Editing IPCC:AR6/WGIII/Chapter-7 (section)

==== 7.2.3.1 Global AFOLU CH 4 and N 2 O Emissions ====

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Using FAOSTAT data, the SRCCL estimated average CH 4 emissions from AFOLU to be 161.2 ± 43 MtCH 4 yr –1 for the period 2007–2016, representing 44% of total anthropogenic CH 4 emissions, with agriculture accounting for 88% of the AFOLU component ( [[#Jia--2019|Jia et al. 2019]] ). The latest data ( [[#FAO--2021a|FAO 2021a]] , 2020b) highlight a trend of growing AFOLU CH 4 emissions, with a 10% increase evident between 1990 and 2019, despite year-to-year variation. Forestry and other land use (FOLU) CH 4 emission sources include biomass burning on forest land and combustion of organic soils (peatland fires) ( [[#FAO--2020c|FAO 2020c]] ). The agricultural share of AFOLU CH 4 emissions remains relatively unchanged, with the latest data indicating agriculture to have accounted for 89% of emissions on average between 1990 and 2019. The SRCCL reported with ''medium evidence'' and ''high agreement'' that ruminants and rice production were the most important contributors to overall growth trends in atmospheric CH 4 ( [[#Jia--2019|Jia et al. 2019]] ). The latest data confirm this in terms of agricultural emissions, with agreement between databases that agricultural CH 4 emissions continue to increase and that enteric fermentation and rice cultivation remain the main sources (Figure 7.7). The proportionally higher emissions from rice cultivation indicated by EDGAR data compared to the other databases, may result from the use of a Tier 2 methodology for this source within EDGAR ( [[#Janssens-Maenhout--2019|Janssens-Maenhout et al. 2019]] ).

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[[File:3f7a2799eba95bc9c3f99e8531c30ff3 IPCC_AR6_WGIII_Figure_7_7.png]]

'''Figure 7.7 | Estimated global mean agricultural CH''' 4 '''(top), N''' 2 '''O (middle) and aggregated CH''' 4 '''and N''' 2 '''O (using CO''' 2 '''-eq according to GWP100 AR6 values).''' '''(Bottom) emissions for three decades according to EDGAR v6.0 (Crippa''' '''et al.''' '''2021), FAOSTAT ( [[#FAO--2021a|FAO 2021a]] ) and USEPA ( [[#USEPA--2019|USEPA 2019]] ) databases.''' Latest versions of databases indicate historic emissions to 2019, 2019 and 2015 respectively, with average values for the post–2010 period calculated accordingly. For CH 4 , emissions classified as ‘Other Ag.’ within USEPA data, are re-classified as ‘Agricultural Biomass Burning’. Despite CH 4 emissions from agricultural soils also being included, this category was deemed to principally concern biomass burning on agricultural land and classified accordingly. For N 2 O, emissions classified within EDGAR as direct and indirect emissions from managed soils, and indirect emissions from manure management are combined under ‘Agricultural Soils’. Emissions classified by FOASTAT as from manure deposition and application to soils, crop residues, drainage of organic soils and synthetic fertilisers are combined under ‘Agricultural Soils’, while emissions reported as ‘Other Ag.’ under USEPA data are re-classified as ‘Agricultural Biomass Burning’.

The SRCCL also noted a trend of increasing atmospheric N 2 O concentration, with ''robust evidence'' and ''high agreement'' that agriculture accounted for approximately two-thirds of overall global anthropogenic N 2 O emissions. Average AFOLU N 2 O emissions were reported to be 8.7 ± 2.5 MtN 2 O yr –1 for the period 2007–2016, accounting for 81% of total anthropogenic N 2 O emissions, with agriculture accounting for 95% of AFOLU N 2 O emissions ( [[#Jia--2019|Jia et al. 2019]] ). A recent comprehensive review confirms agriculture as the principal driver of the growing atmospheric N 2 O concentration ( [[#Tian--2020|Tian et al. 2020]] ). The latest FAOSTAT data ( [[#FAO--2020b|FAO 2020b]] , 2021a) document a 25% increase in AFOLU N 2 O emissions between 1990 and 2019, with the average share from agriculture remaining approximately the same (96%). Agricultural soils were identified in the SRCCL and in recent literature as a dominant emission source, notably due to nitrogen fertiliser and manure applications to croplands, and manure production and deposition on pastures ( [[#Jia--2019|Jia et al. 2019]] ; [[#Tian--2020|Tian et al. 2020]] ). There is agreement within latest data that agricultural soils remain the dominant source (Figure 7.7).

Aggregation of CH 4 and N 2 O to CO 2 equivalence (using GWP100 IPCC AR6 values), suggests that AFOLU emissions increased by 15% between 1990 and 2019, though emissions showed trend variability year to year. Agriculture accounted for 91% of AFOLU emissions on average over the period ( [[#FAO--2020b|FAO 2020b]] , 2021a). EDGAR ( [[#Crippa--2021|Crippa et al. 2021]] ), FAOSTAT ( [[#FAO--2021a|FAO 2021a]] ) and USEPA ( [[#USEPA--2019|USEPA 2019]] ) data suggest aggregated agricultural emissions (CO 2 -eq) to have increased since 1990, by 19% (1990–2019), 15% (1990–2019) and 21% (1990–2015) respectively, with all databases identifying enteric fermentation and agricultural soils as the dominant agricultural emissions sources.

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