Editing IPCC:AR6/WGIII/Chapter-2 (section)

=== 2.2.4 Sectoral GHG Emissions Trends ===

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In 2019, 34% (20 GtCO 2 -eq) of the 59 GtCO 2 -eq GHG emissions came from the energy sector, 24% (14 GtCO 2 -eq) from industry, 22% (13 GtCO 2 -eq) from AFOLU, 15% (8.7 GtCO 2 -eq) from transport and 6% (3.3 GtCO 2 -eq) from buildings (Figure 2.12). The relative size of each sector depends on the exact definition of sector boundaries ( [[#de%20la%20Rue%20du%20Can--2015|de la Rue du Can et al. 2015]] ; [[#Lamb--2021b|Lamb et al. 2021b]] ). The largest individual subsector contributing to global GHG emissions in 2019 was electricity and heat generation at 14 GtCO 2 -eq. This subsector can be reallocated to consuming sectors as indirect (scope 2) emissions to emphasise the role of final energy demand and demand-side solutions in climate change mitigation ( [[#Creutzig--2018|Creutzig et al. 2018]] ) (Chapter 5). This increases the emission share of the industry sector to 34% and of the buildings sector to 16%.

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'''Figure 2.12''' '''|''' '''Total anthropogenic direct and indirect GHG emissions for the year 2019 (in GtCO''' 2 '''-eq) by sector and subsector.''' Direct emissions estimates assign emissions to the sector in which they arise (scope 1 reporting). Indirect emissions – as used here – refer to the reallocation of emissions from electricity and heat to the sector of final use (scope 2 reporting). Note that cement refers to process emissions only, as a lack of data prevents the full reallocation of indirect emissions to this sector. More comprehensive conceptualisations of indirect emissions including all products and services (scope 3 reporting) are discussed in [[#2.3|Section 2.3]] of this chapter. Emissions are converted into CO 2 -equivalents based on global warming potentials with a 100-year time horizon (GWP100) from the IPCC Sixth Assessment Report. Percentages may not add up to 100 across categories due to rounding at the second significant digit. Source: based on [[#Lamb--2021b|Lamb et al. (2021b)]] ; data: [[#Minx--2021|Minx et al. (2021)]] .

Average annual GHG emissions growth has been fastest in the transport sector with about 1.8% for the most recent period 2010–2019, followed by direct emissions in the industry sector (1.4%) and the energy sector (1%) (Figure 2.13). This is different to growth patterns observed in the previous decade as reported in AR5 (IPCC 2014a; Blanco et al. 2014). Between 2000 and 2009 fastest GHG emissions growth was observed for industry with 3.4% followed by the energy sector with 2.3%. GHG emissions growth in the transport sector has been stable across both periods at about 1.8%, while direct building emissions growth averaged below 1% during 2010–2019. Ranking of high-emitting subsectors by direct emissions highlights the importance of CO 2 emissions from LULUCF (6.6 GtCO 2 -eq; but with low confidence in magnitude and trend), road transport (6.1 GtCO 2 -eq), metals (3.1 GtCO 2 -eq), and other industry (4.4 GtCO 2 -eq). Overall, some of the fastest growing sources of subsector emissions from 2010 to 2019 have been international aviation (+3.4%), [[#footnote-004|10]] domestic aviation (+3.3%), inland shipping (+2.9%), metals (+2.3%), international shipping (+1.7%), and road transport (+1.7%).

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'''Figure 2.13''' '''|''' '''Total annual anthropogenic GHG emissions by major economic sector and their underlying trends by region. Panel (a):''' Trends in total annual anthropogenic GHG emissions (in GtCO 2 -eq yr –1 ) by major economic sector. '''Panel (b):''' Trends in total annual anthropogenic GHG emissions (in GtCO 2 -eq yr –1 ) by major economic sector and region. Panels c and d: Largest subsectoral changes in GHG emissions for the reporting period 2010–2019 in relative (% annual change) and absolute terms (GtCO 2 -eq yr –1 ). Emissions are converted into CO 2 -equivalents based on global warming potentials with a 100-year time horizon (GWP100) from the IPCC Sixth Assessment Report. Source: based on [[#Lamb--2021b|Lamb et al. (2021b)]] ; Data: [[#Crippa--2021|Crippa et al. (2021)]] ; [[#Minx--2021|Minx et al. (2021)]] .

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