Editing IPCC:AR6/SRCCL/Chapter-4 (section)

=== 4.8.5 Policy responses to land degradation ===

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The 1992 United Nations Conference on Environment and Development (UNCED), also known as the Rio de Janeiro Earth Summit, recognised land degradation as a major challenge to sustainable development, and led to the establishment of the UNCCD, which specifically addressed land degradation in the drylands. The UNCCD emphasises sustainable land use to link poverty reduction on one hand and environmental protection on the other. The two other ‘Rio Conventions’ emerging from the UNCED – the UNFCCC and the Convention on Biological Diversity (CBD) – focus on climate change and biodiversity, respectively. The land has been recognised as an aspect of common interest to the three conventions, and SLM is proposed as a unifying theme for current global efforts on combating land degradation, climate change and loss of biodiversity, as well as facilitating land-based adaptation to climate change and sustainable development.

The Global Environmental Facility (GEF) funds developing countries to undertake activities that meet the goals of the conventions and deliver global environmental benefits. Since 2002, the GEF has invested in projects that support SLM through its Land Degradation Focal Area Strategy, to address land degradation within and beyond the drylands.

Under the UNFCCC, parties have devised National Adaptation Plans (NAPs) that identify medium- and long-term adaptation needs. Parties have also developed their climate change mitigation plans, presented as NDCs. These programmes have the potential of assisting the promotion of SLM. It is understood that the root causes of land degradation and successful adaptation will not be realised until holistic solutions to land management are explored. SLM can help address root causes of low productivity, land degradation, loss of income-generating capacity, as well as contribute to the amelioration of the adverse effects of climate change.

The ‘4 per 1000’ (4p1000) initiative (Soussana et al. 2019 <sup>[[#fn:r1130|1130]]</sup> ) launched by France during the UNFCCC COP21 in 2015 aims at capturing CO <sub>2</sub> from the atmosphere through changes to agricultural and forestry practices at a rate that would increase the carbon content of soils by 0.4% per year (Rumpel et al. 2018 <sup>[[#fn:r1131|1131]]</sup> ). If global soil carbon content increases at this rate in the top 30–40 cm, the annual increase in atmospheric CO <sub>2</sub> would be stopped (Dignac et al. 2017 <sup>[[#fn:r1132|1132]]</sup> ). This is an illustration of how extremely important soils are for addressing climate change. The initiative is based on eight steps: stop carbon loss (priority #1 is peat soils); promote carbon uptake; monitor, report and verify impacts; deploy technology for tracking soil carbon; test strategies for implementation and upscaling; involve communities; coordinate policies; and provide support (Rumpel et al. 2018 <sup>[[#fn:r1133|1133]]</sup> ). Questions remain, however, about the extent that the 4p1000 is achievable as a universal goal (van Groenigen et al. 2017 <sup>[[#fn:r1134|1134]]</sup> ; Poulton et al. 2018 <sup>[[#fn:r1135|1135]]</sup> ; Schlesinger and Amundson 2018 <sup>[[#fn:r1136|1136]]</sup> ).

