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

=== 4.7.2 Impacts of climate-related land degradation on food security ===

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How and where we grow food, compared to where and when we need to consume it, is at the crux of issues surrounding land degradation, climate change and food security, especially because more than 75% of the global land surface (excluding Antarctica) faces rain-fed crop production constraints (Fischer et al. 2009 <sup>[[#fn:r867|867]]</sup> ), see also Chapter 5. Taken separately, knowledge on land degradation processes and human-induced climate change has attained a great level of maturity. However, their combined effects on food security, notably food supply, remain underappreciated (Webb et al. 2017b <sup>[[#fn:r868|868]]</sup> ), and quantitative information is lacking. Just a few studies have shown how the interactive effects of the aforementioned challenging, interrelated phenomena can impact on crop productivity and hence food security and quality (Karami et al. 2009 <sup>[[#fn:r869|869]]</sup> ; Allen et al. 2001 <sup>[[#fn:r870|870]]</sup> ; Högy and Fangmeier 2008 <sup>[[#fn:r871|871]]</sup> ) ( ''low evidence'' ). Along with socio-economic drivers, climate change accelerates land degradation due to its influence on land-use systems (Millennium Ecosystem Assessment 2005 <sup>[[#fn:r872|872]]</sup> ; UNCCD 2017 <sup>[[#fn:r873|873]]</sup> ), potentially leading to a decline in agri-food system productivity, particularly on the supply side. Increases in temperature and changes in precipitation patterns are expected to have impacts on soil quality, including nutrient availability and assimilation (St.Clair and Lynch 2010 <sup>[[#fn:r874|874]]</sup> ). Those climate-related changes are expected to have net negative impacts on agricultural productivity, particularly in tropical regions, though the magnitude of impacts depends on the models used. Anticipated supply-side issues linked to land and climate relate to biocapacity factors (including e.g., whether there is enough water to support agriculture); production factors (e.g., chemical pollution of soil and water resources or lack of soil nutrients) and distribution issues (e.g., decreased availability of and/or accessibility to the necessary diversity of quality food where and when it is needed) (Stringer et al. 2011 <sup>[[#fn:r875|875]]</sup> ). Climate-sensitive transport infrastructure is also problematic for food security (Islam et al. 2017), and can lead to increased food waste, while poor siting of roads and transport links can lead to soil erosion and forest loss (Xiao et al. 2017 <sup>[[#fn:r877|877]]</sup> ), further feeding back into climate change.

Over the past decades, crop models have been useful tools for assessing and understanding climate change impacts on crop productivity and food security (White et al. 2011 <sup>[[#fn:r878|878]]</sup> ; Rosenzweig et al. 2014 <sup>[[#fn:r879|879]]</sup> ). Yet, the interactive effects of soil parameters and climate change on crop yields and food security remain limited, with ''low evidence'' of how they play out in different economic and climate settings (e.g., Sundström et al. 2014 <sup>[[#fn:r880|880]]</sup> ). Similarly, there have been few meta-analyses focusing on the adaptive capacity of land-use practices such as conservation agriculture in light of climate stress (see e.g., Steward et al. 2018 <sup>[[#fn:r881|881]]</sup> ), as well as ''low evidence'' quantifying the role of wild foods and forests (and, by extension, forest degradation) in both the global food basket and in supporting household-scale food security (Bharucha and Pretty 2010 <sup>[[#fn:r882|882]]</sup> ; Hickey et al. 2016 <sup>[[#fn:r883|883]]</sup> ).

To be sustainable, any initiative aimed at addressing food security – encompassing supply, diversity and quality – must take into consideration the interactive effects between climate and land degradation in a context of other socio-economic stressors. Such socio-economic factors are especially important if we look at demand-side issues too, which include lack of purchasing power, large-scale speculation on global food markets, leading to exponential price rises (Tadesse et al. 2014 <sup>[[#fn:r884|884]]</sup> ), competition in appropriation of supplies and changes to per capita food consumption (Stringer et al. 2011 <sup>[[#fn:r885|885]]</sup> ) (Chapter 5). Lack of food security, combined with lack of livelihood options, is often an important manifestation of vulnerability, and can act as a key trigger for people to migrate. In this way, migration becomes an adaptation strategy.

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