Editing IPCC:AR6/WGIII/Chapter-4 (section)

=== 4.2.4 Mid-century Low-emission Strategies at the National Level ===

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An increasing amount of literature describes mitigation pathways for the mid-term (up to 2050). We assess literature reflecting on the UNFCCC process ( [[#4.2.4.1|Section 4.2.4.1]] ), other official plans and strategies ( [[#4.2.4.2|Section 4.2.4.2]] ) and academic literature on mid-century low-emission pathways at the national level ( [[#4.2.4.3|Section 4.2.4.3]] ). After the Paris Agreement and the IPCC SR1.5 Report, the number of academic papers analysing domestic emission pathways compatible with the 1.5°C limit has been increasing. Governments have developed an increasing number of mitigation strategies up to 2050. Several among these strategies aim at net zero CO 2 or net zero GHG, but it is not yet possible to draw global implications due to the limited size of sample ( ''limited evidence'' , ''limi'' ''ted agreement'' ).

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'''Box 4.2 | Direct Links Between an Individual Actor’s Mitigation Efforts in the Near Term and Global Temperature Goals in the Long Term Cannot be Inferred: Making direct links requires clear distinctions of spatial and temporal scales ( [[#Robertson--2021|Robertson 2021]] ; [[#Rogelj--2021|Rogelj et al. 2021]] ) and explicit treatment of ethical judgements made ( [[#Klinsky--2017a|Klinsky et al. 2017a]] ; [[#Holz--2018|Holz et al. 2018]] ; [[#Klinsky--2018|Klinsky and]] [[#Winkler--2018|Winkler 2018]] ; [[#Rajamani--2021|Rajamani et al. 2021]] )'''

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The literature frequently refers to ''national'' mitigation pathways up to 2030 or 2050 using long-term temperature limits in the Paris Agreement (i.e., ‘2°C’ or ‘1.5°C scenario’). Without additional information, such denomination is incorrect. Working Group I reaffirmed ‘with high confidence the AR5 finding that there is a near-linear relationship between cumulative anthropogenic CO 2 emissions and the global warming they cause’ (WGI SPM AR6). It is not the function of any single country’s mitigation efforts, nor any individual actor’s. Emission pathways of ''individual'' countries or sectors in the near to mid-term can only be linked to a long-term temperature with additional assumptions specifying (i) the GHG emissions and removals of other countries up the mid-term; and (ii) the GHG emissions and removals of all countries beyond the near and mid-term. For example, a national mitigation pathway can be labelled ‘2°C compatible’ if it derives from a global mitigation pathway consistent with 2°C via an explicit effort sharing scheme across countries (Sections 4.2.2.6 and 4.5).

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==== 4.2.4.1 GHG Mitigation Target Under UNFCCC and Paris Agreement ====

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The Paris Agreement requests that Parties should strive to formulate and communicate long-term low GHG development strategies by 2020. (Note that by ‘long-term’, the UNFCCC means 2050, which is the end point of the ‘mid-term’ horizon range in the present report.) As of August 25, 2021, 31 countries and the European Union had submitted low-emissions development strategies (LEDS) (Table 4.5).

By 2018, most long-term strategies targeted 80% emissions reduction in 2050 relative to a reference (1990, 2000 or 2005). After IPCC SR1.5 was published, the number of the countries aiming at net zero CO 2 or GHG emissions has been increasing. [[#footnote-000|6]]

'''Table 4.5 | Countries having submitted long-term low-GHG emission development strategy (as of 25 August 2021).'''

