Latin America

14 Latin America LUIS JOSE MATA (VENEZUELA) AND MAX CAMPOS (COSTA RICA) Lead Authors: E. Basso (Chile), R. Compagnucci (Argentina), P. Fearnside (Brazil), G. Magrin (Argentina), J. Marengo (Brazil), A.R. Moreno (Mexico), A. Suárez (Cuba), S. Solman (Argentina), A.Villamizar (Venezuela), L. Villers (Mexico) Contributing Authors: F. Argenal (Honduras), C. Artigas (Chile), M. Cabido (Argentina), J. Codignotto (Argentina), U. Confalonieri (Brazil), V. Magaña (Mexico), B. Morales-Arnao (Peru), O. Oropeza (Mexico), J.D. Pabón (Colombia), J. Paz (Peru), O. Paz (Bolivia), F. Picado (Nicaragua), G. Poveda (Colombia), J. Tarazona (Peru), W. Vargas (Argentina) Review Editor: C. Nobre (Brazil) CONTENTS Executive Summary 69 5 14 . 2 . 2 . Agriculture and Plantation Forestry 71 3 14 . 2 . 2 . 1 . Arable Farming and Tree Crops 71 3 14 . 1 . The Latin America Region 69 9 14 . 2 . 2 . 2 . Ranching 71 4 14 . 1 . 1 . What is Unique about 14 . 2 . 2 . 3 . Plantation Silviculture 71 5 the Latin America Region? 69 9 14 . 2 . 3 Sea-Level Rise 71 6 14 . 1 . 2 . Climate Variability and Change 70 0 14 . 2 . 3 . 1 . General Impacts 71 6 14 . 1 . 2 . 1 . Past to Present 70 0 14 . 2 . 3 . 2 . Ecological and 14 . 1 . 2 . 2 . Future: Climate Scenarios 70 3 Local Community Val u e s 71 7 14 . 1 . 3 . Socioeconomic and 14 . 2 . 4 . Water Resources: Availability and Use 71 8 Trade Agreements Issues 70 5 14 . 2 . 5 . Human Health 71 8 14 . 1 . 3 . 1 . Socioeconomic Issues 70 5 1 4 . 2 . 5 . 1 .E ffects of Changes in 14 . 1 . 3 . 2 . Trade Ag r e e m e n t s 70 6 Climate Variables on Health 71 8 14 . 1 . 4 . Environmental Legislation 70 6 14 . 2 . 5 . 2 . Vec t o r -Borne Diseases 72 0 14 . 1 . 5 . Summary of Main Findings from 14 . 2 . 5 . 3 . Wat e r -Borne Diseases 72 0 the IPCC Special Report 1 4 . 2 . 5 . 4 .E ffects of El Niño on Regional Impacts of Climate Change 70 7 Phenomenon on Health 72 1 1 4 . 2 . 5 . 5 .E ffects on Food 14 . 2 . Key Regional Concerns 70 8 Production and Safety 72 1 14 . 2 . 1 . Natural Ecosystems 70 8 14 . 2 . 1 . 1 . Humid Tropical Forests 70 8 14 . 3 . Sy n t h e s i s 72 2 14 . 2 . 1 . 2 . Dry Forests 71 0 14 . 2 . 1 . 3 . Savannas, Grasslands, Ac k n o w l e d g m e n t s 72 4 and Deserts 71 0 14 . 2 . 1 . 4 . Temperate Forests and Re f e re n c e s 72 4 Mountain and Polar Ecosystems 71 0 14 . 2 . 1 . 5 . Biodiversity 71 3 EXECUTIVE SUMMARY The Latin America region is remarkably heterogeneous in Argentina, do not show well-defined trends. This suggests, for terms of climate, ecosystems, human population distribution, instance, an increase in precipitation in some regions of the and cultural traditions. Land-use changes have become a major mid-latitude Americas. force driving ecosystem changes. Complex climatic patterns, which result in part from interactions of atmospheric flow with The Amazon River—by far the world’s largest river in terms of topography, intermingled with land-use and land-cover change, streamflow—plays an important role in the water cycle and make it difficult to identify common patterns of vulnerability water balance of much of South America. Several model studies to climate change in the region. Water resources, ecosystems, and field experiments show that about 50% of the rainfall in agriculture and plantation forestry, sea-level rise, and human the region originates as water recycled in the forest. In the health may be considered the most important among the various Amazon region, even small changes in evapotranspiration sectors that may be impacted by climate change. affect water vapor fluxes. Therefore, deforestation is likely to reduce precipitation because of a decrease in evapotranspiration, leading to important runoff losses in areas within and beyond Climate, Extreme Events, and Water Resources this basin. Any reductions in rainfall would affect not only Amazonia but also Brazil’s central-south region, where most of In most of Latin America, there are no clear long-term tendencies the country’s agriculture and silviculture are located. However, in mean surface temperature. Some changes in regional with the current rate of deforestation of no more than 10% in a t m o spheric circulation have been detected. For instance, the Amazonia as a whole, discharge observations across the basin south Atlantic anticyclone has intensified, and the subtropical do not exhibit, to date, any significant trends. jet stream in South America has shifted south. These phenomena may be a sign of changes associated with climate change as Although it is expected that tropical storms (e.g., tropical they already are impacted by the El Niño-Southern Oscillation cyclones) will increase their peak intensity under global warming (ENSO) phenomena and extreme events. (see Table 3-10), only some hints of such intensification in the tropical cyclones affecting the Americas have been