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Analyzing Global Transport Emissions

Global transport emissions

Transport has been the lifeline of human economy and society since the dawn of civilization. Given the level of global interdependence today, without the ability to move around goods and people, one could say with a reasonable degree of certainty, that the world would be pushed to the brink of collapse. But what is the environmental cost of our intense transportation demands? In 2018, global CO2 emissions from transportation (including transportation inside countries, as well as between countries, and for all purposes, including moving people and goods) resulted in a total of 8 billion metric tonnes of Carbon Dioxide released into the environment. This accounted for around one-fifth of total global anthropogenic CO2 emissions (1).

Transportation clearly has a significant ecological footprint, but how exactly is this footprint distributed across the world? The following pie chart indicates that just a few countries – identified as the highest transport-related CO2 emitters – were responsible for considerable proportions of global transport emissions in 2018. These countries include the USA, China, India, Russia, Japan, Canada, Brazil, and Germany, in descending order of proportion, and combined, were responsible for nearly half of the world’s transport-related CO2 emissions in that year. In fact, the US alone was responsible for about 21% (more than one-fifth) of these emissions, with China around half of that, at 11%, and India at 4%.

Per capita transport emissions in 2018

The countries identified have vastly different demographic structures, particularly population sizes, so it would be useful to analyze this scenario accounting for national populations, to get a clearer picture of emissions levels on a per-person basis. When transport emissions are examined through this lens, the picture changes, as seen in the following bar chart.

The bar chart includes only two of the countries identified earlier: the USA and Canada. The others, like Japan, China, and India, which do have large transport-related ecological footprints on an absolute level, do not have the highest per capita transport emissions. Instead, the per-capita emissions chart is dominated by USA and Canada, and small, rich countries or territories that are either highly developed European countries like Luxembourg, or rich Middle eastern states like Qatar, Kuwait, the United Arab Emirates and Saudi Arabia. In 2018, these identified countries emitted at least four times the global average of 1.07 tonnes of transport-related CO2 emissions per person for that year, with the highest per-capita emitter (Luxembourg) responsible for 10 tonnes of CO2 emission per person - ten times the global average.

IEA’s 2020 country report (2) for Luxembourg mentions that the country went through rapid growth over the past years and has had a large dependence on fossil fuels, which is still present today. The report also highlights that the transport sector is very emissions-intensive, stating that it accounted for more than half of all energy demand in the country. Combined with low costs of energy and the high purchasing power of consumers in the country, there has been less incentive to invest in renewables, likely explaining the growing dependence on fossil fuels and thus the explosive growth in per-capita emissions, in the environment of a rapidly growing transport sector.

The most common characteristics of the countries on this chart are high levels of GDP and economic prosperity. People from rich countries are responsible for larger transport-related emissions, as opposed to their counterparts in poorer countries. This is especially true for the US and Canada. These two countries are both, highest emitters in the absolute sense, as well as in the per capita sense. The two are also nearly identical in terms of per-capita emission; the average American and the average Canadian each were responsible for upwards of 5 tonnes of transport-related CO2 emissions in 2018, which was five times higher than the global average for that year.

Breakdown by sector of global transport emissions

It is very evident from this pie chart that road transport, with an almost three-quarter proportion, dominated the share of transport-related emissions. The second highest proportion is only 12.41%, which is aviation, followed by marine transport, which is 10.67%. This also helps explain why USA and Canada are such high per-capita emitters – car-based road transport is a major part of the lifestyle and infrastructure in these countries.

Greatest contributor to transport emissions: road transport

Historically (since 1961), road-related transport CO2 emissions have always accounted for a significant proportion of total global transport emissions. However, as shown by the following line chart, while this proportion was about 50% in 1961, it increased to 73% by 2018.

This is due to auto-centric development around the world in the second half of the 20th century; highways, roads and cars were the focus of urban and regional planning, resulting in increased road emissions. Road-related transportation emissions now account for about three-quarters of the world’s total transportation emissions. Since total transport emissions are one-fifth of all anthropogenic CO2 emissions, road transport is one of the biggest contributors to the human ecological footprint on Earth.

Per Capita transport emissions: historic trend

Analyzing the historic trend of per-capita transport emissions of some of the countries identified earlier, in the context of the changing state of transportation infrastructure, lifestyle, behavior and priorities in those countries, adds the last piece of the intricate puzzle that we have been carefully putting together. The following line chart shows that the value for global transport-related per-capita emissions has increased from 0.6 tonnes of CO2 in 1961 to 1.07 tonnes in 2018 – an increase of about 78%! Despite this notable and significant increase (especially in terms of impact on earth), it seems to not come out as the eye-catching headliner on the graph that it ought to be. Instead, it is eclipsed by the more dramatic increase exhibited in the par-capita emissions of the US and Canada, as well as by the sheer difference in magnitude of the starting values of emissions of the US (3.6 tonnes) and Canada (2.8 tonnes).

The change in India and China’s per-capita transport emissions is also not as obvious due to their overall lower values of per-capita emission. It is worthwhile to keep in mind that both countries have significant rural populations that have vastly different socioeconomic and demographic traits and undertaking a rural-urban comparison of per-capita emissions may yield a clearer picture.

In the case of the US and Canada, it is interesting to note that their respective trend-lines follow the same pattern, even converging at several points (1980, 2009, 2013, 2018). The two are clearly inextricably linked and affected by similar exogenous variables such as economic booms and recessions (for example the steep dip in 2008). This implies that more recent data (beyond 2018) will show a similar impact on the trend-lines of the two due to the economic and transportation-related ramifications of the Covid-19 global pandemic. It is curious that after the 2008 global recession, transport-related emissions stayed lowered for both countries, as compared to pre-2008 values. This is especially evident for the US, where emissions had climbed back up to 6 tonnes per person (a value seen before only in the late 1970s, right before the 1980 recession), but decreased in 2008 to around 5 tonnes, and stayed at that value even after the recession had finished and the economy started climbing back up. This calls for a more detailed analysis of transportation and transport-related emissions in the context of economic cycles. Overall, though, both the US as well as Canada, are among the highest emitters of transport-related emissions, on an absolute as well as per-capita basis.

The much-needed reduction in these emissions can only come from a major transformation in lifestyle and infrastructure, that focuses less on private car-based road transport and gravitates towards a more public (subways, trains, busses) and active-transport (bicycles, walking) based approach. The 20th century hailed the car as the savior of our transportation needs, and with the car, came the suburb. So perhaps, if we really care about the environment and our footprint on this world, we need to ponder on the inefficiencies of auto-centric living spaces and rethink our ideas about how we design our infrastructure, our cities and our communities.


All statistics and visualizations are constructed and based off data sourced from IEA, unless otherwise noted.

  1. Cars, planes, trains: where do CO2 emissions from transport come from? - Our World in Data. URL: https://ourworldindata.org/co2-emissions-from-transport
  2. Luxembourg 2020 – Analyses – IEA. URL: https://www.iea.org/reports/luxembourg-2020