Short answer: on average 13.2 kilogram carbon dioxide per day per person in 2018.

Motivation: wanted to see how man-made carbon (CO₂) emissions evolved over time, their impact on the global climate and see what it takes to reduce carbon emissions from cars.

Fossil fuels are a reliable and affordable source of energy for many applications. Unfortunately the burning of fossils causes a significant increase of carbon (CO₂ gas - carbon dioxide) in the atmosphere. This contributes to global warming since CO₂ is a non-condensing greenhouse gas that has a multiplier effect on water vapor, another potent greenhouse gas. For more information about greenhouse gasses we refer to the summary of NASA [1].

On this page we show how much CO₂ is emitted, and do so by using visualizations and data from Our World In Data [2], covering years up to 2018. We do so in four parts:

• First we show that 4 regions cause almost 60% of global carbon emissions; with significant differences if we look per person.
• Next we visualize the evolution since the 19th century till now, and do so by region and fossil fuel source. Other visualization are available in the Global Carbon Index [3].
• In the third part we visualize CO₂ fluctuations over the past century. The atmospheric CO₂ peak in the last century far exceeds natural fluctuations, and is clearly man made. We also visualize temperature anomalies at a global level and pathways to reduce climate impact from carbon emissions. The impact on the recent local climate is also visible in post-processed NASA MERRA-2 data in [6], which we summarize.
• In the last part we visualize emission of other greenhouse gasses expressed as CO₂ equivalents, as well as CO₂ emissions per sector. For cars it is nowadays easy to find CO₂ emissions expressed as gram per km. We do some math on these and see that average range of cars per person are surprisingly low if we want to maintain or reduce their carbon emission levels.

Unless otherwise mentioned, figures provided by our world in data [2] are licensed under CC BY 4.0 terms, and can be recognized by the "Our World in Data" logo.

1. CO₂ emissions ranked per region

The total CO₂ emission world-wide is estimated to be 36.6 billion tonne for 2018. Of this almost 60% is produced by China, the USA, the EU28 and india; which contain 47% of the global population. If we look at emission levels per person we see significant differences between these regions, and shown in Table 1, using data from [2][4][5]. The global CO₂ emission average is 13.2 kilogram per day per person (kg/d/p).

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2. Annual CO₂ emissions by region and source

Global CO₂ emissions from fossil fuels started in the mid 18th century. Figure 1 shows the emissions by region from then till now. Since 1950 emissions increased seven fold. Figure 2 provides a similar view by source. Coal, oil and natural gas dominate. Two other sources are cement production and gas flaring during fossil fuel production.

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3. Correlation of atmospheric CO₂ concentration and temperature, and scenarios for the 21st century

Since 1850 the atmospheric concentration of CO₂ has risen by about 40 percent to 420 parts per million (Figure 3), whereas it fluctuated between 200 and 300 ppm in the past 800 thousand years [10]. So the recent rise to over 400 ppm is likely human made by burning fossil fuels. While greenhouse gasses such as CO₂ are vital to obtain temperatures that can sustain life on earth, too much of them can lead to global warming. This is shown in Figure 4, where we see a global temperature increase correlated with the increase of carbon emissions, and with visible effects world-wide, such as melting of glaciers for example. A more detailed temperature overview for the past 40 years uses the NASA MERRA-2 data-set [6]. This data provides a more local view on climate change and the main observations are:

• In cool climates the number of heating degree days decreases significantly, which corresponds to warming of the climate.
• In warm climates the number of cooling degree days increases significantly, which also corresponds to warming of the climate.
• This change occurs for most countries, whether they have a dense population or not. Hence this warming is not due to random weather fluctuations and unlikely to be caused by urban heat island effects alone.

Since the climate change has a planetary impact the International Panel on Climate Change was created to provide policymakers with regular scientific assessments on climate change and potential future risks. Figure 5 shows a number of climate scenarios that plot potential global warming in function of CO₂ emissions and other greenhouse emissions. Current consensus amongst climate scientists is that a significant reduction of greenhouse gasses is required to keep global warming below 2 degrees Celsius.

