Climate change, air pollution and the contribution of fossil-fuelled motorised road transport

Key facts

  • Estimates suggest that the global car fleet will triple in size between 2010 and 2050 [1];
  • In Britain, vehicle miles travelled by motorised vehicles rose from 304 billion in 2013 to 320 billion in 2016; a rise of 5% in just three years [2];
  • About a quarter of all energy-related CO2 emissions from fuel combustion in the UK come from transport [3];
  • Globally, CO2 emissions from transport grew by 71% between 1990 and 2014 [4];
  • In the UK, outdoor air pollution causes an estimated 40,000 premature deaths every year [5].

Background

Fossil-fuelled motorised road transport (diesel and petrol vehicles), which comprise the vast majority of motorised road transport, is a significant contributor to climate change due to the release of CO2 and other greenhouse gases in exhaust emissions.

Diesel and petrol vehicle exhaust emissions also contribute to air pollution, causing premature death from respiratory disease.

The process of manufacture of vehicles also contributes to climate change and air pollution.   

The battle to combat CO2 emissions and air pollution resulting from motorised road transport is a battle against a rising tide. The Global Fuel Economy Initiative estimates the global fleet of cars alone will triple between 2010 and 2050 [6]. Such projections are based on a number of factors, including a continued rise in the number of people on the planet [7], road building, affordable vehicles and affordable petrol and diesel. 

Growth in motorised road transport is occurring fastest in many low and middle income countries but also happening in the richest nations. In Britain, vehicle miles travelled by motorised vehicles rose from 304 billion in 2013 to 320 billion in 2016; a rise of 5% in just three years, with notable rises in miles travelled by vans and miles travelled on the Strategic Road Network (motorways and main A roads, which are being extended and upgraded) [8].  

Numbers of licensed vehicles in Britain is also on the rise. For example, there were 25.8 million licensed cars in the third quarter of 2015 compared with 25.2 million in the same period of 2014 – an extra half a million cars in one year – with the largest increases happening in the south east of England [9].

Climate change and the contribution of road transport

In 2016 the Paris Agreement committed countries within the UN’s Framework Convention on Climate Change to “ambitious efforts” to achieve a limit in temperature rise to below 2°C. Countries must submit a report of intended contributions (Nationally Determined Contributions (NDCs)). [10]

The International Energy Agency (IEA) has calculated that, despite projected increasing demand, greenhouse gas emissions from the energy sector (inclusive of transport) need to start falling by 2020 if there is to be a reasonable chance of limiting temperature rise to below 2°C [11].

As a current member of the EU, the UK is signed up to the EU’s NDC, which commits to a 40% reduction in domestic greenhouse gas emissions below 1990 levels by 2030 [12].  The UK’s Climate Change Act 2008 legally commits the government to reduce its greenhouse gas emissions by 80% by 2050 [13].  

About a quarter of all energy-related CO2 emissions from fuel combustion in the UK come from transport [14]. (This figure is the same worldwide [15].)The majority (three-quarters) of global CO2 emissions from transport are emitted by road transport. [16]

The amount of CO2 emissions from transport has grown significantly in recent years. Globally, CO2 emissions from transport grew by 71% between 1990 and 2014 [17],

There are other greenhouse gases emitted from diesel and petrol-fuelled vehicle exhaust emissions, notably nitrogen oxides (NOx).

The process of obtaining and refining diesel and petrol also releases greenhouse gases.

Fossil-fuelled road transport also releases soot. Black carbon is the light-absorbing component of small particles that make up soot, and is considered the second biggest contributor to climate change. Because it is dark in colour, black carbon absorbs solar energy, warms the climate and causes weather changes. When deposited on arctic snow, it decreases the planet’s ability to reflect the sun [18], hastening ice melt [19]. Road vehicles contribute globally 9% of black carbon emissions, with nearly all from diesel vehicles [20]. 