{| class="wikitable"
|-
! Country

! Date submitted

! GHG reduction target

|-
| USA

| Nov. 16, 2016

| 80% reduction of GHG in 2050 compared to 2005 level

|-
| Mexico

| Nov. 16, 2016

| 50% reduction of GHG in 2050 compared to 2000 level

|-
| Canada

| Nov. 17, 2016

| 80% reduction of GHG in 2050 compared to 2005 level

|-
| Germany

| Nov. 17, 2016

Rev. Apr. 26, 2017

Rev. May 4, 2017

| GHG neutrality by 2050

(Old target: 80–95% reduction of GHG in 2050 compared to 1990 level)

|-
| France

| Dec. 28, 2016

Rev. Apr. 18, 2017

Rev. Feb. 8, 2021

| Achieving net zero GHG emissions by 2050

(Old target: 75% reduction of GHG in 2050 compared to 1990 level)

|-
| Benin

| Dec. 12, 2016

| Resilient to climate change and low-carbon intensity by 2025

|-
| Czech Republic

| Jan. 15, 2018

| 80% reduction of GHG in 2050 compared to 1990 level

|-
| UK

| April 17, 2018

| 80% reduction of GHG in 2050 compared to 1990 level

|-
| Ukraine

| July 30, 2018

| 66–69% reduction of GHG in 2050 compared to 1990 level

|-
| Republic of the Marshall Islands

| Sept. 25, 2018

| Net zero GHG emissions by 2050

|-
| Fiji

| Feb. 25, 2019

| Net zero carbon by 2050 as central goal, and net negative emissions in 2041 under a Very High Ambition scenario

|-
| Japan

| June 26, 2019

| 80% reduction of GHG in 2050, and decarbonised society as early as possible in the 2nd half of 21st century

|-
| Portugal

| Sept. 20, 2019

| Carbon neutrality by 2050

|-
| Costa Rica

| Dec. 12, 2019

| Decarbonised economy with net zero emissions by 2050

|-
| European Union

| March 6, 2020

| Net zero GHG emissions by 2050

|-
| Slovakia

| March 30, 2020

| Climate neutrality by 2050, with decarbonisation targets implying reduction of at least 90% compared to 1990 (not taking into account removals)

|-
| Singapore

| March 31, 2020

| Halving emissions from its peak to 33 MtCO 2 -eq by 2050, with a view to achieving net zero emissions as soon as viable in the second half of the century

|-
| South Africa

| Sep. 23, 2020

| Net zero carbon economy by 2050

|-
| Finland

| Oct. 5, 2020

| Carbon neutrality by 2035; 87.5–90% reduction of GHG in 2050 to 1990 level (excluding land use sector)

|-
| Norway

| Nov. 25, 2020

| Being a low-emission society by 2050

|-
| Latvia

| Dec. 9, 2020

| Climate neutrality by 2050 (non-reducible GHG emissions are compensated by removals in the LULUCF sector)

|-
| Spain

| Dec. 10, 2020

| Climate neutrality by 2050

|-
| Belgium

| Dec. 10, 2020

| Carbon neutrality by 2050 (Walloon Region); Full climate neutrality (Flemish Region), and the European target of carbon neutrality by 2050 (Brussels-Capital Region)

|-
| Austria

| Dec. 11, 2020

| Climate-neutral by no later than 2050

|-
| Netherlands

| Dec. 11, 2020

| Reduction of GHG emissions by 95% by 2050 compared to 1990 level.

|-
| Sweden

| Dec. 11, 2020

| Zero net emissions of GHG into the atmosphere latest by 2045

|-
| Denmark

| Dec. 30, 2020

| Climate neutrality by 2050

|-
| Republic of Korea

| Dec. 30, 2020

| Carbon neutrality by 2050

|-
| Switzerland

| Jan. 28, 2021

| 2050 net zero GHG

|-
| Guatemala

| July 6, 2021

| 59% reduction of projected emissions by 2050

|-
| Indonesia

| July 22, 2021

| 540 MtCO 2 -eq by 2050, and with further exploring opportunity to rapidly progress towards net zero emission in 2060 or sooner

|-
| Slovenia

| Aug. 23, 2021

| Net zero emissions or climate neutrality by 2050

|}

‘rev.’ = ‘date revised’

