Glaciers in the high Andes and three major ice fields in southern South America represent the cryosphere in Latin America. Warming in high mountain regions could lead to disappearance of significant snow and ice surfaces. In addition, changes in atmospheric circulation resulting from the ENSO phenomenon and climate change could modify snowfall rateswith a direct effect on the seasonal renewal of water supplyand surface and underground runoff in piedmont areas. This could affect mountain sports and tourist activities, which represent an important source of income in some economies. Glaciers are melting at an accelerated rate in the Venezuelan (Schubert, 1992; Hastenrath and Ames, 1995) and Peruvian Andes.
In the humid tropics, extreme precipitation events would increase the number of reservoirs silting up well before their design lives have been reached. Other areas affected by the impact of climate change on water resources could be those that rely on freshwater ecosystems (i.e., lakes and inland wetlands and their biota), including commercial and subsistence fisheries.
According to climate change projections, approximately 70% of the current temperate forest in Mexico could be affected by climate change (Villers, 1995). Other vulnerability studies (Gay-García and Ruiz Suarez, 1996)carried out on the basis of Canadian Climate Centre (CCC)-J1 (Boer et al., 1992; McFarlane et al., 1992; Boer, 1993) and Geophysical Fluid Dynamics Laboratory (GFDL)-A3 (Wetherald and Manabe, 1988) GCMssuggest that 10% of all vegetation types in northern Mexico's ecosystemsincluding forests and shrublands of southern Chihuahua, eastern Coahuila, northern Zacatecas, and San Luis Potosìwould be affected by drier and warmer conditions, resulting in expansion of dry and very dry tropical forests and xerophytic shrublands.
Studies of vulnerability to sea-level rise (Perdomo et al., 1996) have suggested that countries such as Venezuela and Uruguay could suffer adverse impacts, leading to losses of coastal land and biodiversity, saltwater intrusion, and infrastructure damage. Impacts likely would be multiple and complex, with major economic implications. In Central America, impacts associated with sea-level rise would have their greatest effects on infrastructure, agriculture, and natural resources along the coastline, with immediate effects on socioeconomic conditions in the isthmus countries. Sea-level rise would exacerbate the processes of coastal erosion and salinization of aquifers and increase flooding risks and the impacts of severe storms along the coastline (Campos et al., 1997). Flooding associated with sea-level rise is one of the main impacts in lowland areas such as the Amazon, Orinoco, and Parana River deltas and the mouth of other rivers, such as the Magdalena in Colombia. The report also identified the Rio de La Plata estuary as an area where saltwater intrusion could create problems in the freshwater supply.
In Latin America's extremely arid deserts (<100 mm annual precipitation)the Chihuahuan, Sonoran, Peruvian, Atacama, Monte, and Patagoniathe impacts of climate change are not expected to be severe (Canziani et al., 1998), because these systems already are adapted to wide fluctuations in rainfall. Therefore, hyper-arid lands are not as susceptible as drylands to climate change (Middleton and Thomas, 1997).
Studies developed in Costa Rica and Nicaragua (Halpin et al., 1995) observed that shifts may occur in climatic zones that are associated with particular vegetation types in these countries. Global warming would have its greatest impacts on the cold temperate forest of southern Chile and Argentina, especially those neighboring xerophytic ecosystem types.
Projected changes in climate could increase the impacts of already serious chronic malnutrition and diseases affecting a large sector of the Latin American population. The geographical distribution of vector-borne diseases (e.g., malaria) would spread to higher elevations.
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