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COMMIT: Summary for Policymakers

Introduction The COMMIT project1 (Climate pOlicy assessment and Mitigation Modeling to Integrate national and global Transition pathways) was funded by the European Union. The COMMIT project’s main aim has been to improve the modelling of national low-carbon emission pathways and analysis of country contributions to the Paris Agreement’s global ambition. For this, the project had several key elements:

• capacity building of less experienced modelling teams, • mutual learning between national and global modelling teams, and • mutual learning between science and policy by informing long-term low-emission development

strategies. The main motivation for this aim was that a common understanding and coherent message from the research community in different parts of the world is crucial to support the international negotiation process on climate policy.

COMMIT consisted of a consortium of a large number of national teams, who regularly support domestic climate policy-making in their respective countries (Australia, Brazil, Canada, China, EU, India, Indonesia, Japan, Russia, South Korea, USA) and leading global integrated assessment modelling teams (PBL, PIK, IIASA, RFF-CMCC EIEE).

Here, we summarise the findings from the COMMIT policy brief and country fact sheets that were submitted as input to the Talanoa Dialogue and the newly developed bridge scenarios on both the global and the national levels. Other resources are the policy brief ‘Supporting the global stocktake’, the global stocktake indicators tool, and the poster and presentation on the bridge scenarios presented in the Research Dialogue.

1 The project was funded by the European Union’s DG CLIMA and EuropeAid under grant agreement No. 21020701/2017/770447/SER/CLIMA.C.1 EuropeAid/138417/DH/SER/MulitOC (COMMIT).

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Global: where are we, where do we want to go, and how do we get there? Where are we? Current climate policies are inconsistent with the objectives of the Paris Agreement (Figure SPM.1). NDCs are projected to lead to global greenhouse gas emissions in the range of 52–58 GtCO2e by 2030. The differences between current policy trends and the emission levels consistent with the Paris Agreement to stay well below 2 °C and 1.5 °C, by 2030 will amount to a global ‘emission gap’ from NDCs of approximately 15 and 22 GtCO2e, respectively. Failing to ratchet up ambitions for 2030 would require an even faster pace of decarbonisation after 2030 or the deployment of more carbon dioxide removal (CDR) technologies, in the long term, in order to still meet the Paris temperature targets by the end of the century, after a significant temperature overshoot.

Figure SPM.1: Global greenhouse gas emission pathways that limit global warming to well below 2 °C (global carbon budget 1000 GtCO2 over 2010–2100) and 1.5 °C (global carbon budget 400 GtCO2), starting cost-optimal mitigation in 2020, versus full implementation of conditional NDCs and current national policy trajectories. Source: Roelfsema et al. (2020)

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Where do we want to go? Scenarios limiting global warming to well below 2 °C or 1.5 °C project global emissions peaking by 2020 and declining rapidly afterwards, reaching net-zero CO2 emissions between 2070 and 2090 (2 °C) or between 2040 and 2060 (1.5 °C). It is important to have a near-zero emission ambition as an orientation for long-term planning, for countries, regions and even for cities, as well as for individual sectors (Figure SPM.2). A cost-optimal carbon-neutral global energy system may still imply that specific sectors or countries have residual CO2 emissions compensated by net negative CO2 emissions elsewhere. Net negative CO2 emissions, however, are associated with several risks. Climate policies need to be combined with broader sustainable development policies.

Figure SPM.2: CO2 emissions (%) by 2030 and 2050, relative to 2010, per sector. Red bars: model median, error bars: 10th–90th percentile range (note that the axis is cut off at -200%, while the error bar for AFOLU in 2050 reaches -266% under the 2 °C scenario and -292% under 1.5 °C). Values to the left of the dashed vertical line at -100% imply net negative emissions, while values to the right indicate residual emissions. Emissions from ‘Industrial processes’ correspond to IPCC categories 2A, B, C, E, while emissions from ‘Industry’ relate to fuel combustion (IPCC category 1A2). Based on the CD-LINKS database (McCollum et al., 2018)

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How do we get there? Analysis shows that there are several opportunities for strengthening current climate policies. Suppose all countries were to implement sectoral climate policies similar to successful examples observed in certain countries (good practice policies). In that case, annual greenhouse gas emission levels could be reduced to approximately 50 GtCO2e by 2030, compared to 60 GtCO2e under the current policies scenario. The massive transformation of global energy, industry, and land-use systems required to achieve the 1.5 °C and well below 2 °C global warming goals depends critically on policies that incentivise changes in investment patterns, technology uptake and household/business and community behaviour. The 2 °C and 1.5 °C scenarios exhibit a shift from fossil fuel (especially coal) to low-carbon and energy efficiency investments (Figure SPM.3).

