Official Statistics

Transport and environment statistics 2022

Published 20 October 2022

About this release

This release presents statistics on the impact of transport on the environment, including greenhouse gas emissions from transport, and air quality. Greenhouse gas and air quality data is sourced from statistics from the Department for Business, Energy and Industrial Strategy (BEIS), and the Department for Environment, Food and Rural Affairs. Journey emission comparisons are classed as experimental statistics.

The timeline of this publication series coincides with the coronavirus (COVID-19) related restrictions. As such, figures in this release may be affected and should be interpreted with caution.

We invite feedback on the presentation and information supplied in this release, which can be emailed to the environment statistics team.

Main Findings

This publication provides estimated greenhouse gas (GHG) emissions from example journeys across the UK, based on different modes of transport. Using 2022 estimates of carbon emissions, we estimate that a petrol car journey from London to Glasgow emits approximately 4 times more CO2 equivalent (CO2e) per passenger than the equivalent journey by coach.

In 2020:

• domestic transport was responsible for emitting 99 MtCO2e (million tonnes of carbon dioxide equivalent), a 19% reduction from 2019 and the largest fall in emissions on record

• transport is the largest emitting sector of GHG emissions, producing 24% of the UK’s total emissions in 2020 (406 MtCO2e)

• emissions from international aviation fell 61% to 14.5 MtCO2e, the lowest in 30 years

• on average, 281 kilotonnes of CO2 were emitted by transport in each local authority in 2020

• 33% of Nitrogen Oxides (NOX) emissions and 14% of Particulate Matter (PM2.5) emissions came from transport

These findings coincide with COVID-19 related restrictions, which should be considered when interpreting them, particularly when making comparisons to other years.

Carbon Dioxide Equivalent (CO2e) Different greenhouse gases, such as methane and nitrogen oxides, have different impacts on the greenhouse gas effect. All gaseous emissions are converted to the amount of CO2 needed to create the same effect, and presented in this report as CO2e.

Greenhouse gases: journey emission comparisons

The following analysis presents the carbon emissions of a set of representative journeys a person in the UK might take in 2022, via a wide range of transport modes, and their consequent emissions. See below for visualisation.

Emission-releasing activity considered here includes:

• direct emissions: emissions produced by the vehicle itself

• indirect emissions: emissions produced by the extraction, refining, and transportation of the fuel used to power the vehicle. For electric vehicles, this includes the generation and transmission of electricity

• indirect effects: complex effects produced by greenhouse gases interacting with the atmosphere, for example, contrails produced by planes in the atmosphere, which reflect sunlight

Due to the complexity with regards to indirect effects, their GHG effect is uncertain and what is presented here is a central estimate. Indirect effects are only included in the calculation of air travel in our analysis, since aviation produces the largest indirect effects of all transport modes. These effects are sometimes referred to as radiative forcing, or RF.

Results

The statistical estimates developed using this method suggests that cars emit more GHGs per passenger mile than trains and coaches that convey more people, and so maximising the number of people per vehicle can reduce emissions per person. This is also why, despite planes releasing more GHGs overall than cars, by carrying more passengers, plane journeys produce emissions per capita that are comparable to car journeys.

For an example journey between London and Glasgow (see Figure 1), a journey via the average petrol car emits over 4 times more CO2e per passenger than the equivalent journey by coach, or 3.3 times more CO2e per passenger than an electric car (taking into account emissions from electricity generation and distribution).

The same journey by plane would emit over 6.8 times more CO2e per passenger than by coach, and 1.7 times more CO2e per passenger than a journey by the average petrol car.

Plane journeys that transport many passengers emit very high levels of GHGs, require passengers to make additional journeys to and from the airport, and have uncertain climatic effects beyond this (for example, the reflection of sunlight on contrails), so can produce more GHG emissions than cars. However, for our Leeds to Belfast example, car journeys must go further to reach the ferry terminal, and so cars end up emitting comparable GHG emissions to the more direct plane journey. A journey can be more efficient in terms of emissions by being more direct, which is also a reason why our example train journeys emit less overall.

