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

== 7.1 Introduction ==

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=== 7.1.1 Key Findings from Previous Reports ===

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Agriculture, Forestry and Other Land Uses (AFOLU) is unique due to its capacity to mitigate climate change through greenhouse gas (GHG) emission reductions, as well as enhance removals ( [[#IPCC--2019|IPCC 2019]] ). However, despite the attention on AFOLU since early 1990s it was reported in the IPCC Special Report on Climate Change and Land (SRCCL) as accounting for almost a quarter of anthropogenic emission ( [[#IPCC--2019|IPCC, 2019]] ), with three main GHGs associated with AFOLU; carbon dioxide (CO 2 ), methane (CH 4 ) and nitrous oxide (N 2 O). Overall emission levels had remained similar since the publication of AR4 ( [[#Nabuurs--2007|Nabuurs et al. 2007]] ). The diverse nature of the sector, its linkage with wider societal, ecological and environmental aspects and the required coordination of related policy, was suggested to make implementation of known and available supply- and demand-side mitigation measures particularly challenging ( [[#IPCC--2019|IPCC 2019]] ). Despite such implementation barriers, the considerable mitigation potential of AFOLU as a sector on its own and its capacity to contribute to mitigation within other sectors was emphasised, with land-related measures, including bioenergy, estimated as capable of contributing between 20% and 60% of the total cumulative abatement to 2030 identified within transformation pathways ( [[#IPCC--2018|IPCC 2018]] ). However, the vast mitigation potential from AFOLU initially portrayed in literature and in Integrated Assessment Models (IAMs), as explored in the IPCC Special Report on Climate Change of 1.5°C (SR1.5), is being questioned in terms of feasibility ( [[#Roe--2021|Roe et al. 2021]] ) and a more balanced perspective on the role of land in mitigation is developing, while at the same time, interest by private investors in land-based mitigation is increasing fast.

The SRCCL ( [[#IPCC--2019|IPCC 2019]] ) outlined with ''medium evidence'' and ''medium agreement'' that supply-side agriculture and forestry measures had an economic (at USD100 tCO 2 -eq –1 ) mitigation potential of 7.2–10.6 GtCO 2 -eq –1 in 2030 (using GWP100 and multiple IPCC values for CH 4 and N 2 O) of which about a third was estimated as achievable at &lt;USD20 tCO 2 -eq –1 . Agricultural measures were reported as sensitive to carbon price, with cropland and grazing land soil organic carbon management having the greatest potential at USD20 tCO 2 -eq –1 and restoration of organic soils at USD100 tCO 2 -eq –1 . Forestry measures were less sensitive to carbon price, but varied regionally, with reduced deforestation, forest management and afforestation having the greatest potential depending on region. Although demand-side measures related to food could in theory make a large contribution to mitigation, in reality the contribution has been very small. Overall, the dependency of mitigation within AFOLU on a complex range of factors, from population growth, economic and technological developments, to the sustainability of mitigation measures and impacts of climate change, was suggested to make realisation highly challenging ( [[#IPCC--2019|IPCC 2019]] ).

Land can only be part of the solution alongside rapid emission reduction in other sectors ( [[#IPCC--2019|IPCC 2019]] ). It was recognised that land supports many ecosystem services on which human existence, well-being and livelihoods ultimately depend. Yet over-exploitation of land resources was reported as driving considerable and unprecedented rate of biodiversity loss, and wider environmental degradation ( [[#IPBES--2019b|IPBES 2019b]] ; [[#IPCC--2019|IPCC 2019]] ). Urgent action to reverse this trend was deemed crucial in helping to accommodate the increasing demands on land and enhance climate change adaptation capacity. There was ''high confidence'' that global warming was already causing an increase in the frequency and intensity of extreme weather and climate events, impacting ecosystems, food security, disturbances and production processes, with existing (and new) carbon stocks in soils and biomass at serious risk. The impact of land cover on regional climate (through biophysical effects) was also highlighted, although there was no confidence regarding impacts on global climate.

Since the IPCC Fifth Assessment Report (AR5), the share of AFOLU to anthropogenic GHG emissions had remained largely unchanged at 13–21% of total GHG emissions ( ''medium confidence'' ), though uncertainty in estimates of both sources and sinks of CO 2 , exacerbated by difficulties in separating natural and anthropogenic fluxes, was emphasised. Models indicated land (including the natural sink) to have ''very likely'' provided a net removal of CO 2 between 2007 and 2016. As in AR5, land cover change, notably deforestation, was identified as a major driver of anthropogenic CO 2 emissions while agriculture was a major driver of the increasing anthropogenic CH 4 and N 2 O emissions.

In terms of mitigation, without reductions in overall anthropogenic emissions, increased reliance on large-scale land-based mitigation was predicted, which would add to the many already competing demands on land. However, some mitigation measures were suggested to not compete with other land uses, while also having multiple co-benefits, including adaptation capacity and potential synergies with some Sustainable Development Goals (SDGs). As in AR5, there was large uncertainty surrounding mitigation within AFOLU, in part because current carbon stocks and fluxes are unclear and subject to temporal variability. Additionally, the non-additive nature of individual measures that are often inter-linked and the highly context specific applicability of measures, causes further uncertainty. Many AFOLU measures were considered well-established and some achievable at low to moderate cost, yet contrasting economic drivers, insufficient policy, lack of incentivisation and institutional support to stimulate implementation among the many stakeholders involved, in regionally diverse contexts, was recognised as hampering realisation of potential.