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==== 4.2.4.2 Other National Emission Pathways to Mid-century ====

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At the 2019 Climate Action Summit, 77 countries indicated their aim to reach net zero CO 2 emissions by 2050, more the number of countries having submitted LEDS to the UNFCCC. Table 4.6 lists the countries that have a national net zero by 2050 target in laws, strategies or other documents ( [[#The%20Energy%20and%20Climate%20Intelligence%20Unit--2019|The Energy and Climate Intelligence Unit 2019]] ). Bhutan and Suriname already have achieved net negative emissions. France second ‘low-carbon national strategy’ adopted in 2020 has an objective of GHG neutrality by 2050. Net zero is also the basis of the recent revision of the official notional price of carbon for public investment in France ( [[#Quinet--2019|Quinet et al. 2019]] ). The Committee on Climate Change of the UK analyses sectoral options and concludes that delivering net zero GHG by 2050 is technically feasible but highly challenging ( [[#Committee%20on%20Climate%20Change--2019|Committee on Climate Change 2019]] ). For Germany, three steps to climate neutrality by 2050 are introduced: first, a 65% reduction of emissions by 2030; second, a complete switch to climate-neutral technologies, leading to a 95% cut in emissions, all relative to 1990 levels by 2050; and third balancing of residual emissions through carbon capture and storage (Prognos et al. 2020). In addition to the countries in Table 4.6, EU reported the net zero GHG emission pathways by 2050 under Green Deal ( [[#European%20Commission--2019|European Commission 2019]] ). China and South Korea, have made announcements of carbon neutrality before 2060 and net zero GHG emission by 2050, respectively ( [[#UN--2020a|UN 2020a]] ,b). In the case of Japan, the new target to net zero GHG emission by 2050 was announced in 2020 ( [[#UN--2020c|UN 2020c]] ). As of August 25, 2021, a total 121 countries participate in the ‘Climate Ambition Alliance: Net Zero 2050’, together with businesses, cities and regions.

'''Table 4.6 | Countries with a national net zero CO''' 2 '''or GHG target by 2050 (as of 2''' '''5 August 2021).'''

{| class="wikitable"
|-
! Country

! Target year

! Target status

! Source

|-
| Suriname

|
| Achieved

| Suriname INDC

|-
| Bhutan

|
| Achieved

| Royal Government of Bhutan National Environment Commission

|-
| Germany

| 2045

| In Law

| KSG

|-
| Sweden

| 2045

| In Law

| Climate Policy Framework

|-
| European Union

| 2050

| In Law

| European Climate Law

|-
| Japan

| 2050

| In Law

| Japan enshrines PM Suga’s 2050 carbon neutrality promise into law

|-
| United Kingdom

| 2050

| In Law

| The Climate Change Act

|-
| France

| 2050

| In Law

| Energy and Climate Law

|-
| Canada

| 2050

| In Law

| Canadian Net Zero Emissions Accountability Act

|-
| Spain

| 2050

| In Law

| New Law

|-
| Denmark

| 2050

| In Law

| The Climate Act

|-
| New Zealand

| 2050

| In Law

| Zero Carbon Act

|-
| Hungary

| 2050

| In Law

| Climate Ambition Alliance: Net Zero 2050

|-
| Luxembourg

| 2050

| In Law

| Climate Ambition Alliance: Net Zero 2050

|-
| South Korea

| 2050

| Proposed Legislation

| Speeches and Statements by the President

|-
| Ireland

| 2050

| Proposed Legislation

| Climate Action and Low Carbon Development (Amendment) Bill 2021

|-
| Chile

| 2050

| Proposed Legislation

| Chile charts path to greener, fairer future

|-
| Fiji

| 2050

| Proposed Legislation

| Draft Climate Law

|}

Note: In addition to the above list, the numbers of ‘In Policy Document’ and ‘Target Under discussion’ as Target status are 37 countries and 79 countries, respectively.

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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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