The intergovernmental Panel on Climate Change (IPCC) has finalized its assessment of present and future impacts of climate change, and concluded that the world’s rivers, lakes, wildlife, glaciers, coastal zones and many other elements of the natural and physical environment are showing the discernable effects of human-caused global warning.
In regards to Latin America, a region highly heterogeneous in terms of climate, ecosystems, human population distribution and cultural traditions, the IPCC reports state “highly unusual extreme weather events” since1992 and until now in various LAC regions, with negative impacts on populations, increasing mortality and morbidity in affected areas.
The conclusion reports that in Latin America and the Caribbean there are several evidences of increases in extreme climatic events and climate change, and that the frequency of weather and climate extremes is most likely to increase.
By 2050, the population in Latin America is likely to be 50% larger than in 2000, and migration from the country sides to the cities will continue.
Predicted changes are very likely to severely affect a number of ecosystems and sectors by:
Climatic change and variability
Extreme events have been severely affecting the Latin America (LA) region over recent years. During the last decades important changes in precipitation and increases in temperatures were observed, and the projected mean warning for LA to the end of the century, according to different climate models, ranges from 1 to 4° C or 2° to 6°.
Increase of temperature of approximately 1°C in Mesoamerica and South America, and of 0.5° in Brazil was recorded. Over the past three decades, Latin America was subjected to climate-related impacts of increased El Niño occurrences. Two extremely intense episodes of El Niño phenomenon (1982-83 and 1997-98) and other increased climate extremes occurred during this period, contributing greatly to the vulnerability of human systems to natural disasters (floods, droughts, landslides.)
The occurrence of climate-related disasters increased by 2.4 times between the periods 1970-1999 and 2000-2005, continuing the trend observed during the 1990s. Only 19% of the events have been economically quantified between 2000 and 2005, representing losses of near 20 billion US$. In addition to weather and climate, the main drivers of the increased vulnerability are demographic pressure, unregulated urban growth, poverty and rural migration, low investment in infrastructure and services, and problems in inter-sector coordination.
Landslides are generated by intense/persistent precipitation events and rainstorms. Furthermore, in LA they are associated with deforestation and lack of land planning and disaster warning systems. Many Latin American cities, already vulnerable to landslides and mudflows, are very likely to suffer the exacerbation of extreme events with increasing risks/hazards for the local populations.
The poorest communities are among the most vulnerable to extreme events, and some of these vulnerabilities are caused by their location in the path of hurricanes (about 8.4 million people in Central America), on unstable lands, in precarious settlements, on low-lying areas, and in places prone to flooding from rivers.
Tropical forests of Latin America, particularly those of the Amazonia, are increasingly susceptible to fire occurrences due to increased El Niño-related droughts and to land-use change (deforestation, selective logging and forest fragmentation).
Mangrove forests located in low-lying coastal areas are particularly vulnerable to sea level rise, increased mean temperatures, and hurricane frequency and intensity, especially those of Mexico, Central America and Caribbean continental regions.
Increased rainfall in southeast Brazil, Paraguay, Uruguay, the Argentinean Pampas and some parts of Bolivia has impacts on land use, crop yields and has increased flood frequency and intensity. On the other hand, a declining trend in precipitation has been observed in southern Chile, southwest Argentina, southern Peru, and western Central America.
In relation to land, the IPCC report said that “almost three quarters of the dry-land surface are moderately or severely affected by degradation processes. The combined effects of human action and climate change have brought a continuous decline of natural land cover which continues to decline at very high rates. There is evidence that biomass burning may change regional temperatures and precipitations in the southern part of the Amazonia. Biomass burning also affects regional air quality, with implications on human health”.
The impact of ENSO (El Niño, Oscilación del Sur) and related climate variability on the agricultural sector has been well documented in the TAR (IPCC, 2001). Most recent findings include high/low wheat yields during El Niño/La Niña in Sonora-Mexico.
In 1990, the total forest area in Latin America was 1,011 Mha, and it was reduced by 46.7 Mha in ten years (UNEP 2003a). The expansion of the agricultural frontier and livestock, selective logging, financing of big scale projects like construction of dams for energy generation, illegal crops, construction of roads and increased links to commercial markets have been the main causes of deforestation (FAO, 2001a).
Land use changes have intensified the use of natural resources and exacerbated many of the processes of land degradation. By the 2050´s, 50% of agricultural lands are very likely to be subjected to desertification and salinization, affecting 17 50% of agricultural lands in Latin America and the Caribbean zone (FAO, 2004a). Furthermore, the combined effects of climate change and land-use change on food production and food security are related to a larger degradation of lands and a change on erosion patterns (FAO, 11 2001b).
However, some adaptive measures like changes in land use, sustainable management, insurance mechanisms, irrigation, adapted genotypes and changes in agronomic crop management, are used in the agricultural sector to cope with climatic variability. Also, economic diversification has long been a strategy for managing risk (both climatic and market) and has increased in recent years.
