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

== 4.1 Introduction ==

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The recent IPCC Report on Global Warming of 1.5°C (SR1.5) made clear that the next three decades are critical if we are to achieve the long-term mitigation goal of the Paris Agreement ( [[#IPCC--2018a|IPCC 2018a]] ). The present chapter assesses the literature on mitigation and development pathways over that timeframe, in the near (up to 2030) and mid-term (up to 2050).

It considers three questions: (i) Where are we heading now? That is, what is the current state of affairs with respect to climate mitigation and how did we get here? (ii) Where do we want to go? For example, what state of affairs would meet the objectives of the Paris Agreement and achieving the Sustainable Development Goals (SDGs)? and (iii) How do we bring about this shift? In other words, what interventions are at societies’ disposal to bring about the necessary change in an equitable manner?

'''Where are we heading now?''' Despite the drop in emissions due to the COVID-19 crisis, the gap between projected emissions based on Nationally Determined Contributions (NDCs) in 2030 and emissions pathways compatible with the long term temperature goal set in the Paris Agreement remains large (Section 4.2.2). In addition to this persistent emissions gap, we face an implementation gap, as current policies are insufficient to achieve mitigation targets in NDCs, and sufficient international support is not yet available to developing countries who have requested and quantified support needs. Continuing along a development pathway characterised by the same underlying drivers, structural obstacles and insufficient enabling conditions that led to high emissions will not address the problem ( ''robust evidence'' , ''h'' ''igh agreement'' ).

The analysis of the gap is conducted together with [[IPCC:Wg3:Chapter:Chapter-3|Chapter 3]] (Cross-Chapter Box 4 in this chapter). [[IPCC:Wg3:Chapter:Chapter-3|Chapter 3]] is working backward, assessing mitigation in the long term (beyond 2050 up to 2100) to draw the near- and mid-term implications of long-term temperature and mitigations goals. Chapter 4, on the other hand, works forward from current and planned mitigation (including NDCs) (Sections 4.2.1 and 4.2.2) and from current development paths to assess the implications for near- and mid-term greenhouse gases (GHG) emissions and development goals. Some countries, regions, cities, communities and non-state actors are taking leadership in implementing more ambitious action (Section 4.2.3). This chapter also assesses national low emission development strategies (Section 4.2.4).

'''Where do we want to go?''' Technical alternatives and policy options exist to bridge the emissions and implementation gaps, and the literature illustrates these with a wide range of accelerated techno-economic pathways that deepen decarbonisation closer to the pace and scale required ( [[#4.2.5|Section 4.2.5]] ), and examines their impacts on other development objectives ( [[#4.2.6|Section 4.2.6]] ). In practice, however, scaling up at the broader, deeper, and faster level required to meet climate goals while advancing other development objectives regularly faces prohibitive obstacles ( [[#4.2.7|Section 4.2.7]] ). Mitigation policies grafted on to existing development pathways are unlikely to achieve rapid and deep emission reductions.

Secondly, even if carefully designed, climate policies to accelerate mitigation may have adverse consequences for other development objectives. As a complement to mitigation action, taking action to shift development pathways towards sustainability broadens the range of mitigation options, while increasing the possibility to meet other development priorities at the same time ( ''medium evidence'' , ''h'' ''igh agreement'' ).

Development pathways and shifting them to increased sustainability are introduced in Chapter 1, and constitute a thread throughout the report (see ‘development pathways’ in Annex I: Glossary). The AR6 WGII Report highlights the related concept of ''climate resilient development pathways'' (AR6 WGII, Chapter 18). Cross-Chapter Box 5 in this chapter – on shifting sustainable pathway towards sustainability – elaborates on the concept. The influence of development pathways on emissions and mitigative capacity is discussed in Chapter 2. [[IPCC:Wg3:Chapter:Chapter-3|Chapter 3]] assesses modelling of shifts in development pathways, illustrated by the illustrative mitigation pathway called ‘shifting pathways’. The importance of behavioural change as societies make decisions that intentionally shift their future development pathway is emphasised in Chapter 5. The systems Chapters (6–12) take sectoral perspectives, while pathways that are sustainable are the specific focus of Chapter 17.

'''How can one shift development pathway and accelerate mitigation?''' The literature does not provide a complete handbook for shifting development pathways and accelerating mitigation. The literature does, however, shed light on some of the underlying dynamics. Shifting development pathways can be necessitated by the existence of pervasive obstacles that prove prohibitive to reaching mitigation and other development objectives ( [[#4.2.7|Section 4.2.7]] ). Deliberate measures taken to facilitate the shifting of development pathways and accelerated mitigation involve putting in place key enabling conditions that help overcome those obstacles (Figure 4.6) – improving governance and institutional capacity, fostering behavioural change and technological innovation, designing and implementing adequate policy, and finance. Just transitions, while they will differ by context, are critical to identifying and avoiding or addressing inequitable distributive consequences ( ''robust evidence'' , ''h'' ''igh agreement'' ).

