Eric Harmsen, Department of Agricultural and Biosystems Engineering, University of Puerto Rico
Azad Henareh Khalyani, Natural Resource Ecology Laboratory, Colorado State University
Eva Holupchinski, USDA Forest Service International Institute of Tropical Forestry
James P. Kossin, National Oceanic and Atmospheric Administration
Amanda J. Leinberger, Center for Climate Adaptation Science and Solutions, University of Arizona
Vanessa I. Marrero-Santiago, Department of Natural and Environmental Resources, Coastal Zone Management Program
Odalys Martínez-Sánchez, NOAA National Weather Service
Kathleen McGinley, USDA Forest Service International Institute of Tropical Forestry
Melissa Meléndez Oyola, University of New Hampshire
Pablo Méndez-Lázaro, University of Puerto Rico
Julio Morrell, University of Puerto Rico
Isabel K. Parés-Ramos, USDA Forest Service International Institute of Tropical Forestry
Roger Pulwarty, National Oceanic and Atmospheric Administration
William V. Sweet, NOAA National Ocean Service
Adam Terando, U.S. Geological Survey, Southeast Climate Adaptation Science Center
Sigfredo Torres-González, U.S. Geological Survey (Retired)
Jess K. Zimmerman, University of Puerto Rico
Mariano Argüelles, Puerto Rico Department of Agriculture
Gabriela Bernal-Vega, University of Puerto Rico
Roberto Moyano, Estudios Técnicos Inc.
Pedro Nieves, USVI Coastal Zone Management
Aurelio Mercado-Irizarry, University of Puerto Rico
Dominique Davíd-Chavez, Colorado State University
Rey Rodríguez, Puerto Rico Department of Agriculture
Allyza Lustig, Program Coordinator
Apurva Dave, International Coordinator and Senior Analyst
Christopher W. Avery, Senior Manager
<b>Gould, W.A., E.L. Díaz, (co-leads),</b> N.L. Álvarez-Berríos, F. Aponte-González, W. Archibald, J.H. Bowden, L. Carrubba, W. Crespo, S.J. Fain, G. González, A. Goulbourne, E. Harmsen, E. Holupchinski, A.H. Khalyani, J. Kossin, A.J. Leinberger, V.I. Marrero-Santiago, O. Martínez-Sánchez, K. McGinley, P. Méndez-Lázaro, J. Morell, M.M. Oyola, I.K. Parés-Ramos, R. Pulwarty, W.V. Sweet, A. Terando, and S. Torres-González, 2018: U.S. Caribbean. In <i>Impacts, Risks, and Adaptation in the United States: Fourth National Climate Assessment, Volume II</i> [Reidmiller, D.R., C.W. Avery, D.R. Easterling, K.E. Kunkel, K.L.M. Lewis, T.K. Maycock, and B.C. Stewart (eds.)]. U.S. Global Change Research Program, Washington, DC, USA, pp. 809–871. doi: 10.7930/NCA4.2018.CH20
Coasts are a central feature of Caribbean island communities. Coastal zones dominate island economies and are home to critical infrastructure, public and private property, cultural heritage, and natural ecological systems. Sea level rise, combined with stronger wave action and higher storm surges, will worsen coastal flooding and increase coastal erosion, likely leading to diminished beach area, loss of storm surge barriers, decreased tourism, and negative effects on livelihoods and well-being. Adaptive planning and nature-based strategies, combined with active community participation and traditional knowledge, are beginning to be deployed to reduce the risks of a changing climate.
Linkage Between Climate Change and Regional Risks
A high concentration of population and critical infrastructure in low-lying coastal areas increases vulnerability to sea level rise and storm surge and magnifies the effects of coastal flooding and beach erosion. For example, most of the population in Puerto Rico (62%, or more than 2.2 million) lives in the 44 coastal municipalities, where a total of 1,019,300 housing units are also located.83,84 It is also estimated that 401,145 people (11.5% of Puerto Rico’s total population) live in areas subject to inundation, and 56,114 people live in areas susceptible to storm surge, also known as the coastal high hazard areas.83 As sea level rises, storm surge and high energy wave action may cause shorelines to recede inland.85 Approximately 60% of 3,808 beach transects studied along the coasts of Puerto Rico (799 miles) experienced erosion from the 1970s to 2010. Of those transects, 5% suffered very high erosion, with a beach loss of 3.97 feet to 6.56 feet per year.86 Major loss of sand was identified in various municipalities of the north coast, including San Juan—the capital city and a center of economic activity, ports, and tourism—as well as Loíza and Dorado, which are cultural and tourist destinations. (For more information on effects from extremes and disaster events, see Key Message 5.)
The response of coastal systems to sea level rise is dependent on local natural and human factors.87 Natural ecological systems can protect coastlines from erosion but can also be affected by sea level rise and other environmental changes. Coral reefs, mangroves, and sand dunes buffer coastlines from erosion and inundation, providing protective services. They reduce risk to people and infrastructure from wave damage and flooding. The coral reef–mangrove systems can reduce risk and provide fishery services if space is available for landward mangrove migration; however, this process can be hampered by coastal development. Beaches and coastal dunes provide wave energy dissipation and coastal asset protection yet are highly susceptible to wave action and erosion.
