The Latin American population will increase to 838 million by the year 2050. Annual population growth rates will decrease from 1.68%, in the period 1995-2000, to an estimated 0.51% in the period 2040-2050, according to the medium prospect of the United Nations (Nawata, 1999). This signifies that the population explosion will continue, even if a decerease in population growth rates were possible. One of the critical difficulties caused by growing population is the problem of nutrition and availability of food. Global food supply is expected to meet the overall needs of the growing world population, but significant regional variation in crop yields as a result of climate change (Rosenzweig et al., 1993) could lead to an increased risk of hunger for an additional 50 million people by the year 2050. Because most Latin American countries' economies depend on agricultural productivity, the issue of regional variation in crop yields is very relevant for the region.

The area of the Latin American region is approximately 19.93 million km²—double that of Europe, but smaller than that of North America, Asia, or Africa. Latin America includes all of the continental countries of the Americas, from Mexico to Chile and Argentina, as well as adjacent seas (Canziani et al., 1998). Even though the region has a predominantly southern location, Latin America also has a presence in the northern hemisphere, including Mexico, Central America, the Guyanas, Suriname, Venezuela, and parts of Colombia, Ecuador, and Brazil.

Latin America's orographical systems present a predominant north-south orientation, extending from the ranges of Mexico and Central America to the southern Andes. These features divide the region into two contrasting but interdependent geosystems, influencing the climatic and hydrological patterns and making primary productivity a direct dependent variable of the aforementioned environmental factors (Lieth, 1976).

These conditions initially led to a prevalence of agricultural activities near coastlines. From the end of the 19th century and the arrival of European migrations, these activities were extended to inner valleys and plateaus. Pre-Colombian cultures, however, had developed many of their community farming activities in the high plateaus, where the largest proportion of Latin America indigenous communities still are settled.

Mountain ranges and high plateaus play an important role in determining local climates that are conditioned by altitude and orientation, which in turn enhance biological diversity. Agricultural diversification also is coupled to habitat heterogeneity through varying crop species and agricultural time schedules. Morello (1976) has reported the way in which hunting, fishing, cattle and sheep grazing, and cropping activities are correlated to discontinued habitats along the altitudinal gradients in the humid tropical Andes in Colombia. Similar patterns have been reported for the Andes of Ecuador (Cornik and Kirby, 1981). Mountain ranges in Latin America also should be considered genetic/germoplasm banks for a wide variety of plants cultivated since the pre-Hispanic period, as well as for domesticated animals (llama, alpaca) and their wild relatives. The success of agriculture in the Andes is based on the genetic variability of plant populations and on the people themselves who have acquired the proper technology after centuries of agricultural practices. This genetic variability has resulted not only in a high number of cultivated species but also in a striking diversity of cultivars and genotypes adapted to the environmental heterogeneity of the mountain ecosystems (Blanco Galdós, 1981).

Each valley or mountain range has its own characteristics, especially in the tropical Andes, making the area one of the most diverse physical and biological mosaics in the world. At the same time, local populations in the Andes have developed appropriate technologies that are applicable in highlands agriculture; these technological reservoirs are comparable only to those existing in the high plateaus of Asia (Morello, 1984)

Earthquakes, volcanoes, and tectonic movements are common all over Latin America. Some of these events may be catastrophic because urban and rural settlements are likely to be devastated, but some may have positive effects. For example, floods in Argentina, which originate in the high Andean watersheds, have devastating effects on cultivated valleys. However, aquifers previously exhausted through alfalfa irrigation become recharged, and salinized soils are washed. Furthermore, volcanic eruption generates soil enrichment, which nourishes a wide range of crops, including coffee in Central America and Colombia.

Latin America contains a large variety of climates as a result of its geographical configuration. The climatic spectrum ranges from cold, icy high elevations, with some of the few glaciers still found in the tropics, to temperate and tropical climate. The region also has large arid and semi-arid areas. One of the most important characteristics of Latin America from the climatic point of view is its large sensitivity and vulnerability to ENSO events. From northern Mexico to Tierra del Fuego, every country in the continent exhibits anomalous conditions associated with ENSO.

The region also hosts the largest pluvial forest in the world: 7.5 million km² constitute Amazonia, of which 6.12 million km² are within the Amazon basin. The average rainfall in the Amazon basin is about 2,300 mm yr-¹, with real evaporation estimated at 1,146-1,260 mm yr-¹. The Amazon is undoubtedly the world's largest river in terms of its outflow, with an average annual flow rate of 209,000 m³ sec^-1. The Amazon, the Parana-Plata, and the Orinoco carry into the Atlantic Ocean more than 30% of the freshwater of the world. However, these water resources are poorly distributed, and extensive zones have extremely limited water resources.

Latin America hosts one of the largest terrestrial and marine biological diversities in the world. South America has the largest fish catch on the eastern Pacific. There is an important flow of krill and other plankton species as a result of cold sea currents on both sides of the southern tip of South America. A combination of the prevailing atmospheric and oceanic circulation defines the climate and the land and sea productivity of the region. This explains the actual distribution of human settlements and the availability of basic services (e.g., water supply).

Overall, the health profile of the Latin American population can be classified as undergoing a slow epidemiological transition. At one extreme of the spectrum there is a high incidence of (and mortality from) chronic noninfectious diseases such as cardiovascular problems and cancer, which predominate in large metropolitan areas. On the other hand, infectious diseases still impose a heavy burden on the poverty-stricken parts of the population. The reasons for this dichotomy are two-fold: uneven socioeconomic development within countries and the extreme diversity of regional environments.

Latin America (and the Caribbean) has the greatest disparity in income distribution in the world. A mere 5% of the population receives 25% of all national income, and the top 10% receive 40%. Such proportions are comparable only to those found in some African countries (IDB, 1999).

Many problems that have affected Latin America adversely are now showing a wood-saw type of change, with some temporary improvements and downfalls. However, in some countries of the region, improvement in the macroeconomy is being observed, in spite of the negative impact from recent developments in Asia and some countries of the region (Mexico and Brazil). Improvement currently observed in the economies of Mexico, Brazil, Chile, and Argentina does not reflect the meso- and microeconomies net deterioration in the living standards of rural and peri-rural urban areas. The middle class, which had become a sign of progress in several countries, also is adversely affected. This situation, added to the effect of extreme events, has exacerbated migration toward richer cities and countries with relatively better economies. Shantytowns have grown steadily around big cities, and poverty belts have even tripled. Their location in flood-prone valleys and unstable hills results in a lack of potable water and sanitation services, which is posing a serious threat to these cities.

Cultural (language, traditions, religion), economic (degree of development, economic systems, wealth distribution), and social (demographic growth, political systems and practices, educational systems) similarities in Latin American countries indicate that they could address climate change with common (shared) methods.

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