Enabling conditions necessary to accelerate mitigation and shift development pathways are discussed in depth in Chapters 5, 13, 14, 15 and 16. In addition, Chapters 13 and 14 detail the policy instruments that could help shift development pathways and accelerate the scale and pace of mitigation, while [https://www.ipcc.ch/report/ar6/wg3/chapter/chapter-4 Chapter 4] describes those in broad strategies terms. [[IPCC:Wg3:Chapter:Chapter-13|Chapter 13]] adds more texture on institutional and governance machinery; policy choice, design and implementation; as well as policy formulation processes, actors and structure across scales.

Since development pathways and mitigation options depend to large extent on national objectives and circumstances, this chapter is primarily concerned with literature at national level (or in the case of the European Union, at regional level), while [[IPCC:Wg3:Chapter:Chapter-3|Chapter 3]] is primarily concerned with literature at global scale. The national scale selected in this chapter requires attention as national mitigation pathways cannot be linked directly to global mitigation goals (Box 4.2). This chapter is also concerned mostly with economy-wide development and mitigation pathways, as distinct from detailed sectoral work that is assessed in the systems Chapters 6 to 12. The present chapter also assesses literature on non-state action.

[https://www.ipcc.ch/report/ar6/wg3/chapter/chapter-4 Chapter 4] draws on five major strands of literature: (i) an emerging literature on development pathways – conceptual, empirical, and model-based, including at the national and sub-national scales; (ii) a rapidly expanding, model-based, literature on mitigation pathways in the near- and mid-term ( [[#Lepault--2021|Lepault and Lecocq 2021]] ); (iii) studies of NDCs and mid-century strategies; (iv) a broader literature on transformation and shifts in development pathways, including from non-climate literatures; and (v) a significant literature on equity, including just transitions. This is supported by a database of country-level mitigation scenarios at country level assembled for the preparation of this chapter (Annex III, Table I.10 and I.11).

The chapter builds on past IPCC reports. In AR5, all mitigation pathways were assessed in a single chapter (Clarke et al. 2014), which focused mostly on the long term. IPCC Special Report on Global Warming of 1.5°C (SR1.5) included a chapter on mitigation pathways compatible with the temperature goal in the Paris Agreement ( [[#Rogelj--2018a|Rogelj et al. 2018a]] ), mostly at the global level. It also considered strengthening mitigation ( [[#de%20Coninck--2018|de Coninck et al. 2018]] ) in the context of poverty, inequality and sustainable development ( [[#Roy--2018|Roy et al. 2018]] ). Development pathways have also been explored, albeit less frequently, in past IPCC reports starting with the Special Report on Emissions Scenarios (Nakicenovic et al. 2000). Some early framing of development pathways was included in the Third Assessment Report (Banuri et al. 2001), further developed in the Fourth Assessment Report ( [[#Sathaye--2007|Sathaye et al. 2007]] ). An extended discussion of climate change and equity was conducted in AR5 (Fleurbaey et al. 2014).

[https://www.ipcc.ch/report/ar6/wg3/chapter/chapter-4 Chapter 4] examines mitigation within the broader context of development pathways, and examines how shifting development pathways can have a major impact on mitigative capacity and broadening mitigation options. It is organised as follows.

Section 4.2 demonstrates that collective mitigation actions fall short of pathways that keep in reach the Paris temperature goals in the long term. [[#4.3|Section 4.3]] introduces development pathways (given its relative novelty in IPCC assessments), considers the implications of mitigation for development and vice versa, and articulates an approach on ''both'' accelerating mitigation ''and'' shifting development pathways.

[[#4.4|Section 4.4]] discusses how to shift development pathway and accelerate the scale and pace of mitigation, what levers are available to policymakers, and how policies may intersect with adaptation goals. It points out that development pathways also drive adaptation and adaptative capacity, and discusses various risks associated with shifting development pathways and accelerated mitigation strategies.

Finally, equity and just transitions are recurring themes in the chapter, specifically in relation to accelerating mitigation and shifting development pathways toward sustainability. In Section 4.2.2.7, equity is discussed in the context of Parties’ assertions regarding the fairness of their NDCs, alongside reflections from academic scholarship on the ethical underpinnings of these assertions and of various quantitative analyses of equitable effort-sharing. [[#4.2.6|Section 4.2.6]] discusses certain distributional implications of domestic mitigation efforts, such as shifts in employment. Sections 4.2.7 and 4.3 note the relevance of potential distributional impacts as an obstacle to climate action, as well as the inequitable distribution of decision-making authority. Finally, [[#4.5|Section 4.5]] recognises the structural relationship between equity and climate, explores just transitions as an international focal point tying together social movements, trade unions, and other stakeholders, and thus an instrumental role in establishing consensus.

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