The regional scenarios document the possible impacts on emissions and air quality initiated by potential changes to policies on transportation, technology, fuel, and mobility systems during the upcoming decades. The intention of these scenarios is to show stakeholders that the implementation of sustainable policies plays a critical role in ensuring projected emissions do not become a reality (WEC, 2011).

The objective of this activity is to provide a source of information on current emissions projections and present scenarios for sustainable urban transport and climate change in Latin America and their potential impacts. These initially focus on Argentina, Brazil and Mexico.

1. Climate Change and Greenhouse Gas Emissions in Latin America

The greenhouse effect is a natural process that keeps the Earth’s surface around 30°C warmer than it would be otherwise. Without this effect, the Earth would be too cold to support life.  Certain types of molecules, chiefly carbon dioxide and water vapor, create a heat-trapping effect.  This means that more solar radiation reaches the earth’s surface than is radiated back into space.   Increasing the concentration of these gases in the atmosphere thus leads to an increased ability to trap energy and therefore changing surface temperatures.

The atmosphere is much more complicated than the simple models presented here suggests. The resulting warming from increases in these gases will in fact be much greater because of the interaction between feedbacks in the atmosphere that act to amplify the direct warming.  For example, the main positive feedback comes from water vapor, a very powerful greenhouse gas itself, which is likely to increase in the atmosphere as part of the warming process.

Source: Adapted from the Stern Review on the Economics of Climate Change.


According to the Intergovernmental Panel on Climate Change (IPCC), over the past century climate change has become more evident as the average global air and ocean temperatures increase. The melting of snow and ice, and the rise of global average sea levels are immediate consequences of climate change. Natural systems are being affected: enlargement and increased numbers of glacial lakes; ground instability; and changes in Arctic and Antarctic ecosystems are evidence of some of the effects. Eleven of the last twelve years have ranked among the twelve warmest years on record with respect to surface temperature.

Global and continental temperature change

Source: IPCC, Climate change 2007.


Climate change can therefore be defined as changes or variability in the average global environment over an extended period. The latter case has been an object of study, due to the important variations noticed in the atmosphere over the past century. High levels of gases in the atmosphere such as methane, carbon dioxide and nitrous oxide (greenhouse gases (GHGs)) have become a concern, and have been related almost primarily to the combustion of fossil fuels across a range of sectors. If this rate of emissions continues to grow, changes in the present century are expected to be larger than the ones observed previously (IPCC, 2007).

World CO2 Emissions From Fuel Combustion

Source: International Energy Agency (IEA, 2011).


GHG emissions have grown since pre-industrial times with an increase of 70% between 1970 and 2004 due to human activities (IPCC, 2007).  From 1971 to 2009 global CO2 emissions from fuel combustion has doubled with over 35% of this increase occurring since 2000.

Emissions from the heat and electricity generation sectors and transportation sectors are the major contributors to global emissions.  The demand for electricity is expected to continue to grow, because of a rapid population growth, particularly in developing countries, and the increase in demand for electrical devices used both domestically and commercially. Similarly, transportation emissions are anticipated to continue to grow due to increased vehicle ownership, the prevalence of inefficient vehicles in developing countries, and longer distances travelled. Developed countries have implemented a number of policies to reduce these emissions, by encouraging the use of more efficient vehicles and increasing use of public transportation (IEA, 2011).

Socio-economic indicators reflect societal attitudes towards the use of energy and resource limits. Emissions are intrinsically affected by increasing incomes, economic activities and population growth. Traditionally, the growth in emissions is related to growth in GDP, i.e. as countries develop economically their energy consumption also increases.  Decoupling these two factors is an important step towards slowing down the increase in emissions.  Improvements in this trend have been observed in countries such as USA, Japan, Russia and China with a shift to non-carbon-intensive fuels being the key factor (IEA, 2011).

As shown in the chart below, Latin America’s global share of CO2 emissions is small. In terms of emissions per capita, the world average in 2008 was 4.9 tonnes of CO2/capita and in Latin America was 2.16 tonnes of CO2/capita (IEA, 2009).  Nevertheless an increase is expected in the following decades due to rapid growth in road transportation. According to a study by University of California, Berkeley on climate change, using projections of passenger and freight activity, vehicle use and CO2 emissions, the overall CO2 emissions may have tripled by 2030 in Latin America. (Schipper, 2009).

Greenhouse emissions from fuel combustion

Source: International Energy Agency (IEA, 2011).


A quarter of all energy-related greenhouse gas emissions comes from transportation, which is now the fastest growing source of GHGs in the world (IEA, 2011). Many of the policies that must be considered to limit the emissions from this sector are most appropriate for countries that are building up their transportation systems.  Policies such as improved vehicle efficiency, minimizing the shift from public transport to the private vehicle and the use of low-carbon fuels can all contribute to minimizing the impact of this sector on GHG emissions (IEA, 2011).

 Per capita CO2 Emissions by sector in OECD Countries in 2009 (Total: 9.8 CO2 tonnes /capita)

Source: International Energy Agency (IEA, 2011).


Per capita CO2 Emissions by sector in Latin America in 2009 (Total: 9.2 CO2 tonnes /capita)

Source: International Energy Agency (IEA, 2011).


Within OECD countries 28% of the per capita CO2 emissions come from transportation (2.7 tonnes/capita equivalent to 3314 million tonnes of CO2).   According to the IPCC transport is the key to climate change, and GHGs must be reduced by 50–85% by 2050 comparatively to year 2000 as part of the 2° Celsius scenario. However, current trends show transport GHGs will increase 80-150% by 2050 with the majority of the growth in emissions coming from private motor vehicles in developing countries.

As shown in the chart for Latin America, 35% of the per capita CO2 emissions come from  transportation (3.3 tonnes/capita equivalent to 506 million tonnes of CO2).  Latin America therefore sees greater emissions per capita than developed countries and is the sector which has the greatest contribution to CO2 emissions.  As a result of increased incomes, economic activity and population growth (i.e. improved GDP) CO2 emissions are likely to increase rapidly from land transportation.  As a result, it is expected to reach 770 million tonnes of CO2 by 2020 and 1413 million tonnes of CO2 by 2050.

In order to mitigate CO2 emissions there are different policies that should be implemented. To reduce the growth of land transportation, the quality of transit and non-motorized travel in LAC cities must be improved. Low-carbon fuels and new vehicle technologies are a good option; as well as a major improvement in urban transport pedestrian and bicycle facilities, traffic management and appropriate pricing of transport facilities and services (Schipper, 2009).

A global commitment to sustainable mobility requires the implementation of a set of best practices and strategies contained in a new sustainable transport policy paradigm for passenger and freight transport, known as “Avoid, Shift, Improve” (ASI). ASI Best Practices focus on access while avoiding unnecessary motorized trips with smarter land use planning, pricing, and technology; shifting trips to more sustainable modes through price incentives, better information, and improved service quality; and improving vehicle efficiency with cleaner fuels, improved network management, and more efficient vehicle technology. All the elements of ASI have been demonstrated at scale (GTZ, 2010).

In order to change the trend, there are many opportunities in sustainable growth policies and challenges for transport policy-makers in LAC. Governments could evaluate the most cost?effective actions based on marginal abatement costs and implement many policies on transport sector GHG mitigation avoiding unnecessary costs. Success will depend on action across several fronts encompassing technology, fuels, and travel behavior. Governments and regional circumstances will play an important role in determining the allocation of effort (OECD/ITF, 2009).