The U.S. Caribbean Economy
The U.S. Caribbean territories of Puerto Rico and the U.S. Virgin Islands have distinct differences in topography, language, population size, governance, natural and human resources, and economic capacity. However, both are highly dependent on natural and built coastal assets. Service-related industries account for more than 60% of the USVI’s economy and cater to more than 570,000 tourists, as well as an additional 2.1 million cruise ship passengers who arrive to the island each year.88 In 2013 in the USVI, tourists and cruise ship passengers spent $851 million and $381 million, respectively (in 2013 dollars; $877 and $392 million, respectively, in 2015 dollars). Approximately 3.7 million people visited Puerto Rico in 2016 as tourists, and an additional 1.3 million people arrived via cruise ships. Tourist and cruise ship passenger expenditures amounted to $3.8 billion and $202 million, respectively (in 2016 dollars; $3.8 billion and $200 million, respectively, in 2015 dollars).89
Beaches, affected by sea level rise and erosion, are among the main tourist attractions; consequently, these revenues from tourism are at risk due to limitations of access and deterioration to the coastal landscape. In addition, residents’ recreational activities will likely be disrupted, as about 63% of Puerto Rican residents enjoy recreational activities such as swimming, bathing, or sunbathing on the beach.90
Critical Infrastructure at Risk, San Juan Metro Area
Figure 20.12: Puerto Rico’s Luis Muñoz Marín (LMM) international airport is already at risk from extreme weather …
Operations of Puerto Rico’s ports, the Luis Muñoz Marín (LMM) international airport, and the city of San Juan are currently at risk from extreme weather and climate-related events and will likely be even more vulnerable under projected sea level rise scenarios (Figure 20.12). In 2016, 93% of all passengers entering Puerto Rico through airports did so through the LMM airport.91 The U.S. Caribbean’s economy is also tied to climate impacts on Florida ports, as raw material for industries, food, clothes, and essential goods are shipped from Jacksonville, Florida, to the San Juan port and Isla Verde airport. As such, Florida’s infrastructure vulnerability also affects the U.S. Caribbean.
Cultural and historic sites in the U.S. Caribbean region are threatened by sea level rise and storm surge. In the USVI, two significant early prehistoric sites, the Aklis and Great Pond archaeological sites, are directly threatened by sea level rise.92 In Puerto Rico, effects on cultural heritage resources at risk due to climate change include impaired access to coastal resources like fishing, degraded ecotourism attractions, and loss of public access to beaches.93 One of Puerto Rico’s most notable cultural sites, the San Juan National Historic Site (El Morro), faces challenges from climate change, including sea level rise and coastal erosion.94
Critical Infrastructure, Property, and Real Estate
Sea level rise will likely increase threats to private, commercial, and residential property, as well as associated service infrastructure. Over 8,000 structures in Puerto Rico’s low-lying areas would be affected by an increase in sea level of 1.6 feet (0.5 m). A sea level increase of 6.5 feet (2 m) would affect more than 50,000 structures located along the coast, causing approximately $11.8 billion in losses (in 2017 dollars).83
Critical infrastructure in the region is vulnerable to the effects of sea level rise, storm surge, and flooding. As an example, if sea levels rise 6.5 feet (2 m), which could occur during this century under the Intermediate-High to Extreme scenarios,38,95 Puerto Rico and the USVI are projected to lose 3.6% and 4.6% of total coastal land area, respectively. Were such a rise to take place, Puerto Rico’s critical infrastructure near the coast would be negatively impacted, including drinking water pipelines and pump stations, sanitary pipelines and pump stations, one wastewater treatment plant, and six power plants and associated substations.96 In the USVI, infrastructure and historical buildings in the inundation zone for sea level rise include the power plants on both St. Thomas and St. Croix; schools; housing communities; the towns of Charlotte Amalie, Christiansted, and Frederiksted; and pipelines for water and sewage.
Challenges, Opportunities, and Success Stories for Reducing Risk
In Puerto Rico, the Department of Natural and Environmental Resources (DNER) commissioned the development of five climate change community-based adaptation plans for selected coastal municipalities.97 Through an active community participation process, which included surveys and participatory mapping, these plans evaluated the risks and vulnerabilities posed by climate change and developed recommendations and adaptation strategies that will serve as guidance for municipal governments, communities, and local businesses (Figure 20.13).97
Assessing Vulnerability with Communities
Figure 20.13: Culebra’s Mayor and community members worked on the participatory maps to identify risks, important …
The USVI has released a guidance document to promote resilient coastal and marine communities through Ecosystem-based Adaptation (EbA). EbA reduces risk through the protection and restoration of natural areas like mangroves, dunes, and wetlands. High-risk areas were identified through analysis of social vulnerability, risk exposure, and adaptive capacity. Eleven areas throughout the USVI were selected as optimal to implement EbA options, as they faced high-risk exposure, high sensitivity, and low adaptive capacity. When considering climate effects and adaptation in the Caribbean, traditional knowledge from those members of the community maintaining the most intimate relationships with the land and natural systems is key to the early stages of the planning process. Traditional fishing, subsistence agriculture, and plant harvesting practices may provide a better understanding of how Caribbean Indigenous knowledge systems have sustained generations in the past and can benefit future generations.98
Natural and nature-based shoreline responses are used as stabilization techniques against erosion and can provide habitat for coastal species. Wetlands, dunes, and mangroves experience less damage from severe storms and are more resilient than hardened shorelines, and they also provide multiple benefits such as habitat for fish and other living organisms, as well as support recreational and commercial activities.88 Mangroves alone can help reduce wave energy, erosion, and damage caused by large storms.99 The U.S. Fish and Wildlife Service and the Puerto Rico DNER have funded wetland and dune restoration projects at various sites along the coast of Puerto Rico as nonstructural solutions to reduce coastal flooding and beach erosion.
Adaptive planning and nature-based strategies are gaining increased attention in Puerto Rico, as they are more accessible to coastal communities and can be cost effective. Also, stabilization and excavation of vulnerable cultural sites throughout the USVI can serve to protect or salvage cultural resources from the effects of climate change.92