra, Cape Town, and Johannesburg. He currently is engaging in research projects on e-waste in Accra, the green economy in Cape Town, smart cities, and sea level rise in Miami.

SHOURASENI SEN ROY is a Professor at the University of Miami, Coral Gables, FL 33146. E-mail: [email protected]. Her research interests include spatial and temporal analyses of long-term trends in climate processes in the Global South. Recently she has been working on various research topics based in South Florida.

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