LDN was introduced by the UNCCD at Rio +20, and adopted at UNCCD COP12 (UNCCD 2016a <sup>[[#fn:r1137|1137]]</sup> ). LDN is defined as ‘a state whereby the amount and quality of land resources necessary to support ecosystem functions and services and enhance food security remain stable or increase within specified temporal and spatial scales and ecosystems’(Cowie et al. 2018 <sup>[[#fn:r1138|1138]]</sup> ). Pursuit of LDN requires effort to avoid further net loss of the land-based natural capital relative to a reference state, or baseline. LDN encourages a dual-pronged effort involving SLM to reduce the risk of land degradation, combined with efforts in land restoration and rehabilitation, to maintain or enhance land-based natural capital, and its associated ecosystem services (Orr et al. 2017 <sup>[[#fn:r1139|1139]]</sup> ; Cowie et al. 2018 <sup>[[#fn:r1140|1140]]</sup> ). Planning for LDN involves projecting the expected cumulative impacts of land-use and land management decisions, then counterbalancing anticipated losses with measures to achieve equivalent gains, within individual land types (where land type is defined by land potential). Under the LDN framework developed by UNCCD, three primary indicators are used to assess whether LDN is achieved by 2030: land cover change; net primary productivity; and soil organic carbon (Cowie et al. 2018 <sup>[[#fn:r1141|1141]]</sup> ; Sims et al. 2019 <sup>[[#fn:r1142|1142]]</sup> ). Achieving LDN therefore requires integrated landscape management that seeks to optimise land use to meet multiple objectives (ecosystem health, food security, human well-being) (Cohen-Shacham et al. 2016 <sup>[[#fn:r1143|1143]]</sup> ). The response hierarchy of Avoid &gt; Reduce &gt; Reverse land degradation articulates the priorities in planning LDN interventions. LDN provides the impetus for widespread adoption of SLM and efforts to restore or rehabilitate land. Through its focus, LDN ultimately provides tremendous potential for mitigation of, and adaptation to, climate change by halting and reversing land degradation and transforming land from a carbon source to a sink. There are strong synergies between the concept of LDN and the NDCs of many countries, with linkages to national climate plans. LDN is also closely related to many Sustainable Development Goals (SDG) in the areas of poverty, food security, environmental protection and sustainable use of natural resources (UNCCD 2016b <sup>[[#fn:r1144|1144]]</sup> ). The GEF is supporting countries to set LDN targets and implement their LDN plans through its land degradation focal area, which encourages application of integrated landscape approaches to managing land degradation (GEF 2018 <sup>[[#fn:r1145|1145]]</sup> ).

The 2030 Agenda for Sustainable Development, adopted by the United Nations in 2015, comprises 17 SDGs. Goal 15 is of direct relevance to land degradation, with the objective to protect, restore and promote sustainable use of terrestrial ecosystems, sustainably manage forests, combat desertification and halt and reverse land degradation and halt biodiversity loss. Target 15.3 specifically addresses LDN. Other goals that are relevant for land degradation include Goal 2 (Zero hunger), Goal 3 (Good health and well-being), Goal 7 (Affordable and clean energy), Goal 11 (Sustainable cities and communities), and Goal 12 (Responsible production and consumption). Sustainable management of land resources underpins the SDGs related to hunger, climate change and environment. Further goals of a cross-cutting nature include 1 (No poverty), 6 (Clean water and sanitation) and 13 (Climate action). It remains to be seen how these interconnections are dealt with in practice.

With a focus on biodiversity, IPBES published a comprehensive assessment of land degradation in 2018 (Montanarella et al. 2018 <sup>[[#fn:r1146|1146]]</sup> ). The IPBES report, together with this report focusing on climate change, may contribute to creating a synergy between the two main global challenges for addressing land degradation in order to help achieve the targets of SDG 15 (protect, restore and promote sustainable use of terrestrial ecosystems, sustainably manage forests, combat desertification, and halt and reverse land degradation and halt biodiversity loss).

Market-based mechanisms like the Clean Development Mechanism (CDM) under the UNFCCC and the voluntary carbon market provide incentives to enhance carbon sinks on the land through afforestation and reforestation. Implications for local land use and food security have been raised as a concern and need to be assessed (Edstedt and Carton 2018 <sup>[[#fn:r1147|1147]]</sup> ; Olsson et al. 2014b <sup>[[#fn:r1148|1148]]</sup> ). Many projects aimed at reducing emissions from deforestation and forest degradations (not to be confused with the national REDD+ programmes in accordance with the UNFCCC Warsaw Framework) are being planned and implemented to primarily target countries with high forest cover and high deforestation rates. Some parameters of incentivising emissions reduction, quality of forest governance, conservation priorities, local rights and tenure frameworks, and sub-national project potential are being looked into, with often very mixed results (Newton et al. 2016 <sup>[[#fn:r1149|1149]]</sup> ; Gebara and Agrawal 2017 <sup>[[#fn:r1150|1150]]</sup> ).

