Tracking Transport

More efforts needed
Robert Ruggiero 3ci1ysp1e7w Unsplash
In this report

Global transport emissions increased by only 0.6% in 2018 (compared with 1.6% annually in the past decade) owing to efficiency improvements, electrification and greater use of biofuels. Transportation is responsible for 24% of direct CO2 emissions from fuel combustion. Road vehicles – cars, trucks, buses and two- and three-wheelers – account for nearly three-quarters of transport CO2 emissions. Emissions from aviation and shipping continue to rise, indicating that these hard-to-abate subsectors need more international action.

Transport sector CO2 emissions in the Sustainable Development Scenario, 2000-2030

Tracking progress

The transport sector is in a critical transition, in which existing measures to increase efficiency and reduce energy demand must be deepened and extended for compliance with the Sustainable Development Scenario (SDS).

This process should be set in motion over the next decade, as any delay would require that stricter measures be taken beyond 2030, which could noticeably raise the cost of reaching climate targets. Combined efforts across all transport modes, accompanied by power sector decarbonisation, will play a crucial role for achieving SDS goals.

Although energy demand and emissions from aviation and shipping have been increasing steadily, they have also continued to rise in all modes of road transport (cars, trucks, buses and two- and three-wheelers). As a result, the road share of total transport emissions has remained relatively stable since the turn of the century.

Road transport emissions have increased despite progress in electrification: the global share of electric car sales rose to more than 2.5% in 2018, and fleets of electric buses and trucks are being procured in more and more cities around the world. Therefore, continued growth in emissions is due largely to:

  • Car buyers continuing to purchase larger, heavier vehicles, not only in the United States but increasingly in Europe and Asia. In Europe, the preference for larger cars, together with plummeting shares of more efficient diesel cars, is outweighing the impact of higher shares of electric car sales and caused the average new car CO2 emissions to rise in 2017 and 2018.
  • Rising global GDP, together with the proliferation of online commerce and rapid (i.e. same-day and next-day) delivery, which continues to raise road freight demand.

Transport sector CO2 emissions by mode in the Sustainable Development Scenario, 2000-2030


Global transport sector energy intensity (total energy consumption per unit of GDP) dropped by 2.1% in 2018 after falling an average 1.5% per year between 2000 and 2017. However, to put transport efficiency on track with the SDS, energy intensity must drop by 3.4% on average annually from 2019 to 2030 – more than double the annual average rate of decrease since 2000.

For the transport sector to meet projected mobility and freight demand while reversing CO2 emissions growth, energy efficiency measures will need to be deployed to maximum effect.

Energy efficiency measures in transport can take many forms, including: managing travel demand to reduce frequency and distance, as well as dependence on high-energy-intensity modes (e.g. car and air); shifting travel to the most efficient modes; system-level and operational efficiency measures; and deploying energy-efficient technologies for vehicles and the fuels that drive them (e.g. electrification enables the use of motors that are far more efficient than internal combustion engines).

Transport sector energy intensity in the Sustainable Development Scenario, 2000-2030


An integrated, coherent and co‑ordinated set of policies is required to put the transport sector on the SDS pathway. Measures at various levels of jurisdiction – within multi-country regional blocs, at national and subnational levels, and within cities – must spur progress in:

  • Managing travel demand to reduce the frequency of trips, distances travelled, and dependence on cars, and to shift travel to the most efficient modes (i.e. the ‘avoid/shift’ approach).
  • Improving the energy efficiency (i.e. fuel economy) of vehicles.
  • Increasing the availability and use of sustainable, low-carbon fuels.

In addition to CO2 emissions, the SDS targets air quality improvements. Adopting cleaner fuels and enacting tighter emissions control standards for vehicles would improve outdoor air quality in the developed and developing world alike.

Many regulatory measures – including vehicle efficiency standards, zero-emission vehicle mandates and low-carbon fuel standards – can encourage adoption of more sustainable transport technologies.

