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(1) according to Arnell (2004, Table 7); (2) according to Arnell (2004, Tables 11 and 12).

demand (related to mean monthly runoff) in year 2010 with the scenario of +2°C and -15% precipitation (Caceres, 2004). In Chile, recent studies confirm the potential damage to water supply and sanitation services in coastal cities, as well as groundwater contamination by saline intrusion. In the Central region river basins, changes in streamflows would require many water regulation works to be redesigned (NC-Chile, 1999).

Under severe dry conditions, inappropriate agricultural practices (deforestation, soil erosion and the excessive use of agrochemicals) will deteriorate surface and groundwater quantity and quality. That would be the case in areas that are currently degraded, such as Leon, Sebaco Valley, Matagalpa and Jinoteca in Nicaragua, metropolitan and rural areas of Costa Rica, Central Valley rivers in Central America, the Magdalena river in Colombia, the Rapel river basin in Chile, and the Uruguay river in Brazil, Uruguay and Argentina (UNEP, 2003b).

Landslides are generated by intense/persistent precipitation events and rainstorms. Furthermore, in Latin America they are associated with deforestation and a lack of land planning and disaster-warning systems. Many cities of Latin America, which are already vulnerable to landslides and mudflows, are very likely to suffer the exacerbation of extreme events, with increasing risks/hazards for local populations (Fay et al., 2003). Accelerated urban growth, increasing poverty and low investment in water supply will contribute to: water shortages in many cities, high percentages of the urban population without access to sanitation services, an absence of treatment plants, high groundwater pollution, lack of urban drainage systems, storm sewers used for domestic waste disposal, the occupation of flood valleys during drought seasons, and high impacts during flood seasons (Tucci, 2001).

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 (Ubitaran 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; Rodriguez-Acevedo, 2001; OAS-CIDI, 2003; Kokot, 2004).

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.

13.4.5 Human health

The regional assessments of health impacts due to climate change in the Americas show that the main concerns are heat stress, malaria, dengue, cholera and other water-borne diseases (Githeko and Woodward, 2003). Malaria continues to pose a serious health risk in Latin America, where 262 million people (31% of the population) live in tropical and sub-tropical regions with some potential risk of transmission, ranging from 9% in Argentina to 100% in El Salvador (PAHO, 2003). Based on SRES emissions scenarios and socio-economic scenarios, some projections indicate decreases in the length of the transmission season of malaria in many areas where reductions in precipitation are projected, such as the Amazon and Central America. The results report additional numbers of people at risk in areas around the southern limit of the disease distribution in South America (van Lieshout et al., 2004). Nicaragua and Bolivia have predicted a possible increase in the incidence of malaria in 2010, reporting seasonal variations (Aparicio, 2000; NC-Nicaragua, 2001). The increase in malaria and population at risk could impact the costs of health services, including treatment and social security payments.

Kovats et al. (2005) have estimated relative risks (the ratio of risk of disease/outcome or death among the exposed to the risk among the unexposed) of different health outcomes in the year 2030 in Central America and South America, with the highest relative risks being for coastal flood deaths (drowning), followed by diarrhoea, malaria and dengue. Other models project a substantial increase in the number of people at risk of dengue due to changes in the geographical limits of transmission in Mexico, Brazil, Peru and Ecuador (Hales et al., 2002). Some models project changes in the spatial distribution (dispersion) of the cutaneous leishmaniasis vector in Peru, Brazil, Paraguay, Uruguay, Argentina and Bolivia (Aparicio, 2000; Peterson and Shaw, 2003), as well as the monthly distribution of dengue vector (Peterson et al., 2005).

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

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).

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-Peru, 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 Storm surges and SLR Aires City) 2070/2080

Argentina (Buenos Storm surges and SLR Aires City) 2070/2080

Argentina and Uruguay (western Montevideo) coastal areas. Buenos Aires and Rio Negro Provinces

SLR, climate variability, ENSO, storm surges ('sudestadas')

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).

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.

Climate change is likely to increase the risk of forest fires. In some countries, wildfires and intentional forest fires have been associated with an increased risk of out-patient visits to hospital for respiratory diseases and an increased risk of breathing problems (WHO, 2000; Mielnicki et al., 2005). In urban areas exposed to the 'heat island' effect and located in the vicinity of topographical features which encourage stagnant air mass conditions and the ensuing air pollution, health problems would be exacerbated, particularly those resulting from surface ozone concentrations (PAHO, 2005). Furthermore, urban settlements located on hilly ground, where soil texture is loose, would be affected by landslides and mudflows; thus people living in poor-quality housing would be highly vulnerable.

Highly unusual stratospheric ozone loss and UV-B increases have occurred in the Punta Arenas (Chile) area over the past two decades, resulting in the non-photoadapted population being repeatedly exposed to an altered solar UV spectrum causing a greater risk of erythema and photocarcinogenesis. According to Abarca and Cassiccia (2002), the rate of non-melanoma skin cancer, 81% of the total, has increased from 5.43 to 7.94 per 100,000 (46%).

Human migration resulting from drought, environmental degradation and economic reasons may spread disease in unexpected ways, and new breeding sites for vectors may arise due to increasing poverty in urban areas and deforestation and environmental degradation in rural areas (Sims and Reid, 2006).

Recent studies warn of the possible re-emergence of Chagas' disease in Venezuela (Feliciangeli et al., 2003; Ramirez et al., 2005) and Argentina (PNC, 2005), and a wider vector distribution in Peru (Caceres et al., 2002). Some models project a dispersal potential for Chagas' vector species into new areas (Costa et al., 2002).

A national assessment of Brazilian regions demonstrated that the north-east is the most vulnerable to the health effects of changing climate due to its poor social indicators, the high level of endemic infectious diseases, and the periodic droughts that affect this semi-arid region (Confalonieri et al., 2005).

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