Latin America includes all continental countries of the Americas from Mexico to Chile and Argentina, as well as adjacent seas. The region is highly heterogeneous in terms of climate, ecosystems, human population distribution, and cultural traditions. Several Latin American countries-especially those of the Central American isthmus, Ecuador, Brazil, Peru, Bolivia, Chile, and Argentina-are significantly affected with adverse socio-economic consequences by seasonal to interannual climate variability, particularly the ENSO phenomenon. Most production is based on the region's extensive natural ecosystems, and the impacts of current climate variability on natural resources suggest that the impacts of projected climate changes could be important enough to be taken into account in national and regional planning initiatives. Land use is a major force driving ecosystem change at present, interacting with climate in complex ways. This factor makes the task of identifying common patterns of vulnerability to climate change very difficult.
Ecosystems: Large forest and rangeland areas are expected to be affected as a result of projected changes in climate, with mountain ecosystems and transitional zones between vegetation types extremely vulnerable. Climate change could add an additional stress to the adverse effects of continued deforestation in the Amazon rainforest. This impact could lead to biodiversity losses, reduce rainfall and runoff within and beyond the Amazon basin (reduced precipitation recycling through evapotranspiration), and affect the global carbon cycle.
Hydrology and Water Resources: Climate change could significantly affect the hydrological cycle, altering the intensity and temporal and spatial distribution of precipitation, surface runoff, and groundwater recharge, with various impacts on different natural ecosystems and human activities. Arid and semi-arid areas are particularly vulnerable to changes in water availability. Hydropower generation and grain and livestock production are particularly vulnerable to changes in water supply, particularly in Costa Rica, Panama, and the Andes piedmont, as well as adjacent areas in Chile and western Argentina between 25�S and 37�S. The impacts on water resources could be sufficient to lead to conflicts among users, regions, and countries.
Food and Fiber Production: Decreases in agricultural production -even after allowing for the positive effects of elevated CO2 on crop growth and moderate levels of adaptation at the farm level-are projected for several major crops in Mexico, countries of the Central American isthmus, Brazil, Chile, Argentina, and Uruguay. In addition, livestock production would decrease if temperate grasslands have to face substantial decreases in water availability. Extreme events (e.g., floods, droughts, frosts, storms) have the potential to adversely affect rangelands and agricultural production (e.g., banana crops in Central America). The livelihoods of traditional peoples, such as many Andean communities, would be threatened if the productivity or surface area of rangelands or traditional crops is reduced.
Coastal Systems: Losses of coastal land and biodiversity (including coral reefs, mangrove ecosystems, estuarine wetlands, and marine mammals and birds), damage to infrastructure, and saltwater intrusion resulting from sea-level rise could occur in low-lying coasts and estuaries in countries such as those of the Central American isthmus, Venezuela, Argentina, and Uruguay. Sea-level rise that blocks the runoff of flatland rivers into the ocean could increase the risks of floods in their basins (e.g., in the Argentine Pampas).
Human Settlements: Climate change would produce a number of direct and indirect effects on the welfare, health, and security of the inhabitants of Latin America. Direct impacts resulting from sea-level rise, adverse weather, and extreme climatic conditions (e.g., floods, flash floods, windstorms, landslides, and cold and heat outbreaks), as well as indirect effects through impacts on other sectors such as water and food supply, transportation, energy distribution, and sanitation services, could be exacerbated by projected climate change. Particularly vulnerable groups include those living in shanty towns in areas around large cities, especially where those settlements are established in flood-prone areas or on unstable hillsides.
Human Health: Projected changes in climate could increase the impacts of already serious chronic malnutrition and diseases for some Latin American populations. The geographical distributions of vector-borne diseases (e.g., malaria, dengue, Chagas') and infectious diseases (e.g., cholera) would expand southward and to higher elevations if temperature and precipitation increase. Pollution and high concentrations of ground-level ozone, exacerbated by increasing surface temperature, would have the potential to negatively affect human health and welfare, especially in urban areas.
Conclusions: Increasing environmental deterioration (e.g., changes in water availability, losses of agricultural lands, and flooding of coastal, riverine, and flatland areas) arising from climate variability, climate change, and land-use practices would aggravate socioeconomic and health problems, encourage migration of rural and coastal populations, and deepen national and international conflicts.
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