Transport is a significant contributor to global carbon dioxide (CO2) emissions, accounting for approximately one-fifth of the total worldwide emissions. When focusing solely on CO2 emissions derived from energy consumption, this sector represents an even larger share, around 24%. Among the various modes of transportation, cars play a crucial role in this environmental impact.
To understand the breakdown of these emissions, it’s essential to analyze the contributions from different transport methods such as cars, trucks, airplanes, and trains.
The data presented in the chart below, sourced from the International Energy Agency (IEA), illustrates the distribution of global transport emissions in 2018.
Global CO2 emissions from transport in 2018, broken down by transport mode. Passenger vehicles, including cars and buses, are the largest contributors.
Road travel is the dominant source of emissions within the transport sector, responsible for three-quarters of the total. Passenger vehicles, specifically cars and buses, are the largest component of road travel emissions, contributing 45.1%. Freight transport by trucks makes up the remaining 29.4% of road transport emissions.
Considering that the entire transport sector contributes 21% of global CO2 emissions, and road transport constitutes three-fourths of this, it can be concluded that road transport, heavily influenced by Transport Cars, is responsible for approximately 15% of total global CO2 emissions. This highlights the substantial environmental footprint of cars in the broader context of transport emissions.
While air travel often receives considerable attention in discussions about climate change action, it accounts for a smaller portion of transport emissions, at 11.6%. Aviation emits nearly one billion tonnes of CO2 annually, representing about 2.5% of total global emissions. International shipping contributes a comparable amount, at 10.6%.
In contrast, rail travel and freight produce minimal emissions, accounting for only 1% of transport emissions. Other forms of transport, primarily involving the movement of materials like water, oil, and gas through pipelines, are responsible for 2.2%.
The Future of Transport Cars and Decarbonization
Looking ahead, global transport demand is projected to increase significantly in the coming decades. This growth is driven by factors such as population increase, rising incomes, and greater affordability of personal transport like cars, as well as increased air travel and train usage. The IEA’s “Energy Technology Perspectives” report anticipates a doubling of global transport activity (measured in passenger kilometers), a 60% rise in car ownership rates, and a tripling of demand for both passenger and freight aviation by 2070. Without significant changes, these trends would lead to a substantial surge in transport-related emissions, with transport cars continuing to be a major factor.
However, technological advancements, particularly in the realm of electric vehicles (EVs), offer a pathway to mitigate this increase. As global electricity generation shifts towards lower-carbon sources, the adoption of electric cars presents a viable strategy to reduce emissions from passenger transport and reshape the impact of transport cars on the environment.
The IEA’s “Sustainable Development Scenario,” detailed in its Energy Technology Perspective report, provides an optimistic outlook for achieving net-zero CO2 emissions from the global energy sector by 2070. This scenario outlines potential decarbonization pathways for various segments within the transport sector.
This visualization from the IEA report shows projected reductions in CO2 emissions from transport under the Sustainable Development Scenario, highlighting the potential for significant decarbonization across different transport modes.
Global CO2 emissions from transport in 2018, broken down by transport mode. Passenger vehicles, including cars and buses, are the largest contributors.
The IEA scenario suggests that some transport sub-sectors can achieve decarbonization within the coming decades through electrification and hydrogen technologies. It projects a phase-out of emissions from motorcycles by 2040, rail by 2050, and small trucks by 2060. While complete elimination of emissions from cars and buses is projected by 2070, the scenario anticipates that major economies, including the European Union, the United States, China, and Japan, will have largely phased out conventional vehicles as early as 2040, transitioning significantly towards electric transport cars and buses.
Despite these advancements, decarbonizing certain transport sectors remains a significant challenge. Research published in “Science” by Steven Davis and colleagues identifies long-distance road freight (large trucks), aviation, and shipping as particularly difficult to decarbonize. The practical application of hydrogen or batteries as primary power sources for planes, ships, and large trucks is limited due to range and power requirements. The size and weight of current battery technology or hydrogen fuel tanks are considerably greater than traditional combustion engines, posing significant engineering and logistical hurdles.
Consequently, even with substantial reductions as visualized in the IEA scenario, emissions from these harder-to-decarbonize sectors could position transport as the largest contributor to energy-related emissions by 2070. Achieving net-zero emissions across the entire energy sector will necessitate offsetting these remaining emissions through ‘negative emissions’ technologies, such as carbon capture and storage from bioenergy or direct air capture from other segments of the energy system.
The IEA estimates that nearly two-thirds of the emissions reductions required to reach net-zero rely on technologies that are not yet commercially viable at scale. This underscores the IEA’s assessment that “Reducing CO2 emissions in the transport sector over the next half-century will be a formidable task,” especially when considering the continued reliance on transport cars globally and the need for a rapid transition to sustainable alternatives.
References
[1] – Note 1 from original article
[2] – Note 2 from original article
[3] – Note 3 from original article
[4] – Note 4 from original article
Cite this work
Hannah Ritchie (2020) – “Cars, planes, trains: where do CO₂ emissions from transport come from?” Published online at OurWorldinData.org. Retrieved from: ‘https://ourworldindata.org/co2-emissions-from-transport’ [Online Resource]
BibTeX citation
@article{owid-co2-emissions-from-transport, author = {Hannah Ritchie}, title = {Cars, planes, trains: where do CO₂ emissions from transport come from?}, journal = {Our World in Data}, year = {2020}, note = {https://ourworldindata.org/co2-emissions-from-transport} }
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