detected. The cryosphere in Latin America, which is composed of glaciers Some studies based on model experiments suggest that under in the high Andes and three major ice areas in southern South climate change the hydrological cycle will be more intense, America, may be severely affected by global warming. It has with changes in the distribution of extreme heavy rainfall, wet been well established that glaciers in Latin America, particularly spells, and dry spells. Frequent severe droughts in Mexico during along the tropical Andes, have receded in recent decades. the past decade coincide with some of these model findings. Glaciers contribute to streamflow in rivers of semi-arid and Even though it is uncertain how global warming may affect the arid areas of South America. Streamflows in Andean rivers— frequency and intensity of some extreme events, the infrequent for example, in northwest Peru—exhibit tendencies that may overlapping of hydrological and weather/climate events be related to glacial extent changes before and after the mid- h i s t o rically have given rise to disasters, whose frequency may 1970s. However, there also is evidence that rainfall and river be enhanced by such warming. flows in other regions of Latin America correspond only to interdecadal variability in the hydrological cycle. For instance, rainfall and streamflow in Amazonia and northeast Brazil El Niño exhibit interdecadal variability linked to Pacific and Atlantic Ocean influences. Warming in high mountains also could It also has been suggested that under climate change, more affect mountain sports and tourist activities, which represent an El Niño-like mean conditions will be experienced. El Niño important source of income in the economies of some countries d i fferentially influences precipitation and temperature in in the region. d i fferent parts of the region; for example, it is related to dry conditions in northern northeast Brazil, northern Amazonia, and At a subregional level, precipitation trends in Latin America the Peruvian-Bolivian Altiplano. Southern Brazil and northwest vary. Precipitation trends depend on the location and the length Peru exhibit anomalously wet conditions during these periods. of the time series under study. For instance, negative trends in In Mexico and the Caribbean coast of Central America, there is some parts of Central America (e.g., Nicaragua) contrast with compelling evidence of more winter precipitation and less positive trends in northeastern Argentina, southern Brazil, and summer precipitation during El Niño. Some of the most severe northwestern Mexico. Other regions, such as central-western droughts in Mexico in recent decades have occurred during 696 Latin America El Niño years. During the 1997–1998 El Niño event, droughts p o pulation. Under climate change conditions, subsistence occurred in Amazonia, Mexico, and Central America, favoring farming could be severely threatened in some parts of Latin forest fires. Under climate change conditions, the number of America, such as northeastern Brazil. forest fires may increase. Studies in Argentina, Brazil, Chile, Mexico, and Uruguay based on general circulation models (GCMs) and crop models Natural Ecosystems project decreased yields in several crops (e.g., maize, wheat, barley, grapes), even when the direct effect of carbon dioxide Latin America contains a large percentage of the world’s (C O 2) fertilization and the implementation of moderate adaptation b i od i v e r s i t y, and climate change could accelerate losses in measures at the farm level are considered. It is likely that b i odiversity that already are occurring. Some adverse impacts increases in temperature will reduce crop yields in the region on species that can be related to regional changes in climate by shortening the crop cycle. However, the lack of consistency have been observed. Studies show that climatic changes in the various GCM precipitation scenarios makes it difficult to already are affecting frogs and small mammals in Central have a precise scenario for crop production under climate America. The tropical forests play an important role in the change, even when the relationships between precipitation and hydrological cycle of much of South America. Several model crop yields are well known. Increased temperature, ultraviolet studies and field experiments show that a large part of the radiation, sea-level rise, and changes in pest ecology may r a i nfall in the region originates as water recycled in the forest. threaten food production as well (e.g., in Argentina). Climate Large-scale deforestation is likely to result in increased surface change may reduce silvicultural yields as a result of changes in temperatures, decreased evapotranspiration, and reduced water availability during the dry season.

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