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Global carbon dioxide emissions

According to the latest global carbon budget, the total global fossil carbon dioxide (CO2) emissions in 2021 are returning towards their 2019 levels after an unprecedented drop in 2020.

This chart shows how global fossil carbon dioxide emissions have increased since the 1990s. Note the drops in the early 1990s, in 2008, and the huge drop in 2020. ©  Global Carbon Project

It’s expected to be a 5.3% increase to 36 billion tonnes of CO2 emission in 2021, relative to 2020.

In 2021, most of the world’s fossil fuel carbon emissions came from coal (40%), oil (32%), natural gas (21%), cement (5%) and flaring and other smaller sources (2%).

Just four regions accounted for about two-thirds of global fossil-fuel carbon emissions in 2020: China (31%), the USA (14%), the EU27 (7%), and India (7%).

The increase in CO2 emissions in China (7% higher than 2019) is taking coal emissions close to the peak in 2013. CO2 emissions in 2021 will grow by 5.3% relative to 2020.

The rebound is mainly due to a rise in coal use in the power and industry sectors in China. Most countries, including the European Union and the United States, showed an increase in emissions but remain below 2019 levels. 

The full effect due to the COVID-19 pandemic is still uncertain, but a further rise in emissions in 2022 cannot be ruled out if the surface transport and aviation sectors return to their pre-pandemic levels and coal use remains high.  

Overall, global carbon dioxide emissions have increased by 61 per cent since 1990, though the rate of increase has varied. The primary driver of this increase has been the continued growth in the use of fossil fuel energies such as coal, oil and natural gas. Changes in the pace of that growths have often been associated with the rise or fall of major economies, such as China and the Soviet Union.

Changes in global fossil CO2 emissions

Encouragingly, the last decade has seen a slowdown in the rate of increase in emissions. Between 2010 and 2019 the rate of increase was just below 1 per cent per year, compared to an average increase of 3 per cent per year during the early 2000s. Emissions in 2019 didn’t grow much, if at all, when compared to 2018.

This chart shows global fossil CO2 emissions growth for 2019-2021

Burning fossil fuels (such as coal, oil and gas) is by far the major source of human-derived carbon dioxide emissions. This source alone, with small contributions from cement manufacturing, accounts for around 90 per cent of total emissions. Land-use change (such as deforestation) is responsible for the remaining emissions.

The land and ocean CO2 sinks combined continued to take up around half of the CO2 emitted to the atmosphere averaged over the year

Emissions from the power and industry sectors are estimated to be above 2019 levels, while emissions in surface transport and aviation appear still below the 2019 level.

The extra carbon dioxide in our atmosphere has led to our oceans and land absorbing increasing amounts of carbon dioxide in response.

The remaining emissions stay in the atmosphere. This caused atmospheric carbon dioxide levels to increase by about 2.5 parts per million (ppm) in 2021 to reach 410 ppm.

The extra carbon dioxide in the atmosphere is causing our climate to warm. The world’s climate will only stabilise when the level of atmospheric carbon dioxide does as well. In other words, global carbon dioxide emissions need to be net zero for our climate to stop warming. Net zero emissions means that the amount of emissions, if any still left, need to be equivalent to an amount of carbon dioxide being removed from the atmosphere (either by new vegetation or by the direct removal with machines yet to be fully proved).

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