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==== 4.2.4.3 Mid-century Low Emission Strategies at the National Level in the Academic Literature ====

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Since the 2000s, an increasing number of studies have quantified the emission pathways to mid-century by using national scale models. In the early stages, the national emission pathways were mainly assessed in the developed countries such as Germany, UK, France, the Netherlands, Japan, Canada, and USA. For example, the Enquete Commission in Germany identified robust and sustainable 80% emission reduction pathways ( [[#Deutscher%20Bundestag--2002|Deutscher Bundestag 2002]] ). In Japan, 2050 Japan Low-Carbon Society scenario team (2008) assessed the 70% reduction scenarios in Japan, and summarised the necessary measures to ‘Dozen Actions towards Low-Carbon Societies’.

Among developing countries, China, India, South Africa assessed their national emission pathways. For example, detailed analysis was undertaken to analyse pathways to China’s goal for carbon neutrality ( [[#EFC--2020|EFC 2020]] ). In South Africa, a [[#Scenario%20Building%20Team--2007|Scenario Building Team (2007)]] quantified the Long Term Mitigation Scenarios for South Africa.

Prior to COP21, most of the literature on mid-century mitigation pathways at the national level was dedicated to pathways compatible with a 2°C limit (see Box 4.2 for a discussion on the relationship between national mitigation pathways and global, long-term targets). After COP21 and the IPCC SR1.5, literature increasingly explored just transition to net zero emissions around 2050. This literature reflects on low-emissions development strategies (cognate with SDPS, [[#4.3.1|Section 4.3.1]] ) and policies to get to net zero CO 2 or GHG emissions (Garg and Waisman 2021) (Cross-Chapter Box 5 in this chapter).

provides a snapshot of this literature. For a selected set of countries, it shows the mid-century emission pathways at national scale that have been registered in the International Institute for Applied Systems Analysis (IIASA) national mitigation scenario database built for the purpose of this Report (Annex III.3.3). Overall, the database contains scenarios for 50 countries. Total GHG emission are the most comprehensive information to assess the pathways on climate mitigation actions, but energy-related CO 2 emissions are the most widely populated data in the scenarios. As a result, Figure 4.2 shows energy-related CO 2 emission trajectories. Scenarios for EU countries show reduction trends even in the reference scenario, whereas developing countries and non-European developed countries such as Japan and USA show emissions increase in the reference. In most countries plotted on , studies have found that reaching net zero energy related CO 2 emissions by 2050 is feasible, although the number of such pathways is limited.

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[[File:a1bcaa26203668c0c2be238e8a637c4e IPCC_AR6_WGIII_Figure_4_2.png]]

'''Figure 4.2 | Energy related CO''' 2 '''emission pathways to mid-century from existing studies.''' Source of the historical data: Greenhouse Gas Inventory Data of UNFCCC ( https://di.unfccc.int/detailed_data_by_party )

The literature underlines the differences induced by the shift from ‘2°C scenarios’ (typically assumed to imply mitigation in 2050 around 80% relative to 1990) to ‘1.5°C scenarios’ (typically assumed to imply net zero CO 2 or GHG emissions in 2050) (Box 4.2). For Japan, [[#Oshiro--2018|Oshiro et al. (2018)]] shows the difference between the implications of a 2°C scenario (80% reduction of CO 2 in 2050) and a 1.5°C scenario (net zero CO 2 emission in 2050), suggesting that for a net zero CO 2 emission scenario, BECCS is a key technology. Their sectoral analysis aims in 2050 at negative CO 2 emissions in the energy sector, and near-zero emissions in the buildings and transport sectors, requiring energy efficiency improvement and electrification. To do so, drastic mitigation is introduced immediately, and, as a result, the mitigation target of Japan’s current NDC is considered not sufficient to achieve a 1.5°C scenario. [[#Jiang--2018|Jiang et al. (2018)]] also show the possibility of net negative emissions in the power sector in China by 2050, indicating that biomass energy with carbon capture and storage (CCS) must be adopted on a large scale by 2040. [[#Samadi--2018|Samadi et al. (2018)]] indicate the widespread use of electricity-derived synthetic fuels in end-use sectors as well as behavioural change for the 1.5°C scenario in Germany.

In addition to those analyses, [[#Vishwanathan--2018b|Vishwanathan et al. (2018b)]] , [[#Chunark--2018|Chunark and Limmeechokchai (2018)]] and [[#Pradhan--2018b|Pradhan et al. (2018b)]] build national scenarios in India, Thailand and Nepal, respectively, compatible with a global 1.5°C. Unlike the studies mentioned in the previous paragraph, they translate the 1.5°C goal by introducing in their model a carbon price trajectory estimated by global models as sufficient to achieve the 1.5°C target. Because of the high economic growth and increase of GHG emissions in the reference case, CO 2 emissions in 2050 do not reach zero. Finally, the literature also underlines that to achieve a 1.5°C target, mitigation measures relative to non-CO 2 emissions become important, especially in developing countries where the share of non-CO 2 emissions is relatively high. ( [[#La%20Rovere--2018|La Rovere et al. 2018]] ) treat mitigation actions in AFOLU sector.