Air pollution and respiratory disease caused by road transport

Exhaust emissions from fossil-fuelled road transport contributes significantly to outdoor air pollution, which contributes to premature deaths from respiratory conditions, particularly in clogged cities.

The Gothenburg Protocol commits countries, including the UK as part of the EU, to reduce levels of air pollution by 2020 to targets [21]., The UK, along with all other EU states, is also required to comply with EC directives on air quality standards [22]. However, many countries including the UK are failing to comply. In November 2016, in a case brought by the charity ClientEarth, the UK government was found guilty in the High Court of not implementing measures that would tackle air pollution [23].

Health-damaging pollutants include nitrogen oxides and particulates.

Nitrogen oxides are a family of poisonous gases referred to as NOx. NOx damages lung function triggering asthma and contributing to lung disease.

Particulates are small particles, with the most dangerous ones being too small to see. They enter into lungs or blood causing lung disease including cancer [24] [25]. Course particles known as PM10 (between 2.5 microns and 10 microns in diameter) can lodge in the upper throat and airways to the lungs. Fine particles known as PM2.5 (between 0.1 microns and 2.5 microns) are invisible and can reach all the way down to lungs' alveoli (tiny spaces in lungs that allow oxygen to move into blood). (Black carbon is also a component of these sized particles.) Ultra-fine particles (below 0.1 microns) can penetrate blood.

The level and ratios of NOx, particulates, and black carbon emitted per vehicle varies. Older vehicles are often much worse than newer vehicles. Diesel vehicles are often much worse than petrol vehicles. It has emerged in recent years that diesel vehicles are emitting far more pollution when on the road than in tests they are required to pass to meet regulatory standards. This is due to a number of factors including for example hot weather, but also due to some manufacturers fitting ‘cheat’ or ‘defeat’ devices that enabled higher emissions on the road [26]. This has significantly hampered efforts by legislators to tackle pollution through vehicle exhaust emission regulation.

Outdoor air pollution has been estimated to account for 3.1 million premature deaths globally each year from respiratory diseases such as lung cancer [27] [28]. Asian cities are notorious for being blighted by air pollution contributed to significantly by manufacturing and rising motorised traffic, with children and the elderly sometimes being advised to stay indoors or schools being temporarily shut.

In the UK, outdoor air pollution is increasingly recognised as a health hazard causing an estimated 40,000 premature deaths a year [29]; and research by MIT found the leading contributor is transport, with transport-related air pollution causing 7,500 annual premature deaths [30].

The Gothenburg Protocol requires the UK to reduce emissions of PM2.5 by 30 per cent compared to 2005 emissions by 2020, but levels are not reducing. The level for both PM10 and PM2.5 barely changed between 2009 and 2015, with emissions of both pollutants slightly higher in 2015 than in 2009. Emissions from road transport is estimated to account for 14 per cent of PM10 emissions and 13 per cent of PM2.5 in 2015 [31].

In areas of the UK where NOx levels are a cause for concern, motorised road transport is by far the biggest contributor and according to the government “presents the most significant opportunity to improve air quality”. [32]

In London, more than 800 schools are located in areas with NOx levels exceeding limits. In the first five days of 2017, London breached its European-set legal limits for levels of air pollution for the entire year [33]. Mayor Sadiq Khan described London's toxic air as a public health emergency, with London now issues warnings to people with heart or lung difficulties, to limit exertion when pollution levels are high [34].

Emissions from the manufacturing process

It should not be forgotten that the manufacture of vehicles, and the disposal of vehicles at the end of their life, also releases significant greenhouse gases and air pollutants. Vehicles are large and complex to manufacture. They require the mining, extraction, transport and manufacture of a range of materials, including metals, rubber and plastics. [35]

Vehicle manufacturing plants require a lot of power; this power still often comes from coal-fired power plants, emitting more CO2.

The process of obtaining and refining diesel and petrol also releases pollution.  