For example, fuel economy standards have already proven their efficacy in reducing specific (per-kilometre) emissions of cars and trucks. For vehicle efficiency standards to remain effective, however, it will be critical that they evolve to:

  • Reflect real-world operations. As the Dieselgate scandal so vividly demonstrated, it is possible for car manufacturers to comply with tests even as vehicles emit pollutants with serious health impacts. The same goes for CO2 emissions, but regulatory procedures can be improved, for instance through adoption of the WLTP, a testing system that incorporates real driving emissions, and in the case of local air pollutants, through efforts like the Real Urban Emissions (TRUE) initiative, which monitors in-use emissions.
  • Broaden the regulatory scope beyond direct tailpipe emissions. Regulations should also cover the upstream emissions and sustainability impacts of fuel production and distribution. A 'well-to-wheels' approach should be adopted as new technologies such as electric and hydrogen vehicles, and alternative fuels such as biofuels, gain market shares. Policies should eventually extend beyond operations to vehicle production and disposal. While there are many practical challenges to this 'life-cycle' vehicle regulation approach (including overlap with policies covering other sectors), it is necessary to begin by gathering and analysing data to monitor the life-cycle impacts of current regulatory frameworks.
  • Align standards with climate pledges. The disparity between policy coverage and stringency and the actions needed to meet emissions reduction goals is a major obstacle in curbing transport emissions growth. To be realistic and actionable, Nationally Determined Contributions must be founded on credible projections of transport activity and include policies to promote sustainable transport.
  • Guard against regulatory loopholes and expand to encompass new technologies and business models. For example, one regulatory loophole could be closed by including trailer efficiency mandates in heavy-duty-vehicle efficiency standards, or even mandating vehicle efficiency standards for 2-wheelers (only China has such standards). Examples of regulating new business models include new ways to promote Mobility-as-a-Service, and fleet regulations for taxis and ride-sourcing platforms.

Fiscal policies can spur progress in both reducing emissions and raising air quality. Taxes that reflect the societal and environmental damage costs incurred by burning fuel influence passenger and freight mobility choices. People may reduce discretionary car trips or car-pool, purchase more efficient vehicles and drive more efficiently, choose alternative transport modes or not take trips at all. Reducing or phasing out subsidies (implicit or explicit) on transport fuels also impels these shifts.

Taxing at the point of vehicle purchase and/or circulation can also affect transport decisions. Differentiated taxation schemes, also known as 'feebates', can incentivise vehicle makers to provide more efficient technologies and consumers to purchase cleaner, more fuel-efficient cars. Ideally, taxation schemes should directly target performance outcomes, including COor local pollutant emissions reductions.

With rising efficiency and more electric vehicles in circulation, eventually fuel taxes will not provide enough revenue for road infrastructure maintenance. Although electric vehicles do not emit local air pollutants, their societal impacts include congestion and road wear. A well-timed phase-in of road pricing to supplement fuel taxation will be needed to manage the transition to cleaner and more sustainable road transport.

Transport technologies

The number of electric light-duty vehicles on the road has exceeded 5 million. Along with rising market uptake of electric cars, lower cost and better battery performance are making electrification of trucks and buses attractive for certain operations, especially in cities.

Meanwhile, China leads the world in urban train and high-speed rail expansion, with a significant amount of track laid rapidly in the past decade to supply electric, low-carbon passenger services for decades to come.

Reducing transport CO2 and pollutant emissions will require sustained policy efforts to enhance efficiency and electrification. Priorities also include anticipating and managing demand by steering new mobility developments in cities and long-term technology and policy visions for the hard-to-abate aviation, shipping and road freight subsectors.

Electric car market share in the Sustainable Development Scenario, 2000-2030


Electric vehicles

2018 was another record-breaking year for global electric car sales (1.98 million), raising total global stock to 5.12 million. Sales increased 68% in 2018, more than twice the average year-on-year sales growth required to meet the SDS level by 2030. China was the world's largest market (just over 1 million electric cars sold in 2018), followed by Europe (385 000) and the United States (361 000); the three regions made up over 90% of all sales in 2018. Norway continues to have the highest market share for sales (46% in 2018), followed by Iceland (17%) and Sweden (8%). Progress in decarbonising the power sector will accelerate the CO2 emission reduction benefits of electric vehicles.