[[IPCC:Wg3:Chapter:Chapter-3|Chapter 3]] reported on multi-model analyses, comparison of results using different models, of global emissions in the long term. At the national scale, multi-model analyses are still limited, though such analyses are growing as shown in Table 4.7. By comparing the results among different models and different scenarios in a country, the uncertainties on the emission pathways including the mitigation measures to achieve a given emission target can be assessed.

Another type of multi-model analysis is international, in other words, different countries join the same project and use their own national models to assess a pre-agreed joint mitigation scenario. By comparing the results of various national models, such projects help highlight specific features of each country. More robust mitigation measures can be proposed if different types of models participate. These activities can also contribute to capacity building in developing countries.

'''Table 4.7 | Examples of research projects on country-level mitigation pathways in the near to medium-term under the multi-nat''' '''ional analyses.'''

{| class="wikitable"
|-
! Project name

! Features

|-
| DDPP (Deep Decarbonisation Pathways Project)

| 16 countries participated and estimated the deep decarbonisation pathways from the viewpoint of each country’s perspective using their own models ( [[#Waisman--2019|Waisman et al. 2019]] ).

|-
| COMMIT (Climate Policy assessment and Mitigation Modelling to Integrate national and global Transition pathways)

| This research project assessed the country contributions to the target of the Paris Agreement ( [[#COMMIT--2019|COMMIT 2019]] ).

|-
| MAPS (Mitigation Action Plans and Scenarios)

| The mitigation potential and socio-economic implications in Brazil, Chile, Colombia and Peru were assessed ( [[#Delgado--2014|Delgado et al. 2014]] ; [[#Zevallos--2014|Zevallos et al. 2014]] ; Benavides et al. 2015; [[#La%20Rovere--2018|La Rovere et al. 2018]] ). The experiences of the MAPS programme suggests that co-production of knowledge by researchers and stakeholders strengthens the impact of research findings, and in depth studies of stakeholder engagement provide lessons ( [[#Boulle--2015|Boulle et al. 2015]] ; [[#Raubenheimer--2015|Raubenheimer et al. 2015]] ; [[#Kane--2018|Kane and Boulle 2018]] ), which can assist building capacity for long-term planning in other contexts ( [[#Calfucoy--2019|Calfucoy et al. 2019]] ).

|-
| CD-LINKS (Linking Climate and Development Policies – Leveraging International Networks and Knowledge Sharing)

| The complex interplay between climate action and development at both the global scale and some national perspectives were explored. The climate policies for G20 countries up to 2015 and some levels of the carbon budget are assessed for short-term and long-term, respectively ( [[#Rogelj--2017|Rogelj et al. 2017]] ).

|-
| APEC Energy Demand and Supply Outlook

| Total 21 APEC countries assessed a 2°C scenario scenario which follows the carbon emissions reduction pathway included in the IEA Energy Technology Perspectives ( [[#IEA--2017|IEA 2017]] ) by using the common framework ( [[#APERC--2019|APERC 2019]] ).

|-
| Low-Carbon Asia Research Project

| The low-carbon emission scenarios for several countries and cities in Asia were assessed by using the same framework ( [[#Matsuoka--2013|Matsuoka et al. 2013]] ). The mitigation activities were summarised into 10 actions toward Low Carbon Asia to show a guideline to plan and implement the strategies for an LCS in Asia ( [[#Low-Carbon%20Asia%20Research%20Project--2012|Low-Carbon Asia Research Project 2012]] ).

|-
| CLIMACAP–LAMP

| This is an inter-model comparison exercise that focused on energy and climate change mitigation in Latin America ( [[#Clarke--2016|Clarke et al. 2016]] ).

|-
| DDPP-LAC (Latin American Deep Decarbonisation Pathways project)

| Six countries in Latin America analysed the activities in agriculture, forestry and other land use (AFOLU) commonly (Bataille et al. 2020).

|-
| MILES (Modelling and Informing Low-Emission Strategies)

| This is an international research project which covers five countries and one region in order to build capacity and knowledge on low-emissions development strategies both at a national and global level, by investigating the concrete implications of INDCs for the low-carbon transformation by and beyond 2030 ( [[#Spencer--2015|Spencer et al. 2015]] ).

|}

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