Climate Change and Transport

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Anthropologic greenhouse gas (GHG) emissions from transport are key contributor to global climate change. Carbon dioxide (CO2) represents the largest proportion of GHG emissions. Over the past three decades, CO2 emissions from transport have risen faster than those from all other sectors and are projected to rise more rapidly. At present industrialized countries are the main sources of transport emissions. However, the proportion of emissions being produced in developing countries is increasing rapidly. The majority of transport fuel emissions (76%) are from road transport, including four-wheeled vehicles and personal pickup trucks. Air travel produces around 12% of transport CO2 emissions and its share is growing rapidly.

Transport’s Contribution to Man-made Emissions

In addressing the impacts of climate change through sustainable transport instruments, cities are also able to benefit from a range of advantages including improved air quality, reduced noise disturbance, or increased road safety. Moreover, social and economic benefits can be expected.

Surface warming at the end of the 21st century
Surface warming at the end of the 21st century

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Sustainable Transport Instruments

Figure 1: Overview of Sustainable Transport Instruments (source Dalkmann et. al. 2010)
Overview of Sustainable Transport Instruments (Dalkmann et. al. 2010)


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Planning Instruments

Land use planning: Smart infrastructure design will influence both the demand for and the efficiency of transport. “Mixed land use” mixes the various forms of land use like housing, working, shopping, or public services within one city quarter. A smart mixture can significantly reduce the need to travel or distances travelled and thus decrease energy consumption and emissions. Good access to public transport can also be a major contributor to cutting emissions. Parking management can affect the relative price and convenience of driving.

Planning for public transport modes: Public transport includes buses, rail, light rail, metro, and underground systems. Attractive, accessible and reliable public transport systems can provide the basis for alternative mode use in cities. Expansion of the systems and services or improving the operation of systems helps to improve public transport. A sufficient ridership is required to avoid transit vehicles running at half occupancy.

Planning for non-motorized modes: Cycling and walking do not produce direct emissions. Creating continuous cycle networks, separating cycle lanes, or integrating with other transport modes encourage cycling and walking. Support instruments are awareness campaigns and information, which may also include cycling and walking routes and maps.

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Regulatory Instruments

Physical restraint measures: These measures include physical restriction to access certain motorized vehicles reducing traffic volumes and associated GHG emissions. One such measure is the restriction of vehicles on certain days depending on their registration plate number. To avoid second car purchases such schemes should be well-designed and limited to restrictions during peak periods.

Low emissions zones: Low emissions zones are areas into which access is allowed only to vehicles meeting a prescribed standard of emission. Such restrictions have benefits for local air quality improvements and for GHG emission reductions, if the area is big enough. However, this instrument requires a high level of administration and technology to set up and enforce the restrictions.

Traffic management measures: Traffic management measures smooth traffic flows and thus helps to ease congestion and improve fuel efficiency. Area traffic control systems, where signals are linked across a whole network, are most efficient. In developed countries, traffic management has been estimated to reduce emissions by 2% to 5%. There is potential for similar benefits in developing cities due to the poor initial traffic considerations.

Regulation of parking supply: Parking supply restrictions can make car use unattractive and thus contribute to mode shift. In addition, illegal parking must be avoided, e.g. by providing bollards on pavements. Transport authorities should also work in partnership with employers and other commercial business, which have a role to play in reducing private parking allocations reserved for employees.

Speed restrictions: At higher speeds (generally above 55 km/h) fuel consumption is often an increasing function of speed for cars and trucks. In order to reduce emissions, the implementation of lower speed limits should be considered.

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Economic Instruments

Road priding: In general, road pricing increases the cost of running a vehicle thus encouraging the use of alternative modes. Key factors that affect the effectiveness of road pricing include: the level of fee charged, the current cost of driving per kilometer, responsiveness of travelers to the price of travel, and the nature and extent of pricing. The two main road pricing options are: national pricing schemes, where charges are applied to long-distance highway use, and local road pricing schemes, which typically cover city center areas.

Fuel taxation: Fuel taxes are a way of charging the users of transport infrastructure relative to individual use. Fuel taxation raises the price of travel per kilometer and fuel taxation is directly proportional to fuel consumption. Both effects can contribute to reducing GHG emissions.

Vehicle taxation: 0.85em;">: The main principle behind vehicle taxation is to charge vehicle ownership. There are two key forms of vehicle taxation: Sales taxes are charged when the vehicle is purchased, sometimes contributing significantly to the overall cost of the vehicle. Annual vehicle taxes/registration fees are a continuous financial burden rather than a one-off tax. They also apply to all vehicles rather than just new ones. Vehicle taxes can be differentiated according to vehicle type, vehicle size or emissions, and noise levels.

Parking pricing: Parking pricing increases the cost of using a vehicle by raising the cost of parking. To increase the effectiveness of parking pricing, it should be coupled with limits to the physical availability of parking spaces, and it is recommended to introduce it on a region-wide basis.