Caveats

Our methodology is under continuous development to improve accuracy and utility. However, we are aware of areas where estimates will be imprecise. In general, the BEIS conversion factors rely on the construction of averages from regular travel patterns, and so individual behaviour is likely to vary from this central estimate. For example, if a car is older than average, the journey may be more polluting. If the journey encounters less traffic than average, the journey may be less polluting. Likewise, the journeys DfT have designed may not reflect every journey. For example, some journeys between the locations listed here may cover greater distances if different routes are used to avoid traffic, or refuel.

Further information, and guidance on how to develop such comparisons, can be found in the supplementary materials published alongside this report.

Figure 1: Indicative GHG emissions (KGCO2e) for a single passenger, 2022 (Table ENV0701)

Indirect Effects refers to the climatic effect of non-CO2 pollutants, such as water vapour, aerosols and nitrogen oxides. This chart reflects a central estimate of the journey’s non-CO2 effects, however this estimate is highly uncertain. Non-CO2 effects could be higher or lower.

All calculations use the BEIS conversion factors for 2022 and assume the journey is from the city centre. Trains use the national rail conversion factor which aggregates diesel and electric rail. Average engine size and 1.6 passengers assumed for diesel, electric and petrol cars. Flights assume all economy passengers and a drive via petrol car to the airport. Trams use a conversion factor shared with other metro rail networks, including some powered by non-electrified means. London buses use different conversion factors to other local buses, as they tend to have higher occupancy.

Greenhouse gas emissions from transport

In 2020, the UK produced 406 MtCO2e of GHG emissions, down 9% from 2019. Transport was responsible for 99 MtCO2e.

Between 1990 and 2019, Domestic transport emissions had decreased by 5%, from 128 to 122 MtCO2e. Between 2019 and 2020, transport emissions decreased 19%.

Overall, domestic transport emissions have decreased by 23% from 1990 to 2020, while total UK domestic emissions fell by 50% in the same period.

Figure 2: Greenhouse gas emissions by sector, 2020 (BEIS, 2022)

Transport became the largest emitting sector in 2016. This follows large decreases in energy emissions as the UK switched away from coal power and towards gas, while transport emissions have remained relatively static.

Data sources

The data we present on greenhouse gases comes from the Department for Business, Energy and Industrial Strategy GHG Inventory collected and modelled by the Ricardo Consortium (a third-party contractor). To calculate transport emissions, Ricardo combine data on fuel consumption with transport data to model emissions. It covers the period 1990 to 2020.

Transport produced 24% of the UK’s total emissions in 2020, and remains the largest emitting sector in the UK. The majority (91%) of emissions from domestic transport came from road vehicles (89 MtCO2e). The biggest contributors to this were cars and taxis, which made up 52% of the emissions from domestic transport (51 MtCO2e), Heavy Goods Vehicles (HGVs) (19% of domestic transport emissions, 18.6 MtCO2e) and vans (16% of emissions, 16 MtCO2e).

Figure 3: Greenhouse gas emissions by sector, 2020, by proportion (BEIS, 2022)

Total domestic emissions fell by 42.4 MtCO2e in 2020. This is the largest proportional fall in UK greenhouse gas emissions in a single year since the start of the data series in 1990.

Over half (55%) of the decrease in total domestic greenhouse gas emissions between 2019 and 2020 was from the reduction in emissions from transport. This fall was the largest on record, likely as a result of the COVID-19 restrictions. Prior to this, transport emissions stayed relatively static as improved fuel efficiency of most vehicles was offset by increased usage.

Of the 23.5 MtCO2e reduction in emissions from transport between 2019 and 2020, 17 MtCO2e (70%) of this came from reduced emissions from cars. This represents 40% of the reduction in total domestic emissions for the year.

This 2020 reporting period coincides with coronavirus restrictions, which will have impacted transport usage. This should be taken into consideration when making comparisons from this data.

