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Tracking Transport 2021

Not on track
Robert Ruggiero 3ci1ysp1e7w Unsplash

About this report

CO2 emissions from the global transport sector fell by over 10% in 2020, as Covid-19-related restrictions and lockdowns altered personal mobility patterns, global supply chains and domestic and international travel. Global transport emissions were 7.2 Gt CO2 in 2020, down from nearly 8.5 Gt in 2019.

Transport demand in 2021 is rebounding, with demand for passenger and cargo transport expected to continue increasing rapidly. Even with anticipated growth in transport demand, the Net Zero Emissions by 2050 Scenario requires transport sector emissions to fall by 20% to 5.7 Gt by 2030. Achieving this drop would depend on policies to encourage modal shifts to the least carbon-intensive travel options, and operational and technical energy efficiency measures to reduce the carbon intensity of all transport modes.

In rail and road, stronger policies are needed to accelerate the establishment of infrastructure to support zero-emissions vehicles. Policies that promote the blending of true low-carbon fuels are critical to decarbonise aviation, shipping and heavy-duty road freight.

Global CO2 emissions from transport by subsector, 2000-2030

Tracking progress

Transforming the transport sector to place it on the Net Zero pathway will require a range of government decisions over the next decade. Policy efforts across all transport modes must be deepened and extended without delay, and it will be essential to expand international co-operation. 

CO2 emissions from aviation and shipping have been rising rapidly in the past two decades, along with those from the road subsector, which accounts for about 75% of transport demand and emissions today. However, the Covid-19 pandemic halted passenger and commercial vehicle travel and sales abruptly and caused aviation, rail and maritime shipping activity to plummet. 

Although the different transport subsectors are recovering at varying speeds, vehicle sales were already rebounding in 2020 in countries where lockdowns had begun to ease. Road transport activity is therefore expected to recover to pre-Covid-19 levels in the last months of 2021, with CO2 emissions on track to be just 5% below the 2019 level in 2021.  

While global aviation passenger numbers are expected to return to 2019 levels only in 2023 (at the earliest), demand is projected to grow over the next decades, and air cargo traffic already exceeded pre-crisis levels by nearly 10% in May 2021. Furthermore, although major uncertainties remain, global seaborne trade is anticipated to surpass the 2019 level by 0.5% in 2021. 

As transport activity rebounds and continues to grow, targeted policies will be needed to stem rising CO2 emissions. Under the Net Zero Emissions Scenario, direct CO2 emissions from fossil fuel use by 2/3-wheelers and light-duty vehicles decrease 2% and 5% per year on average by 2030, respectively. In light of a higher concentration of zero emission technologies still under development in the heavy trucks, shipping and aviation sectors, collectively CO2 emissions decrease only 0.5% per year on average between 2020 and 2030. As these technologies become commercially available, the average annual decrease reaches 8.5% per year from 2030 to 2050 in the Net Zero Emissions Scenario.

Road transport electrification continues to expand: globally, the number of electric cars on the road reached 10 million in 2020 (a 1% stock share), the electric truck stock exceeded 30 000 units, and electric bus registrations are on the rise. At the same time, a shift towards SUVs and larger vehicles has stalled fuel consumption and CO2 emissions reductions of new light-duty vehicles sold globally.  

While the carbon intensity of commercial passenger aircraft has fallen more than 70% in the last 60 years, progress in aircraft efficiency has slowed. Similarly, although the global maritime fleet has become more energy-efficient, efficiency improvements spurred by current short-term measures fall short of Net Zero Scenario requirements. 

To meet this scenario’s energy efficiency milestones and emissions trajectory, stringent fuel economy standards as well as government policies and corporate commitments will need to ensure that no new internal combustion engine vehicles are sold by 2035, and that electric vehicles make up 20% of the vehicle stock by 2030. Additionally, the fuel economy of heavy road vehicles must improve continuously, with electric and fuel cell vehicles making up 30% of heavy trucks sold in 2030. 

In the short term, accelerating various efficiency improvements in aviation and shipping can be especially important to reduce the carbon intensity of these subsectors with hard-to-abate emissions.

Global carbon intensity by mode in the Announced Pledges and the Net Zero scenarios, 2020-2030


In the wake of the Covid-19 pandemic, global use of public transit fell by 50 to 90% and rail by 80%. In contrast, the pandemic triggered a resurgence in active modes of transport (i.e. walking and cycling) and micromobility. The longevity of these trends remains unclear, but certainly alignment with the Net Zero Scenario will require a sustained modal shift from car trips to active and public travel – as well as from air travel to rail. In the Net Zero Scenario, 20-50% of car trips are shifted to buses (depending on the city), with additional trips replaced by cycling, walking and other public transport. By the mid-2030s, this leads to a reduction in emissions from cars of more than 320 Mt CO2.  

