IPCC Fourth Assessment Report: Climate Change 2007
Climate Change 2007: Working Group II: Impacts, Adaptation and Vulnerability

13.4.4 Coasts

The majority of vulnerability and impacts assessments in Latin America have been made under the framework of National Communications (NC) to the UNFCCC (United Nations Framework Convention on Climate Change). Unfortunately the methodological approaches adopted are very diverse. Many are based on incremental scenarios (SLR 0.3-1.0 m), in some cases combined with coastal river flooding. Some include a cost-benefit analysis with and without measures (e.g., Ecuador, El Salvador and Costa Rica). Long-term and recent trends of SLR, flooding and storm surges are not always available or analysed. Some other countries (e.g., Chile and Peru) prioritise the impacts of ENSO events and the increase in SST on fisheries.

Significant impacts of projected climate change and sea-level rise are expected for 2050-2080 on the Latin American coastal areas. With most of their population, economic activities and infrastructure located at or near sea-level, coastal areas will be very likely to suffer floods and erosion, with high impacts on people, resources and economic activities (Grasses et al., 2000; Kokot, 2004; Barros, 2005; UCC, 2005). Results from several studies using SLR incremental and future climate change scenarios are summarised in Table 13.7. Projected impacts which would entail serious socio-economic consequences include floods; population displacement; salinisation of lowland areas affecting sources of drinking water (Ubitarán Moreira et al., 1999); coastal storm regime modification; increased erosion and altered coastal morphology (Conde, 2001; Schaeffer-Novelli et al., 2002; Codignotto, 2004; Villamizar, 2004); diversion of farm land; disruption of access to fishing grounds; negative impacts on biodiversity, including mangroves; salinisation and over-exploitation of water resources, including groundwater (FAO, 2006); and pollution and sea-water acidification in marine and coastal environments (Orr et al., 2005). Other factors such as the artificial opening of littoral bars, pressures from tourism, excessive afforestation with foreign species, and coastal setback starting from the decrease of the fluvial discharge in the Patagonian rivers, will add to the impacts on coastal environments (Grasses et al., 2000; Rodríguez-Acevedo, 2001; OAS-CIDI, 2003; Kokot, 2004).

Table 13.7. Future impacts and vulnerability to climate change and variability in Latin America: people and coastal systems.

Country/Region Climate scenario Impacts/costs (people, infrastructure, ecosystems, sectors) 
Latin America HADCM3: SRES B2, B1, A2, A1FI. SLR (Nicholls, 2004) Assuming uniform population growth, no increase in storm intensity and no adaptation response (constant protection) the average annual number of coastal flood victims by the 2080s will probably range between 3 million and 1 million under scenarios A and B, respectively. If coastal defences are upgraded in line with rising wealth (evolving adaptation), the number of victims would be 1 million people under the worst-case scenario (A1FI). Finally, if coastal defences are upgraded against sea-level rise (enhanced adaptation); no people should be affected (Warren et al., 2006). People at risk1 on coastal flood plains are likely to increase from 9 million in 1990 to 16 million (B1) and 36 million (A2) by the 2080s. 
Low-lying coasts in Brazil, Ecuador, Colombia, Guyana, El Salvador, Venezuela  SRES A2: 38-104 cm Mangrove areas could disappear from more exposed and marginal environments and, at the same time, the greatest development would occur in the more optimal high-sedimentation, high-tide and drowned river-valley environments. Shrimp production will be affected, with a consequent drop in production and GDP share (Medina et al., 2001). 
El Salvador SLR: 13-110 cm Land loss ranging from 10% to 27.6% of the total area (141-400.7 km2) (NC-El Salvador, 2000). 
Guyana  SLR 100 cm projected by GCMs Over 90% of the population and the most important economic activities are located in coastal areas which are expected to retreat by as much as 2.5 km (NC-Guyana, 2002). 
Mesoamerican coral reef and mangroves from Gulf of Mexico Warmer SST: 1-3°C by the 2080s under IPCC SRES scenarios Coral reef and mangroves are expected to be threatened, with consequences for a number of endangered species: e.g., the green, hawksbill and loggerhead turtles, the West Indian manatee, and the American and Motelet’s species of crocodile (Cahoon and Hensel, 2002). 
Costa Rica, Punta Arenas coast SLR 0.3-1.0 m Sea water could penetrate 150 to 500 m inland, affecting 60-90% of urban areas (NC-Costa Rica, 2000). 
Ecuador, Guayas river system, associated coastal zone and Guayaquil City No-change: LANM0, moderate: LANM1, and severe changes: LANM2, with and without economic development Losses of US$1,305 billion, which include shrimp cultures, mangroves, urban and recreation areas, supply of drinking water, as well as banana, rice and sugarcane cultivation. US$1,040 billion would be under risk. Evacuated and at-risk population should rise to 327,000 and 200,000 people, respectively. Of the current 1,214 km2 of mangroves, it is estimated that 44% will be affected by the LANM2 scenario (NC-Ecuador, 2000). 
Peru Intensification of ENSO events and increases in SST. Potential SLR Increased wind stress, hypoxia and deepening of the thermocline will impact on the marine ecosystem and fisheries, i.e., reduction of spawning areas and fish catches of anchovy. Flooding of infrastructure, houses and fisheries will cause damage valued at US$168.3 million. Global losses on eight coastal regions in Peru are estimated at US$1,000 million (NC-Perú, 2001). 
Colombia SLR 1.0 m Permanent flooding of 4,900 km2 of low-lying coast. About 1.4 million people would be affected; 29% of homes would be highly vulnerable; the agricultural sector would be exposed to flooding (e.g., 7.2 Mha of crops and pasture would be lost); 44.8% of the coastal road network would be highly vulnerable (NC-Colombia, 2001). 
Argentina (Buenos Aires City) Storm surges and SLR 2070/2080 Very low-lying areas which are likely to be permanently flooded are now only thinly populated. Vulnerability is mostly conditioned by future exposure to extreme surges. Rapid erosion with its consequent coastline retreat will occur at a rate depending on geological characteristics of the area. As a result of adaptation to present storm-surge conditions, the social impact of future permanent flooding will be relatively small (Kokot, 2004; Kokot et al., 2004; Menéndez and Ré, 2005). 
Argentina and Uruguay (western Montevideo) coastal areas. Buenos Aires and Rio Negro Provinces SLR, climate variability, ENSO, storm surges (‘sudestadas’) Increases in non-eustatic factors (i.e., an increase in ‘sudestadas’ (a strong south-eastern wind along the Rio de la Plata coast) and freshwater flow, the latter often associated with El Niño, would accelerate SLR in the Río de la Plata, having diverse environmental and societal impacts on both the Argentine and Uruguay coasts over the next few decades, i.e., coastal erosion and inundation. Low-lying areas (estuarine wetlands and sandy beaches very rich in biodiversity) will be highly vulnerable to SLR and storm surges (southern winds). Loss of land would have a major impact on the tourism industry, which accounts for 3.8% of Uruguay’s GDP (Barros, 2003; Codignotto, 2004; Kokot, 2004, Kokot et al., 2004; NC-Uruguay, 2004; Nagy et al., 2005, 2006c; Natenzon et al., 2005b). 

1 This is defined as living below the 1 in 1,000 year flood level.

As for coastal tourism, the most impacted countries will be those where the sectoral contribution to the GDP, balance of payments and employment is relatively high, and which are threatened by windstorms and projected sea-level rise: such as those of Central America, the Caribbean coast of South America and Uruguay (Nagy et al., 2006a, c). Thus, climate change is very likely to be a major challenge for all coastal nations.