Figure 4: Greenhouse gas emissions by transport mode, 1990 and 2020 (ENV0201)

All transport modes had lower emissions in 2020 than in 1990, with the exception of vans, which have increased their emissions by 40% in the last 30 years (see Figure 6). Despite a 10% fall in emissions since 2019, van emissions are 40% above their emissions in 1990, partly as a result of growing van ownership and operation in recent years (see Figure 6). HGVs emissions reduced by 6% from 2019 to 2020, and are down 12% since 1990.

The UK’s sixth Carbon Budget incorporated the UK’s share of international aviation and shipping emissions, to allow for these emissions to be accounted for consistently.

In 2020 international aviation made up 12% of the UK’s emissions from transport, and international shipping made up 5%.

Including international emissions shows that despite domestic emissions falling slightly prior to the pandemic, this was cancelled out by the growth in international aviation emissions. International and domestic emissions in sum increased by 10% from 1990 to 2019, and fell by 28% in 2020.

In 2019, International Aviation emissions were the highest they had ever been, 36.8 MtCO2e, more than double than in 1990. However, due to the COVID-19 pandemic, emissions plunged to 14.5 MtCO2e, 1.1 MtCO2e lower than in 1990. This is a 61% fall in emissions in one year.

International Shipping emissions have been more changeable over this period, but are 26% lower than 1990 levels, as global trade and the 2009 recession have impacted this sector.

Provisional data (BEIS, 2022) for the UK’s domestic GHG emissions from the transport sector for 2021 have been released. These estimates suggest that domestic transport carbon dioxide emissions have risen 10% (9.8 Mt), to 107.5 million tonnes in 2021. Compared to 2019, the most recent pre-pandemic year, 2021 CO2 emissions from transport remain 11.2% lower and total UK greenhouse gas emissions are 5.2% lower.

These estimates also suggest that domestic transport carbon dioxide emissions were 14% below the 1990 figure. In 2020, CO2 emissions from transport stood 22% lower than 1990.

Domestic emissions

This report primarily focuses on UK domestic GHG emissions, which does not include international aviation and shipping. Emissions are estimated following the guidance set out by the Intergovernmental Panel on Climate Change (IPCC), as required for the UK’s submissions to the United Nations Framework Convention on Climate Change (UNFCCC) each year. Under this guidance, international aviation and shipping emissions are reported but not included within the UK total. The UK Government has announced that from Carbon Budget 6 (2033 to 2037), these emissions will be counted within the UK total. This report focuses on ‘territorial’ emissions, which are those emitted within the UK’s borders. Alternative presentations, on a residency or a consumption basis, are also available (ENV0201).

Mileage and fuel use

In 2020, cars made up 76% of the road vehicle miles travelled within the UK, but produced 52% of transport emissions, while HGVs made up a much smaller proportion of the vehicle miles (6%) and their emissions were disproportionately greater (19%). This is mainly because smaller vehicles are more fuel efficient, and HGVs typically travel longer distances with greater loads.

Figure 5: Emissions and Mileage for Cars, Vans, HGVs and Buses in 2020 (tables ENV0201 and TRA0101)

Between 1990 and 2020, new vehicles have generally been more fuel efficient. As a result, emissions do not rise as fast as mileage increases.

Average new van fuel efficiency has increased in recent years because of the legislation of 2016 that ensures that all new vans must comply with Euro 6. Despite this, the large increase in van usage since 1990 has meant a proportionate rise in emissions as a result, while cars and HGVs have reduced their emissions over the same time period.

Fuel efficiency gains in HGVs have been offset by an increase in the proportion of larger, and heavier, HGVs amongst new registrations (DfT, VEH0506). In addition, new car fuel efficiency has been decreasing since 2016 after a period of growth. This is largely driven by an increase in the proportion of SUVs and other large vehicles amongst new car registrations (DfT, df_VEH0220).

Figure 6: Change in mileage and emissions, 1990 to 2020 (tables ENV0201 and TRA0101)

CO2 Emissions from transport by local authority

CO2 emissions from transport are unevenly distributed throughout the UK. Average transport emissions for a UK local authority in 2020 were 281 kilotonnnes of CO2, though Figure 5 illustrates the variation in emissions across local authorities.