In response to the pandemic, a number of cities (MilanParisBarcelona and others) have reallocated road space to allow increased active travel, and rail companies have been offering more night trains as an alternative to flying. To align with the Net Zero pathway, policy efforts should continue to take advantage of disruptions in mobility routines to promote lasting behavioural change. 

Many of the fuels and technologies that offer potential for long-term decarbonisation of transport modes for which emissions abatement is challenging tend to be in the very early stages of development. In road transport, the range of zero-emission heavy-duty vehicle models continues to expand, but experiments in high-pressure, high-throughput hydrogen refuelling and charging options for heavy freight trucks tend to be treated as proof-of-concept activities only.  

Breakthroughs in battery chemistry are needed to enable short- and medium-haul battery electric passenger aircraft development, as lithium-sulphur and lithium-air batteries that have the durability and energy density needed power short-haul flights are still in the research phase. Similarly, ship engines capable of running on ammonia are still at the prototype stage, yet ammonia is projected to play a major role in transoceanic journeys in the Net Zero Scenario. 

To get on the Net Zero pathway, governments need to quickly define clear strategies and R&D priorities by 2025 at the latest. Such strategies should be informed by international collaboration and dialogue.

Reducing transport CO2 and pollutant emissions will require sustained policy efforts to enhance efficiency and electrification across all transport modes, particularly road and rail. Priorities also include anticipating and managing demand by shaping new mobility developments in cities and by formulating long-term technology and policy visions for the heavy-duty subsectors such as road freight, shipping, and aviation. 

Aligning the transport sector with Net Zero modelling will require a co-ordinated policy approach that facilitates decarbonisation across all transport modes and expands supporting infrastructure. Measures at various levels of jurisdiction – national, subnational, within cities and in multi-country regional blocs – must support progress in: 

  • Defining clear R&D priorities for all transport technologies.  
  • Improving the fuel economy of all transport modes. 
  • Stimulating the uptake of zero-emission vehicles 
  • Increasing the availability and use of sustainable low-carbon fuels across the entire sector. 
  • Managing travel demand, distances travelled and car dependence; sustaining active modes of travel; and supporting public transit recovery. 

Future policy measures should also be shaped by lessons learnt from the pandemic, with governments particularly addressing how they can support transport sector employment while also improving resilience and sustainability

In countries where high fuel taxes are levied, light-duty vehicle fuel consumption (measured in litres of fuel consumed per vehicle-kilometre) is among the lowest in the world. Other fiscal measures, including elevated taxation of large, heavy vehicles and/or lower taxation of small, light-weight vehicles can accelerate fuel economy improvements. 

Measures such as congestion charges, parking fees, road pricing and tolls can encourage a shift towards rail, public and active transport modes by reducing the appeal of private vehicle use.  

In subsectors with hard-to-abate emissions, such as aviation, shipping and trucking, carbon pricing or tax schemes can raise the appeal of alternative fuels, which are critical for decarbonisation in these areas. By passing carbon costs on to air passengers, carbon pricing can make high-speed rail more attractive for long-distance travel. 

Before the pandemic, a number of countries had already strengthened their standards for CO2 emissions and fuel economy, as well as their EV purchase subsidies. These measures helped shield electric vehicle sales from the impacts of the pandemic. Now, to maintain momentum and accelerate road transport electrification in line with Net Zero Emissions Scenario, countries must continue to implement and tighten such regulatory measures. Relaxation of policies for short-term economic exigencies must be prevented. 

In maritime shipping, operational carbon intensity standards must be tightened immediately to facilitate decarbonisation and enhance the competitiveness of zero- and low-carbon fuels. Low-carbon fuel standards and blending mandates, as well as offtake agreements to purchase biogenically derived or synthetic (power-to-liquid) alternatives to fossil jet kerosene can play an important role in steering investment towards R&D and demonstration of sustainable aviation fuels.

Fifty-six percent of the globe’s population lived in cities and towns in 2020. With urbanisation on the rise, cities should take advantage of various transport strategies now to induce modal shifts and travel reductions in line with the Net Zero Scenario.  

  • The resurgence in active modes of transport has provided governments a policy window to improve and expand infrastructure (e.g. bicycle lanes and car-free zones), and make road reallocation permanent.  
  • Transit-oriented development that integrates high-density living with urban rail should be promoted to achieve high passenger throughput on urban rail networks. Bus networks as well as walking, cycling and other last-mile solutions could be connected. 

Cities can also employ measures to stem the uptake of larger, less fuel-efficient vehicles, including allocating a greater share of parking spaces to smaller cars, and/or basing parking fees on vehicle size.