End notes

[1] Global Fuel Economy Initiative, FIA Foundation
[2] Road use statistics Great Britain 2016, Department for Transport, 2016
[3] The Carbon Plan: Delivering our low carbon future, HM Government, 2011
[4] CO2 Emissions from Fuel Combustion: highlights, International Energy Agency, 2016
[5] Every Breathe We Take: the life-long impact of air pollution, Royal College of Physicians, 2016
[6] Global Fuel Economy Initiative, FIA Foundation
[7] Global status report on road safety 2015, World Health Organisation, 2016
[8] Road use statistics Great Britain 2016, Department for Transport, 2016
[9] Vehicle Licencing Statistics: December 2016, Department for Transport, 2017, Table VEH0104
[10] Paris Agreement: Essential elements, United Nations framework convention on climate change, 2016
[11] Ibid
[12] Intended Nationally Determined Contribution of the EU and its Member States, European Commission, 2015
[13] Climate Change Act 2008, gov.uk, 2008
[14] The Carbon Plan: Delivering our low carbon future, HM Government, 2011
[15] CO2 Emissions from Fuel Combustion: highlights, International Energy Agency, 2016
[16] Ibid
[17] Ibid
[18] Black Carbon Research, United States, Energy Protection Agency, accessed: 07.03.2017
[19] Reducing Black Carbon Emissions from Diesel Vehicles: Impacts, Control Strategies, and Cost-Benefit Analysis, The World Bank, 2014
[20] Uherek, E, et al, (2010), Transport Impacts on Atmosphere and Climate: Land Transport, Atmospheric Environment 44 (37): 4772–4816
[21] The Gothenburg Protocol: Guidance documents and other methodological materials for the implementation of the 1999 Protocol to Abate Acidification, Eutrophication and Ground-level Ozone, UNECE
[22] Environment: Ambient air quality directives, European Commission, 2016 
[23] High Court Judgement on ClientEarth 2 vs SSEFA on UK Air Pollution Plans, Royal Courts of Justice, 2016
[24] Particulate matter from modern gasoline engines damages our lungs, University of Bern, 2015
[25] Health Effects of Particulate Matter: Policy implications for countries in eastern Europe, Caucuses and central Asia, World Health Organisation, 2013
[26] Franco, V, et al, Real-world exhaust emissions from diesel cars, International Council on Clean Transport, 2014
[27] Lim SS et al., A comparative risk assessment of burden of disease and injury attributable to 67 risk factors and risk factor clusters in 21 regions, 1990–2010: a systematic analysis for the Global Burden of Disease Study 2010, Lancet, 2012, 380: 2224-2260.
[28] Cohen AJ et al., Urban air pollution. In: Ezzati M et al., eds. Comparative quantification of health risks. Global and regional burden of disease attributable to selected major factors, World Health Organization, 2004, 2(17):1354–1433
[29] Every Breathe We Take: the life-long impact of air pollution, Royal College of Physicians, 2016
[30] Yim, S. & Barrett, S., Public health impacts of combustion emissions in the United Kingdom, Department of Aeronautics and Astronautics, Massachusetts Institute of Technology, Cambridge, Massachusetts, United StatesEnviron. Sci. Technol., 2012, 46 (8), pp 4291–4296
[31] Statistical Release: Emissions of air pollutants in the UK 1970 to 2015, Department for Environment, Food and Rural Affairs, 2016
[32] Improving Air Quality in the UK: Tackling nitrogen dioxide in our towns and cities UK overview document, Department for Environment, Food and Rural Affairs, 2015
[33] Pollution Graphs: Seven day graph for Lambeth Brixton Road 30 December 2016 -6 January 2017, London Air, 2017
[34] Sadiq Khan unveils action plan to battle London’s toxic air, London Assembly, 2016
[35] Statistical Release: Emissions of air pollutants in the UK 1970 to 2015, Department for Environment, Food and Rural Affairs, 2016

Date posted: March 2017