High levels of emissions from transport were seen in urban areas such as Leeds and Birmingham (similar to pre-pandemic trends, despite 17% and 18% declines in transport emissions respectively), as well as rural areas like Cornwall, Midlands towns such as Buckinghamshire and West Northamptonshire and towns around the Welsh border such as Cheshire East and Cheshire West.

Figure 7: CO2 emissions from transport by local authority, 2020 (BEIS, 2022)

Between 2019 and 2020, the average transport emissions in local authorities fell by 18%. Between 2018 and 2019, before COVID-19 restrictions affected transport, there had been an average 2% decline in emissions from transport in local authorities.

Between 2019 and 2020, large reductions in transport emissions of up to 26% were seen in north Wales (Conwy and Denbighshire), and the regions west of London up to the West Midlands such as Warwick, Cherwell, Windsor and Maidenhead, and West Berkshire. This is primarily caused by the COVID-19 restrictions reducing traffic on the major roads nearby such as the M25 and M40. Of the 10 local authorities that saw the least reduction in transport emissions (11% or less), four were in Northern Ireland (Fermanagh and Omagh, Causeway Coast and Glens, Antrim and Newtownabbey and Mid Ulster), and five were in East England and Anglia, such as Brentwood in Essex, St Albans in Hertfordshire, and Huntingdonshire in Cambridgeshire.

Figure 8: Percentage change in CO2 emissions from transport, 2019-2020 (BEIS, 2022)

These data display vehicle emissions from roads, railways, inland waterways, and emissions from aircraft support vehicles. Readers should note that there is variation within local authorities, for example large motorways, which can skew overall presentation. Those emissions excluded are aviation, shipping and military transport for which there is no obvious basis for allocation to local areas.

Air pollution

Data sources

Air pollution figures for the UK are measured by the National Atmospheric Emissions Inventory (NAEI). Data here covers the period of 1990 to 2020. Unlike GHG emissions expressed as CO2e, there is no agreed way of comparing relative effects of different air pollutions. As a result, this report does not include a summed total of all air pollutants. Policies and targets to reduce air pollution are set out in the Clean Air Strategy (2019).

Transport vehicles also emit gases or other substances which don’t have a significant greenhouse gas effect, but do have significant health consequences. The most significant air pollutants from the transport sector are nitrogen oxides (NOX) and particulate matter (PM).

Transport contributed a substantial portion of these air pollutants to the UK’s domestic total: a third of nitrogen oxides, 14% of PM2.5 emissions, and 12% of PM10 emissions came from transport in 2020.

Air pollutants from transport have decreased since 1990, largely because newer vehicles emit less nitrogen oxides and methane. However, emissions are also dependent on vehicle type: NOX emissions from vans, for example, are 5,000 tonnes greater than a decade ago, while all other vehicle types have reduced their NOX emissions since 2010.

Figure 9: Nitrogen Oxides emitted by transport mode, 1990 to 2020 (table ENV0301)

Gradual reductions in NOX emissions among cars have been driven primarily by the introduction of legislative vehicle emission standards (for more detail on these standards, see table ENV302).

More recently these reductions have slowed with the exception of external shocks affecting transport, such as the COVID-19 pandemic or the 2008 to 2009 Great Recession.

This fall of 41,000 tonnes of NOX emissions from cars and taxis is greater than the fall in emissions from the rest of the decade, between 2010 and 2019, and is proportionately the largest fall on record (the fall in emissions from 2008 to 2009 was 23%).

Levels of particulate matter in the atmosphere remain high despite these improvements in air quality. PM from brake and tyre wear in 2020 is 12% above its total in 1990, despite a 18% fall from 2019 levels. Similarly, PM from road abrasion is 8% higher than in 1990, despite a 19% fall from 2019. These 2 sources together represent three-quarters of PM10 emissions from transport in 2020.

Figure 10: Air pollutants, from 1990 to 2020 (table ENV0301)

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Transport energy and environment statistics

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