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for the same model. As expected, the main source of uncertainty for regional climate change scenarios is that associated with different projections from different GCMs. The analysis is much more complicated for rainfall changes. Different climate models show rather distinct patterns, even with almost opposite projections. In summary, the current GCMs do not produce projections of changes in the hydrological cycle at regional scales with confidence. In particular the uncertainty of projections of precipitation remain high (e.g., Boulanger et al., 2006a, b, for climate-change scenarios for South America using ten GCMs). That is a great limiting factor to the practical use of such projections for guiding active adaptation or mitigation policies.

GCM-derived scenarios are commonly downscaled using statistical or dynamical approaches to generate region- or site-specific scenarios. These approaches are described in detail in Chapter 11 of the Working Group I Fourth Assessment Report (Christensen et al., 2007). There have been a number of such exercises for South America using an array of GCM scenarios (HADCM3, ECHAM4, GFDL, CSIRO, CCC, etc.), usually for SRES emissions scenarios A2 and B2: for southern South America (Bidegain and Camilloni, 2004; Nunez et al., 2005; Solman et al., 2005a, b), Brazil (Marengo, 2004), Colombia (Eslava and Pabon, 2001; Pabon et al., 2001) and Mexico (Conde and Eakin, 2003). Downscaled scenarios may reveal smaller-scale phenomena associated with topographical features or mesoscale meteorological systems and land-use changes, but in general the uncertainty associated with using different GCMs as input is a dominant presence in the downscaled scenarios (Marengo and Ambrizzi, 2006).

13.3.1.2 Changes in the occurrence of extremes

Many of the current climate change studies indicate that the frequency in the occurrence of extreme events will increase in the future. Many impacts of climate change will be realised as the result of a change in the frequency of occurrence of extreme weather events such as windstorms, tornados, hail, heatwaves, gales, heavy precipitation or extreme temperatures over a few hours to several days. A limited number of studies on extremes from global models assessed during the AR4 (e.g., Tebaldi et al., 2007) provide estimates of frequency of seasonal temperature and precipitation extreme events as simulated in the present and by the end of 21st century under the A1B emissions scenario. In Central America, the projected time-averaged precipitation decrease is accompanied by more frequent dry extremes in all seasons. In South America, some models anticipate extremely wet seasons in the Amazon region and in southern South America, while others show the opposite tendency.

13.3.2 Land-use changes

Deforestation in Latin America's tropical areas will be one of the most serious environmental disasters faced in the region. Currently, Latin America is responsible for 4.3% of global GHG emissions. Of these, 48.3% result from deforestation and land-use changes (UNEP, 2000). By 2010 the forest areas in South and Central America will be reduced by 18 Mha and 1.2 Mha, respectively. These areas (see Figure 13.3) will be used for pasture and expanding livestock production (FAO, 2005).

If the 2002-2003 deforestation rate (2.3 Mha/yr) in Brazilian Amazonia continues indefinitely, then 100 Mha of forest (about 25% of the original forest) will have disappeared by the year 2020 (Laurance et al., 2005), while by 2050 (for a business-as-usual scenario) 269.8 Mha will be deforested (Moutinho and Schwartzman, 2005). By means of simulation models, Soares-Filho et al. (2005) estimated for Brazilian Amazonia that in the worst-case scenario, by 2050 the projected deforestation trend will eliminate 40% of the current 540 Mha of Amazon forests, releasing approximately 32 Pg (109 tonnes/ha) of carbon to the atmosphere. Moreover, under the current trend, agricultural expansion will eliminate two-thirds of the forest cover of five major watersheds and ten eco-regions, besides the loss of more than 40% of 164 mammalian species habitats.

Projected to be one of the main drivers of future land-use change, the area planted to soybeans in South America is

Land Use Change South America

Figure 13.3. Predicted 2000-2010 South American and Central American deforestation hotspots and diffuse deforestation areas (available at: http://www.virtualcentre.org/en/dec/neotropics/south_america.htm and http://www.virtualcentre.org/en/dec/neotropics/central_america.htm).

Figure 13.3. Predicted 2000-2010 South American and Central American deforestation hotspots and diffuse deforestation areas (available at: http://www.virtualcentre.org/en/dec/neotropics/south_america.htm and http://www.virtualcentre.org/en/dec/neotropics/central_america.htm).

expected to increase from 38 Mha in 2003/04 to 59 Mha in 2019/20 (Maarten Dros, 2004). The total production of Argentina, Brazil, Bolivia and Paraguay will rise by 85% to 172 million tonnes or 57% of world production. Direct and indirect conversion of natural habitats to accommodate this expansion amounts to 21.6 Mha. Habitats with the greatest predicted area losses are the Cerrado (9.6 Mha), dry and humid Chaco (the largest dry forest in South America, which covers parts of Argentina, Paraguay, Bolivia and Brazil; 6.3 Mha), Amazon transition and rain forests (3.6 Mha), Atlantic forest (1.3 Mha), Chiquitano forest (transition between Amazonian forest and Chaco forest; 0.5 Mha) and Yungas forest (0.2 Mha). This massive deforestation will have negative impacts on the biological diversity and ecosystem composition of South America as well as having important implications for regional and local climate conditions.