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4. CO₂ equivalent greenhouse gas emissions and application type of fossil fuels

While CO₂ is a significant man-made greenhouse gas, other man-made greenhouse gasses as methane also have an impact as shown in Figure 6. Not shown is water vapor, the dominant greenhouse gas in the atmosphere. Water vapor can condense, reducing its amount by rain or snow. Positive (more water vapor) and negative (more clouds) feedback loops can exist between man-made greenhouse gasses and water vapor. Man made greenhouse gasses are non-condensable and build up in the atmosphere. Still they also decrease over time, with most methane removed in a time-span of about 12 years, whereas the CO₂ lifetime cannot be expressed as a single value [7].

Figure 7 shows the relative CO₂ emission footprint for different uses. These often rely on easy storage and availability of energy. Depending on selected country or region, the relative emissions per sector can vary significantly.

Nowadays it is easy to find estimates of how many grams of CO₂ a car emits per kilometer, which looks like a small quantity. However we know from Table 1 that the daily average CO₂ emissions per person only total 13.2 kg world-wide and only part of that is available for personal transport. So let's do some back of the envelope calculations of how far we can drive with different types of cars if we assume average emissions per person.

From Figure 7 we see that about 20% of CO₂ emissions are caused by transport. Let us assume that half of that is used for big machines such as boats, planes, trucks, tractors and bulldozers for example. So what's left for cars is 10% of CO₂ emissions per day per average person, or on average 1.3 kg CO₂ by day per person (kg CO₂/d/p). From the scenarios in Figure 5 we see that a reduction of carbon emissions is desirable, so we also do a what if analysis by halving this budget to 0.65 kg CO₂/d/p.

Results are shown in Table 2 for three use cases:

• Cars with an internal combustion engine (ICE). Assuming 250 gram CO₂ per kilometer (g/km) for a big car and 125 g/km for a small car.
• Electric cars, again in small and large form factor. For electric cars the fuel mix to generate electricity has an impact, and can vary from country to country, and also over time during a day, as visualized in [8]. For this analysis we assume electricity with a carbon intensity of 500, 250 and 125 gram of CO₂ emission per produced kiloWatt-hour (kWh). We see that electrical cars require less carbon emissions per kilometer than for internal combustion engines. And in general the trend is to decarbonize electricity production, resulting in less carbon emissions for electrical cars. Carbon emissions to produce and recycle cars are not considered to keep the analysis simple.
• For comparison we show an E-bike, assuming 1 kWh/100 km. This is substantially more efficient than a car. The weight of a car and its drag at higher speeds require more energy compared to a bike. In eco modus an E-bike is even more efficient.

The computations are easy to make, and for each scenario we see the range per day and per year per person. We see that big ICE cars consume most, resulting that their carbon budget is consumed the fastest, resulting in the lowest range. Choosing smaller form factors reduces carbon emissions. Electric cars further reduce emissions, especially when a cleaner energy mix is used producing electricity. This results in a larger available range per person for a fixed carbon budget. E-bikes fare best with a virtual unlimited range, which will be limited in practice by time to recharge its battery and its modest speeds.

5. Conclusion

The shown figures from Our World in Data show the evolution man-made carbon emissions over the past century, significantly increasing from 1950 onward. This has a significant impact on the atmosphere of our planet, and is likely correlated with rising global temperatures. Still reducing our fossil fuel addiction will likely mean changing our habits as well, as illustrated for personal transport. We see that electrical car result in less carbon for driving compared to cars with an internal combustion engine, and this improves when using a less carbon intensive energy mix for generating electricity. Still other means of transport, such as an e-bike outperfom cars by more than an order of magnitude. Also video calling can reduce overall transport. Hence we can expect a combination of techniquies will be used to reduce the carbon footprint of transportation.

Acknowledgement: many thanks to the Our World in Data team for open access to their data and interactive figures. Website: ourworldindata.org. Most Our World in Data work is licensed under CC BY 4.0, unless mentioned otherwise.

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