Besides international public initiatives, some actors in the private sector are increasingly aware of the negative environmental impacts of some global value chains producing food, fibre, and energy products (Lambin et al. 2018 <sup>[[#fn:r1151|1151]]</sup> ; van der Ven and Cashore 2018 <sup>[[#fn:r1152|1152]]</sup> ; van der Ven et al. 2018 <sup>[[#fn:r1153|1153]]</sup> ; Lyons-White and Knight 2018 <sup>[[#fn:r1154|1154]]</sup> ). While improvements are underway in many supply chains, measures implemented so far are often insufficient to be effective in reducing or stopping deforestation and forest degradation (Lambin et al. 2018 <sup>[[#fn:r1155|1155]]</sup> ). The GEF is investing in actions to reduce deforestation in commodity supply chains through its Food Systems, Land Use, and Restoration Impact Program (GEF 2018 <sup>[[#fn:r1156|1156]]</sup> ).

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==== 4.8.5.1 Limits to adaptation ====

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SLM can be deployed as a powerful adaptation strategy in most instances of climate change impacts on natural and social systems, yet there are limits to adaptation (Klein et al. 2014 <sup>[[#fn:r1157|1157]]</sup> ; Dow, Berhout and Preston 2013 <sup>[[#fn:r1158|1158]]</sup> ). Such limits are dynamic and interact with social and institutional conditions (Barnett et al. 2015 <sup>[[#fn:r1159|1159]]</sup> ; Filho and Nalau 2018 <sup>[[#fn:r1160|1160]]</sup> ). Exceeding adaptation limits will trigger escalating losses or require undesirable transformational change, such as forced migration. The rate of change in relation to the rate of possible adaptation is crucial (Dow et al. 2013 <sup>[[#fn:r1161|1161]]</sup> ). How limits to adaptation are defined, and how they can be measured, is contextual and contested. Limits must be assessed in relation to the ultimate goals of adaptation, which is subject to diverse and differential values (Dow et al. 2013 <sup>[[#fn:r1162|1162]]</sup> ; Adger et al. 2009 <sup>[[#fn:r1163|1163]]</sup> ). A particularly sensitive issue is whether migration is accepted as adaptation or not (Black et al. 2011 <sup>[[#fn:r1164|1164]]</sup> ; Tacoli 2009 <sup>[[#fn:r1165|1165]]</sup> ; Bardsley and Hugo 2010 <sup>[[#fn:r1166|1166]]</sup> ). If migration were understood and accepted as a form of successful adaptation, it would change the limits to adaptation by reducing, or even avoiding, future humanitarian crises caused by climate extremes (Adger et al. 2009 <sup>[[#fn:r1167|1167]]</sup> ; Upadhyay et al. 2017 <sup>[[#fn:r1168|1168]]</sup> ; Nalau et al. 2018 <sup>[[#fn:r1169|1169]]</sup> ).

In the context of land degradation, potential limits to adaptation exist if land degradation becomes so severe and irreversible that livelihoods cannot be maintained, and if migration is either not acceptable or not possible. Examples are coastal erosion where land disappears (Gharbaoui and Blocher 2016 <sup>[[#fn:r1170|1170]]</sup> ; Luetz 2018 <sup>[[#fn:r1171|1171]]</sup> ), collapsing livelihoods due to thawing of permafrost (Landauer and Juhola 2019 <sup>[[#fn:r1172|1172]]</sup> ), and extreme forms of soil erosion, (e.g., landslides (Van der Geest and Schindler 2016 <sup>[[#fn:r1173|1173]]</sup> ) and gully erosion leading to badlands (Poesen et al. 2003 <sup>[[#fn:r1174|1174]]</sup> )).

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