Editing IPCC:AR6/WGIII/Chapter-11 (section)

==== 11.4.2.1 Central Results From (Top-down) Scenarios Analysis and Illustrative Mitigation Pathways Discussion ====

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[[IPCC:Wg3:Chapter:Chapter-3|Chapter 3]] conducted a comprehensive analysis of scenarios based on IAMs. The resulting database comprises more than 1000 model-based scenarios published in the literature. The scenarios span a broad range along temperature categories from rather baseline-like scenarios to the description of pathways that are compatible with the 1.5°C target. Comparative discussion of scenarios allows some insights with regard to the relevance of mitigation strategies for the industry sector (Figure 11.11).

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'''Figure 11.11 Industrial final energy (top left), CO''' 2 '''emissions (top middle), energy intensity (bottom left), carbon intensity (top right), share of electricity (bottom middle), and share of gases (bottom right).''' Energy intensity is final energy per unit of GDP. Carbon intensity is CO 2 emissions per EJ of final energy. The first four indicators are indexed to 2019, where values less than 1 indicate a reduction. Industrial-sector CO 2 emissions include fuel-combustion emissions only. Boxes indicate the interquartile range, the median is shown with a horizontal black line, while vertical lines show the 5 to 95% interval. Source: data are from the AR6 database; only scenarios that pass the vetting criteria are included ( [[IPCC:Wg3:Chapter:Chapter-3#3.2|Section 3.2]] ).

The main results from the [[IPCC:Wg3:Chapter:Chapter-3|Chapter 3]] analysis from an industry perspective are:

• While all scenarios show a decline in energy and carbon intensity over time, final energy demand and associated industry-related CO 2 emissions increase in many scenarios. Only ambitious scenarios (category C1) show significant reduction in final energy demand in 2030, more or less constant demand in 2050, but increasing demand in 2100, driven by growing material use throughout the 21st century. While carbon intensity shrinks over time, energy related CO 2 -emissions decline after 2030 even in less ambitious scenarios, but particularly in those pursuing a temperature incr ease below 2°C. Reduction of CO 2 emissions in the sector are achieved through a combination of technologies which includes nearly all options that have been discussed in this chapter (Sections 11.3 and 11.4.1). However, there are big differences with regard to the intensity by which the various options are implemented in the scenarios. This is particularly true for CCS for industrial applications and material efficiency and material demand management (i.e., service demand, service product intensity). The latter options are still under-represented in many global IAMs.

'''•''' There are only a few scenarios which allow net-negative CO 2 emissions for the industry for the second half of the century, while most scenarios assessed (including the majority of 1.5°C scenarios) end up with still significant positive CO 2 emissions. In comparison to the whole system most scenarios expect a slower decrease of industry-rel ated emissions.

• There is a great – up to a factor of two – difference in assumptions about the GHG mitigation potential associated with different carbon cost levels between IAMs and sector-specific industry models. Consequently, IAMs pick up mitigation options slower or later (or not at all) than models which are more technologically detailed. Due to their top-down perspective IAMs to date have not been able to represent the high complexity of industries in terms of the broad variety of technologies and processes (particularly circularity aspects) and to fully reflect the dynamics of the sector. In addition, as energy and carbon price elasticities are still not completely understood, primarily cost-driven models have their limitations. However, there are several ongoing activities to bring more engineering knowledge and technological details into the IAM models (Kermel i et al. 2021).

In addition to the more aggregated discussion, the IAMs illustrative mitigation pathways (IMPs) allow a deeper look into the transformation pathways related to the scenarios. For the illustrative mitigation pathways (IMPs) approach, sets of scenarios have been selected which represent different levels of GHG mitigation ambitions, scenarios which rely on different key strategies or even exclude some mitigation options, represent delayed actions or SDG-oriented pathways. For more detailed information about the selection see [[IPCC:Wg3:Chapter:Chapter-3#3.3.2|Section 3.3.2]] . compares for a selected number of key variables the results of IMPs and puts them in the context of the whole sample of IAMs scenario results for three temperature categories.

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'''Figure 11.12 | Comparison of industry-sector-related CO''' 2 '''emissions (including process emissions), final energy demand, share of electricity and hydrogen in the final energy mix, and industrial carbon capture and storage (CCS) for different mitigation scenarios representing illustrative mitigation pathways and the full sample of integrated assessment models (IAM) scenario results for three temperature categories (figure based on scenario database).''' Indicators in the Illustrative Mitigation Pathways (lines) and the 5–95% range of reference, 1.5°C and 2°C scenarios (shaded areas). The selected IMPs reflect the following characteristics: opportunities for reducing demand (IMP-LD; low demand), the role of deep renewable energy penetration and electrification (IMP-Ren; renewables), extensive use of carbon dioxide removal (CDR) in the industry and the energy sectors to achieve net-negative emissions (IMP-Neg), insights into how shifting development can lead to deep emission reductions and achieve sustainable development goals (IMP-SP; shifting pathways), and insights into how slower short-term emissions reductions can be compensated by very fast emission reductions later on (IMP-GS; gradual strengthening). Furthermore, two scenarios were selected to illustrate the consequences of current policies and pledges; these are CurPol (Current Policies) and ModAct (Moderate Action), and are referred to as Pathways Illustrative of Higher Emissions. Source: data are from the AR6 database; only scenarios that pass the vetting criteria are included ( [[IPCC:Wg3:Chapter:Chapter-3#3.2|Section 3.2]] ).

With growing mitigation ambition final energy demand is significantly lower in comparison of a current policy pathway (CurPol) and a scenario that explores the impact of further moderate actions (ModAct). Based on the underlying assumptions, scenarios IMP-SP and IMP-LD are characterised by the lowest final energy demand, triggered by high energy efficiency improvement rates as well as additional demand side measures, while a scenario with extensive use of CDR in the industry and the energy sectors to achieve net-negative emissions (IMP-Neg) leads to a significant increase in final energy demand. Scenario IMP-GS represents a pathway where mitigation action is gradually strengthened by 2030 compared to pre-COP 26 Nationally Determined Contributions (NDCs) shows the lowest final energy demand. All ambitious IMPs show substantially increasing contributions from electricity, with electricity’s end-use share more than doubling for some of them by 2050 and more than tripling by 2100. The share of hydrogen shows a flatter curve for many scenarios, reaching 5% (IMP-Ren) in 2050 and up to 20% in 2100 for some scenarios (Ren, LD). Those scenarios that have a strong focus on renewable energy electrification show high shares of hydrogen in the sector. In comparison to sector-specific and national studies which show typically a range between 5 and 15% by 2050, many IAM IMPs expect hydrogen to play a less important role. Results for industrial CCS show a broad variety of contributions, with the GS scenario (where hydrogen is not relevant as a mitigation option) representing the upper bound to 2050, with almost 2 GtCO 2 yr –1 captured and stored by 2050. Beyond 2050 the upper bound is associated with scenario IMP-Neg associated with extensive use of CDR in the industry and energy sectors to achieve net-negative emissions in the second half of the century – more than 6 GtCO 2 yr –1 is captured and stored in 2100 (this represents roughly 60% of 2018 direct CO 2 emissions of the sector).

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