Total global GHG emissions (without LULUCF) taking into account implementation of the latest NDCs are estimated to be around 53.0 (51.4–54.5) Gt CO2 eq in 2025 and 51.5 (48.3–54.7) Gt CO2 eq in 2030, which are:
- In 2025, 54.0 per cent higher than in 1990 (34.4 Gt CO2 eq), 11.3 per cent higher than in 2010 (47.6 Gt CO2 eq) and approximately the same as in 2019 (52.9 Gt CO2 eq);
- In 2030, 49.8 per cent higher than in 1990, 8.3 per cent higher than in 2010 and 2.6 per cent lower than in 2019, as well as 2.8 per cent lower than the estimated level for 2025, indicating the possibility of global emissions peaking before 2030.
Projected range and progression of emission levels according to nationally determined contributions
Credit: UN Climate Change
In comparison, the total GHG emission levels resulting from implementation of NDCs (those submitted by 25 September 2023) presented in the previous version of this report were estimated to be around 53.2 (51.6–54.8) Gt CO2 eq in 2025 and 51.6 (48.3–54.8) Gt CO2 eq in 2030. Those levels are very similar (at 0.2 Gt CO2 eq higher for 2025 and 0.1 Gt CO2 eq higher for 2030) to the levels presented in this report, the estimates of which reflect a slight increase in aggregate NDC ambition level and updated emission data.
The projected total global GHG emission level taking into account full implementation of all latest NDCs continues to imply a possibility of global emissions peaking before 2030, with the lower bound of the 2030 emission level (48.3 Gt CO2 eq) estimated to be up to 8.6 per cent below the 2019 emission level (52.9 Gt CO2 eq) and 6.0 per cent below the lower bound of the estimated 2025 emission level (51.4 Gt CO2 eq). However, in order to achieve that peaking, the conditional elements of the NDCs need to be implemented, which depends mostly on access to enhanced financial resources, technology transfer and technical cooperation, and capacity-building support; availability of market-based mechanisms; and absorptive capacity of forests and other ecosystems.
Comparison of scenarios assessed in the Intergovernmental Panel on Climate Change Sixth Assessment Report with projected total and per capita global emissions according to nationally determined contributions
Credit: UN Climate Change
The estimated total GHG emission level for 2030 associated with implementation of Parties’ INDCs implied a stronger emission increase above historical levels: 68.1 (56.8–79.5) per cent above the 1990 level, 21.5 (13.3–29.8) per cent above the 2010 level and 9.1 (1.8–16.5) per cent above the 2019 level.
Historical and projected total global emissions according to nationally determined contributions
Credit: UN Climate Change
The contribution of Working Group III to the AR6 concludes that, in scenarios of limiting warming to 1.5 °C (with over 50 per cent likelihood by 2100) with no or limited overshoot over the course of the century, GHG emissions are reduced by 43 (34–60) per cent by 2030 relative to the 2019 level. In scenarios of keeping warming likely below 2 °C (with over 67 per cent likelihood) with mitigation action starting in 2020, emissions in 2030 are 27 (13–45) per cent below the 2019 level.
The Synthesis Report of the AR6 indicates that, to be in line with global modelled pathways to limiting warming to 1.5 °C (with over 50 per cent likelihood) with no or limited overshoot and those to limiting warming to 2 °C (with over 67 per cent likelihood), GHG emissions have to be reduced by 60 (49–77) per cent by 2035 relative to the 2019 level and by 35 (22–55) per cent by 2035 relative to the 2019 level respectively.
The absolute difference in the level of emissions by 2030 according to the latest NDCs and these IPCC scenarios is sizeable, despite progress compared with the level according to the INDCs as at 4 April 2016. The difference between the projected emission levels that do not take into account implementation of any conditional elements of NDCs and the emission levels in the scenarios of keeping warming likely below 2 °C (with over 67 per cent likelihood) by 2030 is estimated to be 14.9 (10.9–18.3) Gt CO2 eq. In relation to the scenarios of limiting warming to 1.5 °C (with over 50 per cent likelihood) and achieving net zero emissions this century, the gap is even wider, at an estimated 22.7 (21.2–27.7) Gt CO2 eq. However, assuming full implementation of all latest NDCs, including all conditional elements, the gap is slightly narrowed, towards 11.3 (7.3–14.7) Gt CO2 eq in relation to the aforementioned 2 °C scenarios and towards 19.2 (17.6–24.1) Gt CO2 eq in relation to the aforementioned 1.5 °C scenarios.
Historical and projected total global emissions according to nationally determined contribution
Credit: UN Climate Change
Taking into account the implementation of NDCs up until 2030, projected global mean temperatures are subject to significant uncertainty owing to the range of emission levels estimated for 2030 resulting from implementation of NDCs (including whether conditional elements are implemented or not), the range of illustrative emission extensions beyond 2030 and inherent climate system uncertainties. The best estimate of peak temperature in the twenty-first century (projected mostly for 2100 when temperature continues to rise) is in the range of 2.1–2.8 °C depending on the underlying assumptions.
In the context of the carbon budget consistent with 50 per cent likelihood of limiting warming to 1.5 °C (500 Gt CO2), cumulative CO2 emissions in 2020–2030 based on the latest NDCs would likely use up 86 per cent of the remaining carbon budget, leaving a post-2030 carbon budget of around 70 Gt CO2, which is equivalent to approximately two years of projected total global CO2 emissions by 2030. Similarly, in the context of the carbon budget consistent with a likely chance of keeping warming below 2 °C (estimated by the IPCC to be 1,150 Gt CO2 from 2020 onward), cumulative CO2 emissions in 2020–2030 based on the latest NDCs would likely use up around 37 per cent of the remaining carbon budget. For comparison, total global CO2 emissions between 1850 and 2020 are estimated by the IPCC to have amounted to 2,390 (2,150–2,630) Gt CO2.
A total of 50 per cent of Parties provided information on long-term mitigation visions, strategies and targets for up until and beyond 2050. Their total GHG emission level is estimated to be 39.2 (37.2–41.1) Gt CO2 eq in 2030, which is 4 per cent higher than in 2010 (with a range from 1 per cent lower to 9 per cent higher) and 6 (1–10) per cent lower than in 2019.
Mindful of the inherent uncertainty of such long-term estimates, and the need for full implementation of NDCs and LT-LEDS, the information indicates that these Parties’ total GHG emission level could be 63 (59–67) per cent lower in 2050 than in 2019 and their annual per capita emissions would be 2.4 (2.1–2.6) t CO2 eq by 2050. Under scenarios of limiting warming to likely below 2 °C (with over 67 per cent likelihood), annual per capita emissions are 2.4 (1.6–3.1) t CO2 eq; hence the estimated long-term per capita emissions of these Parties are at a level consistent with 2 °C scenarios. However, for scenarios of limiting warming to 1.5 °C (with 50 per cent likelihood by 2100) and achieving net zero CO2 emissions around 2050 and net zero GHG emissions this century, annual per capita emissions by 2050 are required to be two to three times lower, at 1.3 (0.6–2.1) t CO2 eq.