15th November 2017
In addition to the global temperature outcomes of policies and pledges, the CAT also assesses the expected absolute emissions in 2020, 2025, and 2030 and compares these with benchmark emissions consistent with benchmark pathways in line with the temperature goal in the Paris Agreement.
We base our assessment on the emissions scenarios currently available in the scientific literature, mindful of the assumptions and limitations underlying these studies. The scenarios limit warming below 1.5°C by 2100 with ≥50% probability, and below 2°C in the 21st century with about an 80% probability. We use these scenarios as indicative of the Paris Agreement’s long-term temperature goal, but note these scenarios should not be seen as a definitive interpretation of the Paris Agreement.
A new and more diverse set of scenarios that limit warming to 1.5°C or below are now being developed by the scientific community and will become available in the open literature. The CAT will update its Paris Agreement benchmark scenarios in 2018 to reflect the most recent available scientific literature (more details at CAT Rating System Update). The CAT also presents results in relation to a pathway consistent with limiting warming to 2°C with likely (≥66%) probability, for comparative purposes.
As of November 2017, a substantial gap remains between the levels of emissions in 2025 and 2030 projected in the NDCs submitted to the UNFCCC and the lower levels that would be consistent with the temperature goal in the Paris Agreement.
The benchmark emissions from a 1.5°C compatible pathway are 38 GtCO2e in 2025 and 32 GtCO2e in 2030. Comparing these with the emissions from the pledges submitted by November 2017, which results in total global emissions of 52–55 GtCO2e in 2025 and 54–58 GtCO2e in 2030 the CAT calculates a gap 14–17 GtCO2e in 2025 and 22–26 GtCO2e in 2030.
The benchmark emissions from a 2°C compatible pathway are higher (41 GtCO2e in 2025 and 38 GtCO2e for 2030), and comparing these to the global emissions from the pledges quoted above, the gap ranges between 11–14 GtCO2e for 2025 and 16–20 GtCO2e in 2030.
With the NDCs submitted to date, the CAT projects that total global emissions would be 52-55 GtCO2e in 2025 and 54-58 GtCO2e in 2030, significantly above present emissions of about 50 GtCO2e. We therefore estimate the emissions gap at 14-17 GtCO2e in 2025, growing to about 22-26 GtCO2e in 2030.
Currently implemented policies are not strong enough to achieve the pledges governments have made under the Paris Agreement framework and are estimated to result in emissions that are 1–2 GtCO2e higher than the pledge pathway emissions in the benchmark years. Therefore, the gaps between current policy projections and the 1.5°C and 2°C benchmarks are higher, namely 16–17 GtCO2e in 2025 and 24–27 GtCO2e in 2030 for a 1.5°C compatible pathway and 13–14 GtCO2e in 2025 and 18–22 GtCO2e in 2030 for a 2°C compatible pathway.