Global carbon emissions in 2023

Global carbon emissions in 2023 | Nature Reviews Earth & Environment

Global CO2 emissions for 2023 increased by only 0.1% relative to 2022 (following increases of 5.4% and 1.9% in 2021 and 2022, respectively), reaching 35.8 Gt CO2. These 2023 emissions consumed 10–66.7% of the remaining carbon budget to limit warming to 1.5°C, suggesting permissible emissions could be depleted within 0.5–6 years (67% likelihood).

Key points

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Data from the Carbon Monitor indicate 35.8 Gt CO2 were emitted globally in 2023.
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Although the trend is upwards, the pace of growth has been slowing, suggesting global emissions might have plateaued.
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India overtook the EU as the third highest emitter globally.

Annual global CO2 emissions dropped markedly in 2020 owing to the COVID-19 pandemic, decreasing by 5.8% relative to 2019 (ref. 1). There were hopes that green economic stimulus packages during the COVD crisis might mark the beginning of a longer-term decrease in global emissions toward net-zero emissions, but instead emissions rebounded and quickly exceeded pre-pandemic levels by 2021. However, year-on-year growth has slowed, with 5.4% increases in 2021 (ref. 2) (reaching 35.1 Gt CO2) and 1.9% increases in 2022 (ref. 3) (reaching 35.7 Gt CO2), rapidly using up the remaining carbon budget. Here, we outline global CO2 emissions (encompassing fossil fuel combustion and cement production) from the Carbon Monitor project ( https://carbonmonitor.org) for the year 2023.

Global CO2 emissions in 2023

Overall, global CO2 emissions in 2023 reached 35.8 ± 0.3 Gt CO2, an all-time high (Fig. 1). Total emissions were 35.3, 33.3, 35.1 and 35.7 in 2019–2022, meaning year-on-year changes of –5.8% from 2019 to 2020, 5.4% from 2020 to 2021, 1.9% from 2021 to 2022 and 0.1% from 2022 to 2023. This slight increase of 0.1% (–0.6 to + 1.1%) from 2022 to 2023 is less than the 1.1 ± 1.0% increase forecast by the Global Carbon Project (GCP) 4. Although difficult to predict, the continued deceleration in growth rates might signal a plateauing or peaking of global CO2 emissions in 2023, as has been suggested by the International Energy Agency (IEA) 5. The trajectory of emissions in 2024 will offer further evidence.

Historical CO2 emissions from fossil fuel combustion and the process of cement production (‘Fossil CO2’) 8 coloured by industry sector, and those with land-use change (LUC) emissions 4(‘Fossil + LUC’). International bunkers describe emissions from international aviation and international shipping. The inset displays daily near-real-time CO2 emissions since 2019 from the Carbon Monitor 1 initiative and year-on-year percent changes. Note that total emissions and percent changes have been revised slightly from earlier estimates 2, 3 owing to revised data and updated methodologies 9, 10. Global CO2 emissions continued to grow after a brief decline in 2020, but the rate of that growth slowed in 2023; if these progressions continue, the remaining 1.5 °C carbon budget could be used within 0.5–6 years.

The sectoral contributions to these emissions are broadly similar to previous years. The power sector accounted for 38.4% of global CO2 emissions, industry for 29.0%, ground transportation for 18.6%, residential for 9.4%, international bunkers (international aviation and shipping) for 3.5%, and domestic aviation for 1.0%. Moreover, the pattern of decelerating growth of 2023 global emissions is also evident at the sectoral level. For instance, year-on-year changes in power sector emissions went from + 0.9% in 2022 to –0.2% in 2023, industry emissions from + 1.6% to –0.8%, residential emissions from + 0.9% to –5.5%, and international bunkers from + 18.1% to + 8.9%. However, there were exceptions: ground transportation growth increased from + 2.5% in 2022 to + 3.1% in 2023, while domestic aviation rebounded from –1.0% in 2022 to + 14.0% in 2023. Nevertheless, both domestic and international aviation remain below pre-pandemic levels (2023 emissions were –1.9% and –9.6% less than 2019, respectively).