Energy intensity of passenger transport modes, 2018



Rail is one of the most energy-efficient transport modes, accounting for 8% of global motorised passenger movements and 7% of freight but only 2% of transport energy use. Urban and high-speed rail infrastructures have scaled up rapidly over the past decade, laying the foundation for convenient, low-emissions transport within and between cities. China is leading the way with unprecedented expansion in high-speed rail: passenger activity grew nearly 20% in 2018, more than twice as fast as domestic aviation. Further rail investments in India and South East Asia in particular can help get the transport sector on track with the SDS by displacing more intensive modes such as cars, trucks and airplanes and reducing net energy use and emissions.

Average new global fuel economy of light-duty vehicles, 2006-2017, and GFEI 2030 target


Fuel economy of cars and vans

Average fuel consumption of light-duty vehicles (LDVs) improved by only 0.7% in 2017 slowing from the 2005-16 rate of 1.8% per year. To get on track with the SDS, which is aligned with the Global Fuel Economy Initiative (GFEI) 2030 targets, an annual improvement of 3.7% is needed. It is vital that standards become significantly more stringent and that vehicles comply with them in real-world driving conditions. Hopeful signs include ambitious but achievable CO2 standards passed in the EU and a proposal for stricter standards in China. Rapid adoption of electric vehicles (EVs) will also help achieve efficiency goals.

CO2 emissions from heavy-duty vehicles in the Sustainable Development Scenario, 2000-2030


Trucks and buses

Emissions from trucks and buses (heavy-duty vehicles) have risen at a rate of 2.2% annually since 2000. While policy coverage for heavy-duty vehicles (HDVs) still lags behind that of light-duty vehicles (LDVs), policy momentum has been growing. With new policies adopted in India in 2018, and in the EU expected in July 2019, more than half of HDVs sold worldwide will be covered by fuel economy and CO2 emissions standards. To achieve the SDS, more countries must adopt standards, and existing ones must become more comprehensive and stringent. In urban settings, rapid electrification (especially of buses, but increasingly of light commercial and medium-duty trucks) will help.

Global biofuel production 2010-2024 compared to consumption in the Sustainable Development Scenario


Transport biofuels

Transport biofuel production expanded 7% year-on-year in 2018, and 3% annual production growth is expected over the next five years. This falls short of the sustained 10% output growth per year needed until 2030 to align with the SDS. Stronger policy support and innovation to reduce costs are required to scale up both advanced biofuel consumption and the adoption of biofuels in aviation and marine transport, as envisaged in the SDS. As only sustainable biofuels have a place in the SDS, more widespread sustainability governance must complement higher biofuel output.

Energy intensity of international aviation in the Sustainable Development Scenario, 2000-2030



CO2 emissions from aviation continue to rise, and accounted for around 2.5% of global energy-related CO2 emissions in 2018. While energy efficiency in aviation improved by 3.2% per year between 2000 and 2014, it slowed to less than 1% per year between 2014 and 2016. In the SDS, aviation energy efficiency needs to improve by more than 3% per year to 2040. With global aviation activity continuing to grow rapidly (+140% since 2000), further international policy measures, such as more stringent carbon pricing and efficiency standards, could help put aviation on the SDS pathway.

CO2 emissions from international shipping in the Sustainable Development Scenario, 2000-2050


International shipping

In April 2018, the International Maritime Organization (IMO) agreed to reduce GHG emissions by at least 50% by 2050 compared with a 2008 baseline, with carbon intensity reduction targets for 2030 and 2050. This historical milestone will need to be quickly followed by dedicated polices and other measures. Because of the large price gap between conventional and clean energy technologies, ambitious and timely measures enabling strong efficiency improvements and rapid fuel switching to low-carbon fuels are vital.