The Regional Impacts of Climate Change

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6.1. Regional Characteristics

The Latin American region spans a vast geographic and ecological range, from the subtropics of the Northern Hemisphere to the subpolar tip of the South American subcontinent; the region's largest portion lies in the tropical zone. The region consists of 20 independent states and the territory of French Guiana (an overseas department of France) (see Box 6-1 and Figure 6-1).

Figure 6-1: The Latin America region [compiled by the World Bank Environment Department Geographic Information System (GIS) Unit;].

The northern part of the region includes Mexico and the countries of the Central American isthmus, which are characterized by a broken relief of mountain ranges, tablelands or plateaus, shallow depressions, and numerous valleys-including desert (Baja California and Sonora) and semi-arid areas (Mexican highlands and coastal plains). South America is vertebrated by the Andean cordillera, a continuous mountain chain about 9,000 km long. The massive Andes host important glaciers and volcanoes, as well as a number of high plateaus. These high plateaus were the cradle of ancient civilizations and today host the region's largest rural population. This remarkable orographic barrier and the large oceans surrounding the subcontinent greatly influence the region's climate and land-use patterns. The lower eastern slopes of the Andes, together with the Guianas Highlands and the Brazilian Plateau, make up the habitats of the Colombia-Venezuela Llanos and the Amazon rainforest-the most important humid forest of the world.

Major biogeographical areas to the south of the Amazon forest include the woody Cerrado/Cerradinho and Chaco ecosystems and, further south, the Pampean region of Argentina. Extending southward from a latitude of 40�S, the Patagonian tableland-a region of vast steppe-like plains-rises westward from about 100 m on the coastline to about 1,000 m at the base of the Andes, with a surface area of about 670,000 km². Other important ecosystems in the region are the Yunga valleys in Bolivia and tropical/subtropical forests in Paraguay, Brazil, and Argentina. In recent decades, these forests have been subject to strong anthropogenic pressures to increase agricultural land area. For instance, only 4% of the tropical forest originally covering eastern Paraguay remained in the mid-1950s.

South America also has important coastal and inland wetlands with very high biodiversity; the combined biodiversity of these ecosystems and of Latin America's tropical, subtropical, and temperate ecosystems represents the world's largest genetic pool. Annex D of this report provides the number of known and endemic mammal, bird, and flowering plant species in each of the Latin American countries. The most important freshwater wetlands are those of El Pantanal (Brazil) and Iber� (Argentina). These wetlands are associated with the large international Rio de la Plata basin (embracing about 5.1 million km²), whose main component rivers-Paraguay, Paran�, and Uruguay-have a discharge of 79,400 m³/s. Integration with the Orinoco (70,000 m³/s) and Amazonas (180,000 m³/s) basins makes this area the largest running surface-water system in the world (329,400 m³/s), accounting for approximately 35% of global runoff and covering an area of about 12 million km². These very important river systems could be adversely affected by climate change and mismanagement of associated ecosystems, particularly further deforestation and, inter alia, deterioration of the buffer capacity of inland wetlands. The importance of the Amazon basin is depicted in Table 6-1. Table 6-2 provides the estimated deforestation rate of each country within this basin.

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