Figure SPM.3: Key characteristics of decarbonisation pathways, based on Luderer et al. (2018). ‘Coal phase-out’ refers to the phase-out of conventional coal (without CCS). ‘Residual emissions’ refers to long-lived greenhouse gas emissions

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National: low-emission pathways How do these transitions play out on the national level? COMMIT used country-level models covering eleven major economies that incorporate a detailed and disaggregated representation of the energy demand and supply systems. These can capture national policy priorities and structural heterogeneities and simulate the future energy system evolution under different policy assumptions. National models were used to explore low-carbon pathways up to 2050, providing valuable insights on their implications for country-level emissions, energy system restructuring, energy–economy indicators, required investments and system costs.

National-level models show that different technological options can be used in each country, based on policy priorities, domestic energy resources and broad socio-economic considerations. The eleven countries analysed exhibit different structures of current GHG emissions by sector and gas; for example, non-CO2 and land-use emissions represent a large share of total GHG emissions in Brazil, Russia and Indonesia. Country specificities and policy priorities play a crucial role in designing nationally-relevant low-emission strategies and have to be consistently integrated into the quantitative assessment of low-carbon transition pathways (e.g. air pollution in China, energy security in the EU, nuclear power in Japan, energy exports in Russia). The different starting points and divergent dynamics of economic growth and energy system evolution lead to differentiated low-carbon transition pathways by country; however, generally, developed economies aim for a considerable reduction in their GHG emissions by 2050 (commonly by about 80%-90% from current levels), while pathways of developing countries depend on their domestic planning and policy priorities. For example, Chinese emissions would peak by 2030 and then decline rapidly, while a continuous increase (but at reduced rates relative to baseline trends) is projected for Indian emissions until 2050. This is consistent with the Paris Agreement that calls for all Parties to formulate long-term low emission development strategies, mindful of Article 2: taking into account common but differentiated responsibilities and respective capabilities, in the light of different national circumstances. For several developing countries, the global policy context is vital to ensure sufficient progress, as implementation depends on the provision of adequate finance, cooperation with industrialised countries, technology progress and knowledge sharing.

The analysis shows that all major economies' low-carbon scenarios made available via the COMMIT project are consistent with a pathway limiting global warming to below 2 °C. In particular, the national-level cumulative CO2 emissions over 2010-2050 are consistent with the range projected by several global models for cost-optimal scenarios assuming a global carbon budget of 1000 GtCO2 considered equivalent to likely below 2 °C increase in global mean temperature. For some countries, the low-carbon scenarios are also consistent with the global carbon budget of 400 GtCO2 considered equivalent to limiting the increase in global mean temperature to 1.5 °C. This is not the case for the India scenario, where the national-level model-based analysis shows larger cumulative emissions until 2050 compared to the global cost-optimal mitigation scenarios to 2 °C. This difference arises mainly due to the higher economic growth rate assumed in the national scenarios and the relatively larger allocation of mitigation efforts to the developing countries by global inter-temporal models applying a universal carbon tax across all countries and sectors.

The national scenarios illustrate that in the low-carbon context, the eleven major economies are projected to 1) improve the carbon intensity of their economy, 2) diversify their energy and power generation mix towards low-carbon sources, 3) improve their energy efficiency, and 4) use a diversity of mitigation options across countries towards the low-carbon transition. These national model-based scenarios are not meant to instruct the governments on what to do; their objective is to inform policymakers and other stakeholders on the challenges and opportunities of potential mid-century low-carbon strategies. The key decarbonisation pillars that are common to all countries examined (albeit at different rates) include (Figure SPM.4):

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1) Expansion of renewable energy sources in power generation (mainly solar PV and wind power) and in the transport and heating uses (biofuels, RES-based electricity, bioenergy). The share of renewable sources in primary energy demand would increase from the current global average of 18% to 20%-52% by 2050. The increase is more significant in developed economies (EU, USA, Canada), where the share of renewable sources in primary energy consumption is projected to amount to approximately 50% by 2050.

2) Accelerated energy efficiency improvements in all demand sectors (buildings, transport, industries). In the low-carbon national scenarios, the final energy intensity of GDP is projected to decline by 35%-73% across countries over 2015-2050.

3) Electrification of final energy demand, both in mobility and in heating end-uses. The share of electricity in final energy demand would increase from the current global average of 20% (14%-25% across the eleven major G-20 economies) to between 20% and 80% by 2050. The electrification strategy is more prominent in developed economies aiming for significant emission reductions from 2015 levels.