13.3.3 Development

133.3.1 Demographics and societies

The population of the Latin American region has continued to grow and is expected to be 50% larger than in 2000 by the year 2050. Its annual population growth rate has decreased and is expected to reach a value of 0.89% by 2015, which is considerably less than 1.9%, the average rate for the 1975-2002 period. The population has continued to migrate from the countryside to the cities, and by 2015 about 80% of the population will be urban, almost 30% more than in the 1960s. The population aged under 15 years will decline and at the same time the population aged over 65 years will increase. Total fertility rate (births per woman) decreased from 5.1 to 2.5 between 1970-1975 and 2000-2005 and is expected to decrease to 2.2 by 2015 (ECLAC, 1998).

According to ECLAC (1998) the number of people in an age-range making them dependent (between 0 and 14 and over 65 years) will increase from 54.8% at present to almost 60% in 2050. This will increase pressure on the social security systems in the region and increase the contributions that the population of working age will have to make in order to maintain the availability of health and educational services. Life expectancy at birth increased from 61.2 years in the 1970s to 72.1 years in the 2000-2005 five-year period, and is expected to increase to 74.4 years by 2015. Crude mortality rate is expected to increase from the current value of 7.8 (per thousand) to almost 12 by 2050.

Human migration has become an important issue in the region. Recent studies (ECLAC, 2002b) have estimated that 20 million Latin American and Caribbean nationals reside outside their countries, with the vast majority in North America. This phenomenon has important effects on national economies and creates important social dependencies: 5% of households in the region benefit from remittances which in 2003 amounted to US$38 billion (17.6% more than in 2002; IMO, 2005).

According to the Human Development Index, all countries in the region are classified within high and medium development ranks. In addition, Latin American countries are ranked within the upper half of the Human Poverty Index and have shown a systematic improvement between 1975 and 2002. It is difficult to ignore the fact that, although there are no Latin American countries classified in the low development rank, there are huge contrasts among and within countries in terms of levels of technological development, sophistication of financial sectors, export capacities and income distribution (CEPAL, 2002).

13.3.3.2 Economic scenarios

Projections of economic evolution for the region strongly depend on the interpretation of the results of the liberalisation process that the region has experienced during the last 20 years, and therefore can be contradictory. On the one hand, economists who favour liberalisation of Latin American economies argue that countries that have implemented these types of policies have improved in terms of growth rate, stability, democracy and even with regard to inequality and poverty (for example: Walton, 2004; World Bank, 2006). On the other hand, another group of experts in economics, sociology and politics is concerned with the effects that neoliberalisation has had for the region, especially in terms of increases in inequality and poverty, but also in terms of lack of economic growth (Huber and Solt, 2004). This is still an unresolved debate that imparts great uncertainty to economic scenarios for Latin America.

The first group's view provides the following insights for economic prospects. Analysts from the World Bank argue that while the real per capita GDP of Latin America has had a very low growth - about 1.3%/yr average during the 1990 to 2000 period - in the long term (from 2006 to 2015), regional GDP is projected to increase by 3.6%/yr, and per capita income is expected to rise by 2.3%/yr on average (World Bank, 2006). Current estimates forecast a growth of 4%/yr for the region in 2006 and 3.6%/yr in 2007 and real per capita GDP growth of 2.6%/yr and 2.3%/yr, respectively (Loser, 2006; World Bank, 2006). These positive prospects are attributed to the implementation of economic policies such as a substantial reduction of the fiscal imbalances and inflation control that have restrained growth in the past. According to this source, the area is on track to meet its Millennium Development Goals on poverty; however, it is important to note that the region's performance is not as good as other developing regions such as central Asia and, notably, China. An improvement on this rate of growth could be achieved by consolidating current economic policies (Walton, 2004; World Bank, 2006).

The second group of experts argue that the results of the liberalisation, far from establishing a sound basis for economic growth, have weakened the regional economy, reducing its rate of growth and making it more volatile, exacerbating social inequality and poverty, and limiting the region's capacity for future growth (Huber and Solt, 2004; Solimano and Soto, 2005). Lack of economic growth, inequality, a deficient legal framework and demographic pressures have been demonstrated to be important factors for increasing environmental depletion and vulnerability to climate variability and extreme events (CEPAL, 2002).

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