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Information Instruments

Public awareness campaigns and mobility management: Public awareness campaigns can take many forms. Most often they are used to inform the public about the travel alternatives available to them or about the environmental, economic and social impacts of transport. Marketing of sustainable transport solutions is essential when attempting to secure public acceptance.

Driver behavior training and education/eco-driving: Through the provision of Eco-Driving education and training, driver behavior may be altered to achieve greater fuel efficiencies. Key methods of improving fuel efficiency can relate to driving style/behavior (speed, braking and acceleration, engine idling, carrying capacity and cold starts) and vehicle condition (maintenance-engine, tires, oil and air filter, and vehicle age). Driver training is particularly effective when commercial vehicles, such as bus, taxi or freight fleets, are included.

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Technology Improvements and Instruments

The key aims in order to achieve reduced GHG emissions from transport are to change travel behavior and/or the technology used. Technology improvements often focus on fuels, propulsion technology, other vehicle attributes, and use of communication and information technologies. They may sometimes seem to be easier to implement than policies that may restrain vehicle demand and use, primarily as they require less behavioral and lifestyle change. However, technology improvements are most effective when implemented in conjunction with other instruments within a larger strategy.

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Strategies to Reduce Emissions of Greenhouse Gas Emissions

A Comprehensive Approach

Evidence suggests that a comprehensive sustainable urban transport approach that takes advantage of a variety of instruments will have a larger impact on emission reductions and will result in a more co-benefits through the improvement of local transport systems. Taking a comprehensive approach will typically include, e.g., the provision of cycling and walking facilities, attractive and reliable alternatives to the private vehicle, it will make use of measures that restrict the use of the car, it will help establish good land use planning practices; and it will promote technological improvements such as cleaner fuels; it will set (monetary) incentives by applying appropriate economic instruments.

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Potential Strategy Outcomes – Greenhouse Gas Emission Reductions and Co-benefits

The level of greenhouse gas reduction that could be achieved as a result of individual instruments is difficult to predict. Reductions are most likely to be achieved where a higher share of public transport or non-motorized modes is attained.

The largest CO2 reduction can be achieved by the implementation of a package of measures, including Bus Rapid Transit (BRT), pedestrian upgrades and cycle ways. This is estimated to result in a reduction of more than 12 million tons of CO2 from the baseline at mitigation costs of US$30 per ton of CO2.

A range of co-benefits can be achieved through the implementation of sustainable transport instruments. Co-benefits include health and safety, the economy, accessibility to key services and activities and air pollution.

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Financial Mechanisms to Tackle Climate Change

Clean Development Mechanism (CDM)

The CDM allows industrialized countries with a greenhouse gas reduction commitment under the Kyoto Protocol to invest in emission reducing projects in developing countries. These are usually alternatives to what is considered to be more costly emission reductions in their own country. CDM projects provide additional funds for investment in developing countries and can lead to better infrastructure and technology. Investment using that mechanism should lead to sustainable development as projects are assessed for their impact on reducing GHG emissions. For developed countries the benefits of getting involved in the CDM is that they will be able to implement GHG emissions at lower costs than in their own country.

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Global Environment Facility (GEF)

The GEFwas set up to fund projects and programs aimed to protect the global environment. It only proved co-funding; a significant contribution to financing of the project needs to come from other sources. Projects can include biodiversity, climate change, international waters, land degradation, the ozone layer and persistent organic pollutants.

By using the GEF developing countries and cities can mobilize additional funding to implement projects that are their core interest. In the transport sector, co-funding from the GEF can be used to improve public transport or promote non-motorized transport. To be eligible for GEF funding, projects must have a benefit for the global environment and fulfill specific formal criteria.

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Transport is one of the key sources of GHG emissions. In order to effectively reduce global GHG emissions, developing cities with dramatically increasing populations and emissions will have to address climate change issues and contribute to its mitigation. The comprehensive approach that sustainable urban transport policies offer is a way forward to meet the needs for transport and mobility in an environmentally, socially and economically sustainable way.

Decision-makers and city administrations may have concerns regarding the impact of reducing the level of motorized transport on the economy. But there is evidence to suggest that by encouraging travel by sustainable transport modes GDP can continue to grow and economies can continue to develop. Sustainable urban transport can improve the local environment, reduce local air pollution and congestion levels – and thus make cities more desirable places to live, work, and visit.

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Further Information

  • Further and more detailed information can be found on the homepage of the Sustainable Urban Transport Project (SUTP). The Sustainable Urban Transport Project aims to help developing world cities achieve their sustainable transport goals, through the dissemination of information about international experience, policy advice, training and capacity building.
  • Climate Mitigation and Adaptation


  1. Dalkmann, H. et al., 2010. Transport and Climate Change, Module 5e. Sustainable Transport: A Sourcebook for Policy-makers in Developing Cities, Eschborn: Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ) GmbH.