Are Cars a Key Factor in Climate Change? Research, Legislation and Life Cycle Assessment

There is increasing scientific evidence that anthropogenic climate change is real and threatens our planet and lifestyles in many ways. According to The US Environmental Protection Agency (US EPA), scientists are fully aware that human activities are changing the composition of Earth's atmosphere and increasing greenhouse gas (GHG) concentrations tend to warm the planet.

According to the U.N. Framework Convention on Climate Change (UNFCCC), transport remains a sector where emission reductions are required urgently but are difficult to achieve. Emissions from transportation grew by 23.9 % from 1990 to 2004.”

Cars are a significant source of GHG emissions. Tailpipe emissions of light duty vehicles alone will account for 10% of global CO2 emissions. Legislators worldwide are addressing this challenge by setting progressive automotive GHG emission limits, fuel economy standards or a combination of both.

A Hole in the Tailpipe Regulations

All major present legislation is focused on tailpipe or use-phase emissions. The GHG emissions caused mainly by the combustion of fuels are considered by Tailpipe. Use-phase focuses on emissions from the complete fuel cycle, both production and consumption of fuel. For a normal gasoline-powered vehicle roughly 85% of GHG emissions come from the fuel cycle with remaining 15% caused by vehicle production and disposal.

A high fuel economy brings down fuel cycle emissions and one important way to achieve this is by reducing vehicle mass. The automobile industry is under considerable pressure to light-weight vehicles in order to meet GHG emission standards in Europe and Canada, fuel economy standards in Japan and China, and a mix of both in the U.S. and South Korea. Even though one should commend policy makers for their resolve, all present regulatory approaches are challenging for the reason of the possibility of unintended consequences.

The Possibility of Unintended Consequences

The regulation of only tailpipe or use phase emissions may result in industry responses that actually make things worse. For example the use of light-weight materials to reduce vehicle mass decreases use-phase emissions but as the production of light-weight materials is typically GHG intensive, the emissions during vehicle production are likely to increase significantly. In case the increase in production emissions is more than the decrease in use-phase emissions, vehicle light-weighting actually increases total emissions, which is an unintended consequence.

Vehicle light-weighting is also expensive as it relies typically on expensive materials and requires retooling of manufacturing lines. There is evidence that the redesigning of power trains offers a better environmental return on investment than light-weighting.

If emissions from vehicle production are ignored the problems created will be further aggravated by future low-carbon fuels and drive-train technologies. While a typical gasoline-powered vehicle currently emits only around 15% of its GHG during production, using cellulosic ethanol or shifting towards battery or hybrid electric vehicles will drastically increase the share of vehicle production emissions. For a battery electric vehicle completely powered by renewable electricity, vehicle production emissions could account for as much as 85% - a complete reversal of the present figures.

In order to ensure total reduction in automotive GHG emissions, fuel economy or tailpipe emission standards are not sufficient. Unintended Consequences are more common than one may imagine. Certain examples are given below:

Case Study 1

Corporate action: In the 1920s, tetra-ethyl lead (TEL) started being used as anti-knock, which enabled the design of more powerful and fuel-efficient engines.

Unintended consequence: Catastrophic levels of atmospheric lead pollution.

Public policy response: Ban leaded automotive fuels.

Case Study 2

Corporate Action: In the 1930s, chlorofluorocarbons (CFCs) started being used as non-toxic, non-reactive alternatives to toxic and flammable refrigerants and propellants, such as ammonia, chloromethane, and sulfur dioxide.

Unintended consequence: Dramatic depletion of the stratospheric ozone layer.

Public Policy Response: Phase out CFCs through the Montreal Protocol.

Case Study 3

Public Policy Decision: In 2005 the USA created a Renewable Fuel Standard (RFS) as part of its Energy Policy Act (EPAct).

Potential unintended consequence: In certain cases biofuel production and use might have higher fossil energy demand and GHG emissions than fossil fuels.

Avoiding Unintended Consequences with Life Cycle Assessment (LCA)

A comprehensive way of measuring automotive GHG emissions is by using life cycle assessment (LCA), which takes into account all of the emissions created during the life of a product from raw material production to product end-of-life. It is only when a vehicle’s total life-cycle emissions are accounted for can the net environmental impact of different designs be compared. The production of lightweight materials like magnesium, aluminium and carbon fiber are typically GHG-intensive and may offset or even outweigh the emission savings due to fuel economy improvements.

How Widespread and Accepted is LCA?

Since the early 1970s, LCA methodology and practice have been developing. It is presently a mature assessment tool with global standards. Independent of legislation, many car manufacturers are already using life cycle thinking and LCA, recognizing its importance and effectiveness in product and process design.

  • In 2002, Honda implemented LCA Data and Management Systems as it regards LCA as a vital tool for environmental impact assessment.
  • Toyota actively carries out LCA in the development stage of new technology and has decided not to use carbon fiber because the high GHG emissions released during its production outweigh the GHG savings from mass reduction.
  • Volkswagen and Mercedes make use of LCA for environmental product design and issue environmental certificates or commendations based on the relevant ISO-standards.
  • Ford uses LCA routinely and has begun to require carbon footprint data from its suppliers.
  • The 2010 green initiative from Nissan incorporates LCA for all new models.
  • AIAG (Automotive Industry Action Group) has developed carbon footprinting requirements in the automotive industry as part of its supply chain objectives.
  • Ricardo recently published a study emphasizing the shortcomings of regulating tailpipe CO2 and the importance of LCA in determining automotive GHG emissions.

Material producers equally accept and use LCA. Actually along with many of their member companies, the trade associations of the steel, aluminium, and plastic industries are among the most active members of the global LCA community.


Several environmental agencies around the world support life cycle assessment, including the European Commission which calls it the best framework for assessing the potential environmental impacts of products currently available.

Environmental regulators and policy makers have begun to draft legislation with a life cycle perspective, such as California’s Low Carbon Fuel Standard, but need to do so more frequently and consistently. Life-cycle-based environmental regulation is in its initial fancy and not without significant challenges. Nevertheless, the regulation of automotive GHG emissions provides a unique opportunity to align regulatory practice with the state of the art in environmental product policy and launch a new area of enlightened and successful environmental legislation.

This information has been sourced, reviewed and adapted from materials provided by WorldAutoSteel (World Auto Steel).

For more information on this source, please visit WorldAutoSteel (World Auto Steel).


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