At the country level, combined emissions from the top five emitters remain similar to previous years. In descending order, China, the United States, India, the European Union (excluding the UK), and Russia collectively accounted for 64% of global emissions, or 23.0 Gt CO2. However, interannual fluctuations are apparent when comparing 2022 and 2023, making it difficult to predict long time trends toward zero emissions. For instance, emissions from China (the largest emitter) decreased by 1.9% to 11.0 Gt CO2 in 2022 but rebounded + 2.9% to 11.3 Gt CO2 in 2023. By contrast, other regions have maintained earlier increases. Emissions from India, for example, surged by 6.9% to 2.6 Gt CO2 in 2022 and by another 4.4% to 2.8 Gt CO2 in 2023; in doing so, India surpassed the EU to become the third highest emitter. Russia exhibited a similar increase, whereby emissions increased by 1.0% to 1.5 Gt CO2 in 2022 and grew by 2.4% to 1.6 Gt CO2 in 2023. Meanwhile, emissions began to decrease in other regions. In the United States, emissions increased by 3.0% to 5.0 Gt CO2 in 2022 but decreased by 2.4% to 4.9 Gt CO2 in 2023. Similarly, the European Union’s emissions increased by 0.3% to 2.8 Gt CO2 in 2022 but decreased by 6.2% to 2.6 Gt CO2 in 2023.

Carbon budget countdown

Global CO2 emissions are rapidly depleting reported carbon budgets — that is, the amount of carbon that can be released while limiting anthropogenic warming to 1.5 °C and 2 °C above pre-industrial temperatures, as outlined by the Paris Agreement. At 67% likelihood, the IPCC set this budget (starting from 2020 and assuming no overshoot) at 400 Gt CO2 for 1.5 °C warming 6. The years 2020, 2021 and 2022 depleted the budget by 9.4% (38 Gt CO2), 9.9% (39 Gt CO2) and 10.0% (40 Gt CO2), respectively, with 2023 emissions using a further 10% (40 Gt CO2). A total of 243 Gt CO2 remain, which could be exhausted within 6.1 years unless emissions fall sharply. At 83% likelihood, the post-2020 budget to avoid 1.5 °C is only 300 Gt CO2. In this case, 2023 emissions depleted 13.3% of the budget, with the remaining 143 Gt CO2 potentially exhausted within 3.6 years. The carbon budgets for 2 °C warming are larger. At 67% likelihood, the 2°C budget is 1,150 Gt CO2, 3.5% of which was used in 2023; the remaining 993 Gt CO2 could be exhausted within 24.8 years unless growth rates fall. At 83% likelihood, the 2 °C budget is 900 Gt CO2, 4.4% of which was used in 2023; 743 Gt CO2 remains that could be used within 18.6 years.

Other estimates of the remaining carbon budget imply much lower permissible emissions 7. Under those tighter constraints, only 250 Gt CO2 or 60 Gt CO2 remain from January 2023 to achieve the 1.5 °C target at 50% and 66% likelihood, respectively. Accordingly, they convey a more dire timeline. Focusing on the 66% scenario to facilitate comparison with the IPCC likelihoods above, 2023 emissions used 66.7% of the budget, leaving only 20 GtCO2; at the current pace, the entire 1.5 °C target could be depleted halfway through 2024. By comparison, 1,200 Gt CO2 or 940 Gt CO2 remains to constrain warming to 2 °C at 50% and 66% likelihood, respectively. For the 66% scenario, 2023 emissions used 4.2% of the budget, leaving 900 Gt CO2, which could be diminished within 22.6 years.

Summary

Detailed and near-real-time monitoring of CO2 emissions since 2019 has enabled timely insights into changes in CO2 emissions worldwide. In 2023, global annual emissions reached an all-time high of 35.8 Gt CO2, which reflects a very slight increase of 0.1% year-on-year. While these estimates indicate that post-pandemic emissions growth is slowing, there is not yet convincing evidence of a peak in global emissions — CO2 emissions continue to rise, particularly in China, India and Russia. Given dwindling carbon budgets to constrain warming to 1.5 °C — the threshold above which climate impacts will become even more disastrous — the absence of a clear downward trend in emissions is troubling. The window of opportunity to meet the most ambitious international climate goals is rapidly closing. Meeting such goals would entail nations accelerating their decarbonization efforts and embracing the consensus from COP28 to “transition away from all fossil fuels in energy systems” as quickly as possible. This call to action is particularly pressing for countries with energy systems heavily reliant on coal, like China, India and Russia, where power generation accounts for approximately half of national carbon emissions. Transitioning these countries’ power sectors away from coal is critical for international climate mitigation efforts. Continued monitoring of global and national carbon emissions could be instrumental in evaluating the efficacy of these efforts.
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Liu, Z., Deng, Z., Davis, S.J. et al. Global carbon emissions in 2023. Nat Rev Earth Environ (2024). https://doi.org/10.1038/s43017-024-00532-2
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DOI: https://doi.org/10.1038/s43017-024-00532-2