Behind the UN Climate Pledge Analysis
The Climate Scoreboard analysis assesses how far the plans submitted to the UN will go to address climate change. These plans include the Nationally Determined Contributions (NDCs), Intended Nationally Determined Contributions (INDCs), and Long-Term Strategies submitted by nations to the UN Framework Convention on Climate Change. This analysis is done with C-ROADS, a scientifically reviewed climate simulator that is designed to aggregate the proposals of countries and country groups to calculate long-term global climate impacts such as carbon dioxide concentration and temperature. C-ROADS was built by Climate Interactive, Ventana Systems, and the MIT Sloan School of Management and is available to download for free. C-ROADS is calibrated to the Intergovernmental Panel on Climate Change’s (IPCC) Fifth Assessment Report results.
National Climate Plans and Additional Scenarios
- National Plans – 3.3°C (6.0°F) – No change after national contribution pledge period.
- <2.0°C Path – 1.8°C (3.3°F) – All countries peak by 2030 and then reduce steadily, with rates in the post-2030 period faster in the developed countries (5%/yr) than in the developing countries (3.5%/yr).
- 1.5°C Path – 1.5°C (2.8°F) – All developed countries peak by 2025 and then reduce steadily at 10%/yr; all developing countries peak no later than 2030 and then reduce steadily at 8%/yr.
Assumptions Behind the Scenarios:
In order to assess the cumulative impact of all the pledges and offer a projected temperature in 2100, we had to make some assumptions that are highlighted below. Many points are also explained in our FAQs.
- We only include Nationally Determined Contributions (NDCs), Intended Nationally Determined Contributions (INDCs), and Long-Term Strategies submitted to the UNFCCC that are unconditional.
- For the “National Plan” scenario, which is the one displayed on the Scoreboard, we assume no continued reductions by developed countries and no further action from developing countries beyond the timeframe of their plans. Specifically, there are four primary types of pledges, and we make the following assumptions for them:
- Absolute reductions – For countries that are making absolute emissions reductions, we assume that emissions stay constant after 2025-2030 (the end of the pledge period), unless an NDC states otherwise. For example, Australia has offered to reduce their greenhouse gas emissions 26% below 2005 levels by 2030. After that, given there is no formal post-2030 pledge, we assume that Australia’s emissions do not increase nor continue to decrease, but stay constant at that new level.
- Relative to a reference scenario – For countries that are reducing emissions from a reference scenario or business as usual (BAU) level, we assume they stay at the target level below the reference scenario after the pledge period. For example, Kenya has pledged to reduce their emissions 30% below their BAU by 2030. After 2030, we assumed that the emissions would continue to stay 30% below their Reference Scenario. Since the Reference Scenario is increasing, however, emissions increase at the same rate as the Reference Scenario.
- Peaking – Emissions grow until year target peak year. For example, China has said they will peak their CO2 emissions by 2030. We assumed that the rate of growth in emissions would slow starting in 2015, approaching a flat trajectory gradually. After the peaking date, emissions would stay level. (Note: other greenhouse gas emissions continue to increase given they were not covered by China’s pledge).
- Emissions intensity reduction – Change in emissions relative to the GDP of the country. For example, India reducing emissions intensity 40% (we took the low end of the pledge, which was 35-40%) by 2030. Up to 2030, we calculate emissions by using the GDP growth. After 2030, emissions intensity stays 40% below the growing GDP.
- In the <2°C and 1.5°C scenarios, we assume continued action and reductions after the period when the current NDCs end.
- The regional distribution of emissions reductions in the <2°C and 1.5°C scenarios is one representation of many possible approaches. We assume that developed countries move faster than developing countries.
- We assume that proposals will be fully implemented, in accordance with the dates specified in the plans.
- Some countries have made proposals for specific actions (rather than for emissions targets). If we don’t have a good estimate for the impact of those actions on emissions then we don’t include the action in our analysis.
- We assume emission reductions cover all greenhouse gas emissions unless specified otherwise. In some cases for smaller countries, the structure of the model requires us to assume that they take proportional action on other greenhouse gases.
Assumptions inherent in C-ROADS:
- The C-ROADS “reference scenario” (also called “business as usual”) is based on the RCP 8.5 scenario from the Intergovernmental Panel on Climate Change’s (IPCC) Fifth Assessment Report (AR5) report, but has been updated to reflect trends of GDP per capita and CO2 per GDP over the last decade.
- C-ROADS uses a climate sensitivity of 3 (that is 3°C of temperature increase for a doubling of CO2 concentration.)
- There are positive feedback loops in the real climate system that are not modeled in the current version of C-ROADS. Additionally, C-ROADS is based upon and calibrated to the results of models from the IPCC’s AR5.
- C-ROADS allows inputs of emissions reductions targets for 12 countries (U.S., Japan, Russia, Canada, Australia, South Korea, China, India, Brazil, Mexico, South Africa, Indonesia) and three blocs of countries (EU, “other developed” and “other developing”). For the 12 countries with individual controls, we adjust that country’s modeled emissions from a reference scenario (based on the IPCCs RCP 8.5 scenario).
- NDCs accounted for in “other developed” or “other developing” were calculated in accordance with that country’s percentage of emissions from the entire group. In other words, each nation’s proposals are scaled to their actual share of emissions within their bloc.
- For more information on C-ROADS, please consult the peer-reviewed journal article or C-ROADS Reference Guide.
Credits and Contact Information
The Climate Scoreboard and associated images are copyright 2017 by Climate Interactive, but you are welcome to use the unaltered Scoreboard image, data, and Flash animation in any form.
Inquiries, contact info [at] climateinteractive.org.
Resources on the tools behind the Climate Scoreboard analysis:
- Access C-ROADS
- Watch a video about the scenarios
- C-ROADS Frequently Asked Questions (FAQs)
- Comments from C-ROADS users
- C-ROADS Scientific Review one-page summary
- C-ROADS Technical Reference Guide on the simulator, including simulation purpose, structure, parameters, test results, and bibliography
- A peer-reviewed journal article on C-ROADS. Sterman, John, Thomas Fiddaman, Travis Franck, Andrew Jones, Stephanie McCauley, Philip Rice, Elizabeth Sawin, Lori Siegel. (2013) Management Flight Simulators to Support Climate Negotiations. Environmental Modelling and Software.
- A second Journal article on C-ROADS published in System Dynamics Review July 2012. (translated into Chinese)
- Press coverage of C-ROADS and other Climate Interactive tools.
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