The national-level analyses illustrate that the deployment of other low-carbon options (i.e. CCS, nuclear power, advanced biofuels, hydrogen, synthetic fuels) highly depends on national specificities, policy considerations and priorities. The profound energy system decarbonisation of developed economies points to the need for full decarbonisation of end-uses driven by deep electrification, advanced biofuels and deployment of new clean energy forms (such as hydrogen and clean synthetic fuels). To accommodate high shares of variable renewables, various electricity storage options are deployed. The technology mix is also based on specific national priorities, e.g. nuclear power in Japan. In countries with high non-CO2 and land-use emissions (such as Brazil), the focus is on eliminating these GHG sources. Overall, the different low-carbon strategies require the development of policy designs tailored to meet the needs of specific countries, taking into account national priorities and broad socio-economic considerations (e.g. the role of energy exports in Russia or the need to improve energy supply security in the EU and Japan).

Figure SPM.4: Energy system transformation as projected by national-scale models between 2015 and 2050 (a) RES share in primary energy consumption (in %), b) Share of electricity in final energy consumption (in %), c) Reduction in energy intensity of GDP over 2015-2050

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By comparing the emission and energy system indicators presented in the national fact sheets (i.e. GHG emissions, RES share, peak emission years, energy and carbon intensity of GDP), the mitigation effort across countries can be evaluated to derive appropriate indicators to monitor mitigation effort and future pathways. However, the numbers presented in the fact sheets are sensitive to exogenous assumptions, the modelling framework used and how policies are represented in each model. The exogenous assumptions include GDP growth, global energy prices and technology development. The country analysis has benefited from the detailed representation of national policy choices, priorities and specificities and the in-depth analysis of possible evolution of the energy–economy system by national teams. The establishment of links between national and global modelling approaches enhances the policy relevance and realism of model-based assessments, essential for future climate negotiations in the post-Paris era.

The indicators presented in the study can help policymakers to identify the most critical areas and sectors for increasing climate policy ambition in the following decades. Modelling results show that the national low-carbon mid-century strategies provide a good starting point for global mitigation pathways to achieve the Paris Agreement long-term objectives. The process towards the Paris Agreement's signature has established a positive dynamic in the international climate policy landscape that is important for future policy and business strategies. Despite the significant policy, social and financial challenges towards energy system restructuring (i.e. redirection of investment towards clean energy technologies), establishing a clear, ambitious and well-anticipated policy and investment framework in major emitting economies can lead the way towards the low-carbon transition. Therefore, the Paris Agreement should establish a clear mechanism to facilitate strengthened climate targets by all Parties and to allow for the regular and timely revision of national contributions; the design of national low-emission development pathways for major carbon emitters is essential to close the “gap” with the aspirational 2 °C and 1.5 °C mitigation targets, mitigate the risks for carbon lock-in and integrate national policy priorities in the design of low-carbon transition pathways and mid-century strategies

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A bridge over the global and national emission gaps One key aspect of the Paris Agreement is limiting global average temperature increase to well below 2 °C by the end of the century. To achieve the Paris Agreement goals, countries need to submit, and periodically update, their Nationally Determined Contributions (NDCs). Recent studies show that NDCs and currently implemented national policies are insufficient to cover the ambition level of the temperature limit agreed upon in the Paris Agreement, meaning that we need to collectively increase climate action to stabilise global warming at levels considered safe. Closing the remaining emissions gap between current climate policies and Nationally Determined Contributions (NDCs) and the global emissions levels needed to achieve the Paris Agreement’s climate goals will likely require a comprehensive package of policy measures. National and sectoral policies can help fill the gap. However, success stories in one country cannot be automatically replicated in other countries but need to be adapted to the local context. COMMIT developed a new bridging scenario based on nationally relevant measures informed by interaction with country experts. The scenario was implemented with an ensemble of global integrated assessment models (IAMs). A global roll-out of these good practice policies closes the emissions gap between current NDCs and a cost-optimal well below 2 °C scenarios by two thirds by 2030 and more than fully by 2050 (Figure SPM.5). The Bridge scenario leads to a scale-up of renewable energy (reaching 50%-85% of global electricity supply by 2050), electrification of end-uses, efficiency improvements in energy demand sectors, and enhanced afforestation and reforestation. Early action via good-practice policies is less costly than a delay in global climate cooperation.

Figure SPM.5: Global GHG emissions (Gt CO2eq/year) between 2010 and 2050, as projected by the global models. Vertical bars: model range in 2050. Circles: model median in 2050. Thick solid lines: median.

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The Bridge scenario was also implemented in eleven national Integrated Assessment Models (IAMs) for Australia, Brazil, Canada, China, European Union (EU), India, Indonesia, Japan, Russia, South Korea and the United States, that provide the least-cost, low-carbon scenarios up to 2050 (Figure SPM.6).

Figure SPM.6: Greenhouse gas emissions trajectories from national models (lines) and global models (wedges) up to 2050. For China, Canada, India and Russia, only CO2 emissions are presented.