Several studies using crop simulation models and future climate scenarios were carried out in LA for commercial annual crops.
According to a global assessment, if CO2 effects are not considered, grain yield reductions could reach up to 30% by 2080 under the warmer scenario, and additional people at risk of hunger is likely to attain 5, 26 and 85 millions in 2020, 2050 and 2080 respectively; the World Bank Report (2002a) states that some developing countries are losing 4-8% 12 of their Gross Domestic Product, caused by productive and capital loss related to environmental degradation.
The demand of water for irrigation is projected to rise in a warmer climate, bringing increased competition between agriculture and drinking as well as industrial users, making the practice of agriculture more expensive. Under severe dry conditions, inappropriate agricultural practices (deforestation, soil erosion, chemical abusive use) will deteriorate surface and groundwater quantity and quality.
Generalized reductions of rice yields by the 2020´s as well as increased in soybean yields are possible when CO2 effects are considered. On the other hand, cattle and dairy productivity is expected to decline in response to increasing temperatures.
In global terms, Latin America is recognized as a region with large freshwater resources. However, the irregular temporal and spatial distribution of these resources affects its availability and quality, in different regions.
Hydropower is the main electrical energy source for most countries in LA and vulnerable to large-scale and persistent rainfall anomalies. A combination of increased energy demand and droughts caused a virtual breakdown of hydroelectricity in most of Brazil in 2001 that contributed to a GDP reduction of 1.5%.
Almost 13.9% of the population in Latin America has no access to safe water supply, and 63% lives in rural areas (IDB, 2004). Many rural communities rely on limited freshwater resources (surface or underground) and many others on rainwater, using water cropping methods which are very vulnerable to droughts (IDB, 2004)
The current vulnerabilities observed in many regions of LA countries will be increased by the joint negative effect of growing demands due to an increasing population rate for water supply and irrigation, and the expected drier conditions in many basins. Therefore, taking into account the number of people experiencing decreased water stress, there is still a net increase in the numbers of people becoming water stressed.
The glacier retreat trend reported in the TAR is being exacerbated, reaching critical conditions in Bolivia, Peru, Colombia and Ecuador. Recent studies indicate that most of the South American glaciers from Colombia to Chile and Argentina (up to 25ºS) are drastically reducing their volume at an accelerated rate. Changes in temperature and humidity are the primary cause for the observed glacier retreat during the 2nd half of the 20th century in the tropical Andes. In the next 15 years inter-tropical glaciers are very likely to disappear, affecting water availability and hydropower generation.
The lack of adaptation strategies in LA to cope with the hazards and risks of floods and droughts, is due to low GNPs, the increasing population settling in vulnerable areas (flood, landslide, drought-prone), and the lack of appropriate (poorly developed) political, institutional and technological framework. Nevertheless, some communities and cities have organized themselves, becoming more active in disaster prevention.
Accelerated urban growth, increasing poverty and low investment in water supply will contribute to water shortages in many cities, to high percentages of urban population without access to sanitation services, to an absence of treatment plants, high groundwater pollution and lack of urban drainage systems, to storm sewers used for domestic waste disposal and occupation of flood valley without control during drought seasons and high impacts during flood seasons.
By the 2020s the net increase in the number of people experiencing water stress due to climate change is likely to be between 7 and 77 million. For the second half of the century these numbers could reach between 60 and 150 million.
The expected increase in Sea Level Rise (SLR), weather and climatic variability and extremes are very likely to affect coastal areas. During the last 10-20 years, the rate of SLR increased from 1 to 2-3 mm/year in south-eastern South America. In particular, sea level rise is very likely to affect the Mesoamerican coral reefs of Mexico, Belize and Panama, and the location of fish stocks in the south-east Pacifica (Peru, Chile).
Low-lying coasts, in several LA countries (i.e. part of Argentina, Belize, Colombia, Costa Rica, Ecuador, Guyana, Mexico, Panama, El Salvador, Uruguay, Venezuela) and large cities (Buenos Aires, Rio de Janeiro, Recife, etc.) are among the most vulnerable to climate variability and extreme hydro-meteorological events such as rain and windstorms and subtropical and tropical cyclones (i.e. hurricanes) and their associated storm surges. SLR (within the range 10-20 cm/century) is not a main problem yet, but evidences of acceleration of SLR rates (up to 2-3 mm/y) over the past decade suggest an increase in the vulnerability of low-lying coasts, already subjected to increasing storm surges.
Several LA countries have developed planned and autonomous adaptation measures in response to current climate variability impacts on their coasts. Most of them (i.e., Argentina, Colombia, Costa Rica, Uruguay and Venezuela) focus their adaptation on integrated coastal management. The Caribbean Planning for Adaptation to Global Climate Change project is promoting actions to assess vulnerability (especially regarding the rise in sea level), and plans for adaptation and development of appropriate capacities (CATHALAC, 2003). Since 2000, some countries have been improving the legal framework on matters related to establishing restrictions on air pollution and integrated marine and coastal regulation.