None the less, the importance of mitigation within AFOLU was highlighted in all IPCC reports, with modelled scenarios demonstrating the considerable potential role and land-based mitigation forming an important component of pledged mitigation in Nationally Determined Contributions (NDCs) under the Paris Agreement. The sector was identified as the only one in which large-scale carbon dioxide removal (CDR) may currently and at short term be possible (e.g., through afforestation/reforestation or soil organic carbon management). This CDR component was deemed crucial to limit climate change and its impacts, which would otherwise lead to enhanced release of carbon from land. However, the SRCCL emphasised that mitigation cannot be pursued in isolation. The need for integrated response options, that mitigate and adapt to climate change, but also deal with land degradation and desertification, while enhancing food and fibre security, biodiversity and contributing to other SDGs has been made clear ( [[#IPCC--2019|IPCC 2019]] ; IPBES 2019a; [[#IPBES-IPCC--2021|IPBES-IPCC 2021]] ).

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=== 7.1.2 Boundaries, Scope and Changing Context of the Current Report ===

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This chapter assesses GHG fluxes between land and the atmosphere due to AFOLU, the associated drivers behind these fluxes, mitigation response options and related policy, at time scales of 2030 and 2050. Land and its management has important links with other sectors and therefore associated chapters within this report, notably concerning the provision of food, feed, fuel or fibre for human consumption and societal well-being (Chapter 5), for bioenergy (Chapter 6), the built environment (Chapter 9), transport (Chapter 10) and industry (Chapter 11). Mitigation within these sectors may in part, be dependent on contributions from land and the AFOLU sector, with interactions between all sectors discussed in Chapter 12. This chapter also has important links with IPCC AR6 WGII regarding climate change impacts and adaptation. Linkages are illustrated in Figure 7.1.

As highlighted in both AR5 and the SRCCL, there is a complex interplay between land management and GHG fluxes as illustrated in Figure 7.2, with considerable variation in management regionally, as a result of geophysical, climatic, ecological, economic, technological, institutional and socio-cultural diversity. The capacity for land-based mitigation varies accordingly. The principal focus of this chapter is therefore, on evaluating regional land-based mitigation potential, identifying applicable AFOLU mitigation measures, estimating associated costs and exploring policy options that could enable implementation.

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[[File:7224304bad0e336e9e430200042fb545 IPCC_AR6_WGIII_Figure_7_2.png]]

'''Figure 7.2 | Summarised representation of interactions between land management, its products in terms of food and fibre, and land–atmospheric GHG fluxes.''' For legibility reasons only a few of the processes and management measures are depicted.

Mitigation measures are broadly categorised as those relating to (i) forests and other ecosystems (ii) agriculture (iii) biomass production for products and bioenergy and (iv) demand-side levers. Assessment is made in the context that land-mitigation is expected to contribute roughly 25% of the 2030 mitigation pledged in Nationally Determined Contributions (NDCs) under the Paris Agreement ( [[#Grassi--2017|Grassi et al. 2017]] ), yet very few countries have provided details on how this will be achieved. In light of AR5 and the SRCCL findings, that indicate large land-based mitigation potential, considerable challenges to its realisation, but also a clear nexus at which humankind finds itself, whereby current land management, driven by population growth and consumption patterns, is undermining the very capacity of land, a finite resource, to support wider critical functions and services on which humankind depends. Mitigation within AFOLU is occasionally and wrongly perceived as an opportunity for in-action within other sectors. AFOLU simply cannot compensate for mitigation shortfalls in other sectors. As the outcomes of many critical challenges ( [[#UNEP--2019|UNEP 2019]] ), including biodiversity loss (IPBES 2019a) and soil degradation ( [[#FAO%20and%20ITPS--2015|FAO and ITPS 2015]] ), are inextricably linked with how we manage land, the evaluation and assessment of AFOLU is crucial. This chapter aims to address three core topics:

1. What is the latest estimated (economic) mitigation potential of AFOLU measures according to both sectoral studies and integrated assessment models, and how much of this may be realistic within each global region?

2. How do we realise the mitigation potential, while minimising trade-offs and risks and maximising co-benefits that can enhance food and fibre security, conserve biodiversity and address other land challenges?

3. How effective have policies been so far and what additional policies or incentives might enable realisation of mitigation potential and at what costs?

This chapter first outlines the latest trends in AFOLU fluxes and the methodology supporting their estimation ( [[#7.2|Section 7.2]] ). Direct and indirect drivers behind emission trends are discussed in [[#7.3|Section 7.3]] . Mitigation measures, their costs, co-benefits, trade-offs, estimated regional potential and contribution within integrated global mitigation scenarios, is presented in Sections 7.4 and 7.5 respectively. Assessment of associated policy responses and links with SDGs are explored in [[#7.6|Section 7.6]] . The chapter concludes with gaps in knowledge ( [[#7.7|Section 7.7]] ) and frequently asked questions.

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