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

=== 11.2.2 New Trends in Emissions ===

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GHG emissions attributable to the industrial sector (see Chapter 2) in 2019 originate from industrial fuel combustion (7.1 GtCO 2 -eq directly and about 5.9 Gt indirectly from electricity and heat generation [[#footnote-011|16]] ); industrial processes (4.5 GtCO 2 -eq) and products use (0.2 Gt), as well as from waste (2.3 Gt) (Figure 11.4a,b). Overall industrial direct GHG emissions amount to 14.1 GtCO 2 -eq (Figure 11.4c and Table 11.1), and scales up to 20 GtCO 2 -eq after indirect emissions are added, [[#footnote-010|17]] putting industry (24%, direct emissions) second after the energy sector in total GHG emissions and lifting it to the leading position after indirect emissions are allocated (34% in 2019). [[#footnote-009|18]] The corresponding shares for 1990–2000 were 21% for direct emissions and 30% for both direct and indirect ( [[#Crippa--2021|Crippa et al. 2021]] ; [[#Lamb--2021|Lamb et al. 2021]] ; [[#Minx--2021|Minx et al. 2021]] ). As the industrial sector is expected to decarbonise slower than other sectors it will keep this leading position for the coming decades ( [[#IEA--2021a|IEA 2021a]] ). In 2000–2010, total industrial emissions grew faster (3.8% yr –1 ) than in any other sector (see Chapter 2), mostly due to the dynamics shown by basic materials extraction and production. Industry contributed nearly half (45%) of overall incremental global GHG emissions in the 21st century.

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'''Figure 11.4 | Industrial sector direct global greenhouse gas (GHG) emissions.''' Source: calculated based on emissions data from [[#Crippa--2021|Crippa et al. (2021)]] and [[#Minx--2021|Minx et al. (2021)]] . Indirect emissions were assessed using [[#IEA--2021b|IEA (2021b)]] . For (e): [[#Cao--2020|Cao et al. (2020)]] ; IEA (2020b, 2021a); [[#GCCA--2021a|GCCA (2021a)]] ; [[#International%20Aluminium%20Institute--2021a|International Aluminium Institute (2021a)]] ; and [[#Wang--2021|Wang et al. (2021)]] .

Industrial sector GHG emissions accounting is complicated by carbon storage in products ( [[#Levi--2018|Levi and Cullen 2018]] ). About 35% of chemicals’ mass is CO 2 , which is emitted at use stage – decomposition of fertilisers, or plastic waste incineration ( [[#Saygin--2021|Saygin and Gielen 2021]] ), and sinks. Recarbonation and mineralisation of alkaline industrial materials and wastes (also known as the ‘sponge effect’) provide 0.6–1 GtCO 2 yr –1 uptake by cement-containing products [[#footnote-008|19]] ( [[#Cao--2020|Cao et al. 2020]] ; [[#Guo--2021|Guo et al. 2021]] ); see [[#11.3.6|Section 11.3.6]] for further discussion in decarbonisation context.

In 1970–1990, industrial direct combustion-related emissions were growing modestly, and in 1990–2000 even switched to a slowly declining trend, steadily losing their share in overall industrial emissions. Electrification was the major driver behind both indirect and total industrial emissions in those years. This quiet evolution was interrupted in the beginning of the 21st century, when total emissions increased by 60–68% depending on the metric applied (the fastest growth ever seen). In 2000–2019 iron, steel and cement absolute GHGs increased more than any other period in history ( [[#Bashmakov--2021|Bashmakov 2021]] ). Emissions froze temporarily in 2014–2016, partly in the wake of the financial crisis, but returned to their growth trajectory in 2017–2019 (Figure 11.4a).

The largest incremental contributors to industrial emissions in 2010–2019 were industrial processes at 40%, then indirect emissions (25%), and only then direct combustion (21%), followed by waste (14%; Figure 11.4). Therefore, to stop emission growth and to switch to a zero-carbon pathway more mitigation efforts should be focused on industrial processes, product use and waste decarbonisation, along with the transition to low-carbon electrification ( [[#Hertwich--2020|Hertwich et al. 2020]] ).

Basic materials production dominates both direct industrial GHG emissions (about 62%, waste excluded) [[#footnote-007|20]] as well as direct industrial CO 2 emissions (70%), led by iron and steel, cement, chemicals, and non-ferrous metals (Figure 11.4e). Basic materials also contribute 60% to indirect emissions. In a zero-carbon power world, with industry lagging behind in the decarbonisation of high-temperature processes and feedstock, it may replace the energy sector as the largest generator of indirect emissions embodied in capital stock. [[#footnote-006|21]] According to [[#Circle%20Economy--2020|Circle Economy (2020)]] and [[#Hertwich--2020|Hertwich et al. (2020)]] , GHG emissions embodied in buildings and infrastructure, machinery and transport equipment exceed 50% of their present carbon footprint.

In 1970–2000, direct GHG emissions per unit of energy showed a steady decline interrupted by noticeable growth in 2001–2018 driven by the fast expansion of steel and cement production (Figure 11.5; [[#IEA--2021a|IEA 2021a]] ). Non-energy-related GHG emissions per unit of extracted materials decline continuously, as the share of not carbon intensive building materials (aggregates and sand) grows.

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'''Figure 11.5 | Industrial sector greenhouse gas (GHG) emissions in 10 world regions (''' '''1990–2019''' ''').''' Source: calculated based on emissions data from [[#Crippa--2021|Crippa et al. (2021)]] . Indirect emissions were assessed using [[#IEA--2021b|IEA (2021b)]] .

|Iron and steel carbon intensity stagnated in 1995–2015 due to rapid growth in carbon-intensive production in some countries ( [[#Wang--2021|Wang et al. 2021]] ). For aluminium carbon intensity declined in 2010–2019 by only 2% ( [[#International%20Aluminium%20Institute--2021a|International Aluminium Institute 2021a]] ). The carbon intensity of cement-making since 2010 is down by only 4%. In 1990–2019 it fell by 19.5%, mostly due to energy efficiency improvements (by 18.5%) as the carbon intensity of the fuel mix declined only by 3% ( [[#GCCA--2021b|GCCA 2021b]] ). Historical analysis shows the carbon intensity of steel production has declined with ‘stop and go’ patterns in 50–60-year cycles, reflective of the major jumps in best available technology (BAT). From 1900 to 1935 and from 1960 to 1990 specific scope 1 + 2 + 3 emissions fell by 1.5–2.5 tCO 2 per tonne, or as much as needed now to achieve net zero. While historical declines were mostly due to commissioning large capacities with new technologies, with total emissions growing, by 2050 and beyond the decline will likely materialise via new ultra-low emission capacity replacements pushing absolute emissions to net zero ( [[#Bataille--2021b|Bataille et al. 2021b]] ).

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