In Belize and Guyana, the implementation of land-use planning and zoning imposed strengthen norms for infrastructure, a coastal zone management plan, the adjustment of building codes and better disaster mitigation strategies (including floodplain and other hazard mapping) to couple with climate change considerations into the day-to-day management of all sectors.
Significant impacts of projected climate change and sea level rise are expected for 2050-2080 on the LA coastal areas. With most of their population, economic activities and infrastructure located at or near sea-level, they will very likely suffer flooding and erosion with high impacts on people, resources and economic activities.
As for coastal tourism, the most impacted countries will be those where the sector contribution to the GDP, Balance of Payment and employment is relatively high, and are threatened by windstorms and projected sea level rise, such as those of Central America, the Caribbean coast of South America and Uruguay. Thus, climate change is very likely to be a major challenge for all coastal nations.
After the onset of El Niño (dry/hot) there is a risk of epidemic malaria in coastal regions of Colombia and Venezuela. Droughts favor the development of epidemics in Colombia and Guyana, while flooding engenders epidemics in the dry northern coastal region of Peru. Annual variations in dengue/dengue hemorrhagic fever in Honduras and Nicaragua appear to be related to climate-driven fluctuations (temperature, humidity, solar radiation and rainfall). In some coastal areas of the Gulf of Mexico, an increase of sea surface temperature (SST), minimum temperature and precipitation was associated with an increase of dengue transmission cycles.
The regional assessments of health impacts due to climate change in the Americas show that the main concerns are heat stress, malaria, dengue, cholera and other water-borne diseases. Malaria continues to pose a serious health risk in LA, where 262 million people (31% of population) live in tropical and subtropical regions with some potential risk of transmission.
Climate change is likely to increase the risk of forest fires. In some countries, wildfires and intentional forest fires have been associated to increase risk of outpatients’ visits, for respiratory diseases and increase risk of breathing problems.
Highly unusual ozone loss and UV-B increases have occurred in the Punta Arenas (Chile) area over the past two decades resulting in the population being repeatedly exposed to an altered solar UV spectrum with a greater effectiveness for erythemae and photo-carcinogenesis.
Under future climate change, there is a risk of significant species extinctions in many areas of tropical LA. Since 1980, about 20% of the world's mangrove forests have disappeared (FAO, 2006) affecting fishing. In the Mesoamerican reef there are as many as 25 times more fish of some species on reefs close to mangrove areas than in areas where mangroves have been already cut down.
Ecological corridors between protected areas have been planned for the maintenance of biodiversity in natural ecosystems. Some of these, such as the Mesoamerican Biological Corridor, have been implemented serving also as adaptation measures.
Conservation efforts would be also devoted to implement protection corridors containing mangroves, sea grass beds, and coral reefs to boost fish abundance on reefs, benefit local fishing communities, and contribute to sustainable livelihoods. Other positive practices in the region are oriented to maintaining and restoring native ecosystems, protecting and enhancing ecosystem services like carbon sequestration as in the Noel Kempff Mercado Climate Action Project in Bolivia. Conservation of biodiversity and maintenance of ecosystem structure and function are important for climate change adaptation strategies due to the protection of genetically-diverse populations and species-rich ecosystems; an example is the initiative to implement adaptation measures in high mountain regions developed in Colombia and other Andean countries. A new option to promote mountainous forest conservation consists in compensating forest owners for environmental services. The compensation is often financed by charging a small price to water users, for the water originated in forests. Such schemes are being implemented in various countries of LA and were tested in Costa Rica.
Global Climate Models-derived scenarios are commonly downscaled using statistical or dynamical approaches to generate region- or site-specific scenarios.
Downscaled scenarios may reveal smaller scale phenomenon associated with topographic features or 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. However, most current climate-change studies indicate that the frequency in the occurrence of extreme events will increase in the future.
Urgent measures must be taken to help bring environmental and social considerations from the margins to the decision-making and development strategies, and important multidisciplinary research efforts are required to reduce the information gaps needed for decision-making.
In preparing for the challenges that climate change is posing the region, research priorities should be to resolve the constraints already identified in terms of facing current climate variability and trends, such as: lack of awareness, of well-distributed and reliable observation systems, of adequate monitoring systems and technical capabilities, of investment and credits for the development of infrastructure in rural areas, of integrated assessments, mainly between sectors, of limited studies on the economic impacts of current and future climate variability and change, and of restricted studies on the impacts of climate change on societies, including the lack of clear priorities in the treatment of topics for the region as a whole.
In addition, other priorities considering climate change are to reduce uncertainties in future projections and to assess the impacts of different policy options on reducing vulnerability and/or increasing adaptive capacity. We must also change the attitude from planning to effective operation of observation and alert systems. A necessary change would be to migrate from a culture of response to a culture of prevention.
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