13.2.3 Non-climatic stresses
Effects of demographic pressure
Migration to urban areas in the region exceeds absorption capacity, resulting in widespread unemployment, overcrowding, and the spread of infectious diseases including HIV/AIDS, due to lack of adequate infrastructure and urban planning (UNEP, 2003b). Latin America is the most urbanised region in the developing world (75% of its population). The most urbanised countries are Argentina, Brazil, Chile, Uruguay and Venezuela, while the least urbanised are Guatemala and Honduras (UNCHS, 2001). As a consequence, the regional population faces both traditional (infectious and transmissible diseases) and modern risks (chronic and degenerative diseases) in addition to those related to urban landslides and floods. Modern risks result from urbanisation and industrialisation, while poor and rural populations still suffer from ‘traditional risks’. There is a significant problem of urban poverty in areas where malnutrition, poor water quality and a lack of sewage/sanitary services and education prevail. However, the line between urban and rural in many parts of the region is becoming increasingly blurred, particularly around large urban areas.
A strong reduction in employment rates, with the associated downgrading of the social situation, observed in Latin America in the 1990s (poverty affecting 48.3% and extreme poverty 22.5% of the population), has generated large-scale migration to urban areas. Although this migration trend continues, the Economic Commission for Latin America and the Caribbean (ECLAC) reports that, in spite of the fact that the region is on track to meet the Millenium Development Goals’ (MDGs) extreme poverty goal (to halve the number of people living on less than $1/day by 2015), the year 2006 would show a reduction to 38.5% and 14.7% of the above poverty indices (La Nación, 2006).
Over-exploitation of natural resources
It is well established that over-exploitation is a threat to 34 out of 51 local production systems of particular importance to artisanal fishing along the coastal waters in Latin America (UNEP, 2003b; FAO, 2006) and has caused the destruction of habitats such as mangroves, estuaries and salt marshes in Central America and Mexico (Cocos in Costa Rica, Tortuguero-Miskitos Islands in Nicaragua and the Gulf of Mexico in Mexico) (Mahon, 2002; NOAA/OAR, 2004).
Urbanisation (without a land planning or legal framework in most of the countries), large aquaculture developments, the expansion of ecotourism and the oil industry, the accidental capture of ecologically important species, the introduction of exotic species, land-based sources of coastal and marine pollution, the depletion of coral reefs and the mismanagement of water resources impose increasing environmental pressures on natural resources (Young, 2001; Viddi and Ribeiro, 2004).
The rapidly expanding tourism industry is driving much of the transformation of natural coastal areas, paving the way for resorts, marinas and golf courses (WWF, 2004). Aquifer over-exploitation and mismanagement of irrigation systems are causing severe environmental problems; e.g., salinisation of soil and water in Argentina (where more than 500,000 ha of the phreatic (i.e., permanently-saturated) aquifer shows high levels of salinity and nitrates) (IRDB, 2000) and sanitation problems in a great number of cities such as Mexico City, San José de Costa Rica, and Trelew, Río Cuarto and La Plata in Argentina. In Belize City, a system of mangrove-lined ponds and mangrove-wetland drainage areas has served as a natural sewage treatment facility for much of the city’s waste water. Recently, dredging for a massive port expansion has resulted in the destruction of more mangroves and the free ecosystem services they provided (WWF, 2004).
Pollution of natural resources, such as natural arsenic contamination of freshwater, affects almost 2 million people in Argentina, 450,000 in Chile, 400,000 in Mexico, 250,000 in Peru and 20,000 in Bolivia (Canziani, 2003; Pearce, 2003; Clark and King, 2004). Another insidious contamination widespread in the region is produced by fluorine. In the Puyango river basin (Ecuador), suspended sediments and metal contamination increase significantly during ENSO events (Tarras-Wahlberg and Lane, 2003). In the upper Pilcomayo basin, south-east Bolivia, pollution by heavy metals from mining operations in Potosí affects the migration and fishing of sábalo (Prochilodus lineatus), which is a very important source of income in the region (Smolders et al., 2002). As a result of the Salado del Norte (Argentina) river flood of 2003 (which covered more than one-third of the urban district), 60,000 tonnes of solid waste were disseminated all over the city of Santa Fe; 135 cases of hepatitis, 116 of leptospirosis and 5,000 of lung disease were officially reported as a result (Bordón, 2003).
Air pollution due to the burning of fossil fuels is a problem that affects many cities of Latin America. Transport is the main contributor (e.g., in Mexico City, Santiago de Chile and São Paulo). Thermoelectric energy generation is the second primary source of air pollution in Lima, Quito and La Paz (PAHO, 2005). Climate and geography play a significant role in this situation; e.g., the occurrence of thermal inversions, such as in Mexico City, Lima and Santiago de Chile. In Mexico City, surface ozone has been linked to increased hospital admissions for lower respiratory infections and asthma in children (Romieu et al., 1996). Regarding exposure effects to biomass particles, Cardoso de Mendonça et al. (2004) have estimated that the economic costs of fire in the Amazon affecting human health increased from US$3.4 million in 1996 to US$10.7 million in 1999.