14 December 2015
The Climate Scoreboard shows the progress that national contributions (INDCs) to the UN climate negotiations will make assuming no further action after the end of the country’s pledge period (2025 or 2030). Our analysis shows that the national contributions to date, with no further progress post-pledge period, result in expected warming in 2100 of 3.5°C (with a range of uncertainty of 2.0 – 4.6°C).
The Climate Scoreboard uses the C-ROADS climate policy simulation model to analyze the impact of the “Intended Nationally-Determined Contributions (INDCs)—pledges to limit greenhouse gas emissions—to the UN climate negotiations. The Scoreboard analysis above shows the expected impact of the pledges nations have made to date, assuming (1) the pledges are fully implemented, and (2) assuming no further reductions beyond those that have been formally pledged, specifically, actions after the end of the country’s pledge period (2025 or 2030).
Any analysis, including ours, that offers an expected temperature change in 2100 includes assumptions about what will happen after the formal contributions end in 2025 or 2030. Thus, we also analyze scenarios in which nations are assumed to pledge and implement additional action beyond 2030. Greater ambition leads to further reductions in expected warning. For example:
- INDC Strict – No change after national contribution pledge period: 3.5°C (6.3°F);
- Ratchet 1 – Plus, pledged reductions continue after pledges end (2025 or 2030): 3.2°C (5.8°F);
- Ratchet 2 – Plus, China includes other GHGs and reduces emissions after they peak in 2030 at up to 2%/year: 3.0°C (5.4°F);
- Ratchet 3 – Plus, other developing countries without commitment also peak by 2035: 2.6°C (4.6°F);
- Ratchet Success – Plus, all countries peak before 2030 and then reduce steadily: 1.8°C (3.2°F).
- 1.5°C – Plus, developed countries make deeper cuts and all others peak no later than 2025 and then reduce steadily: 1.5°C (2.7°F).
- Yellow line – represents the “business-as-usual” scenario, which is what the estimated global temperature increase in 2100 will be if greenhouse gas emissions are not reduced. Based on IPCC’s RCP 8.5 scenario.
- Blue line – represents the estimated global temperature increase in 2100 if current INDCs are fulfilled and no further action is committed (this follows the ‘INDCs strict’ pathway). The shaded blue curve shows the uncertainty in the climate system’s response to emissions.
- Green line – represents the goal of limiting the temperature increase to 1.5°-2.0°C.
The image below shows potential emissions pathways and their long-term impacts in temperature.
With action to reduce fossil fuel emissions and greenhouse gas emissions from other sources, the world can still realize the pathway that keeps warming below 2.0°C this century.
How Could Paris Climate Talks Ratchet Up To Success?
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