Editing IPCC:AR6/WGII/Cross-Chapter-Paper-3 (section)

=== CCP3.3.2 Projected Impacts on Human Systems ===

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Across many drylands, human-induced causes of desertification, SDS, climate change and unsustainable land use are projected to become more pronounced over the next several decades with global consequences. Future climate changes with increasing frequency, intensity and scales of droughts and heatwaves, are projected to further exacerbate the vulnerability and risk to humans from desertification ( [[#Hurlbert--2019|Hurlbert et al., 2019]] ).

SDS exert a wide range of impacts on people, within deserts and semi-deserts but also outside dryland environments because of long-range dust transport ( [[#Middleton--2017|Middleton, 2017]] ). Research on the economic impacts of SDS is lacking, while studies that have been conducted lack consistency in data collection methods and analysis ( [[#Middleton--2019|Middleton, 2019]] ). Although projections are rarely modelled, estimated economic damages of increased dust-related health impacts and mortality under RCP8.5 could total USD 47 billion/year additional to the 1986–2005 value of USD 13 billion/year in southwest USA ( [[#Allahbakhshi--2019|Allahbakhshi et al., 2019]] ).

Projected impacts of climate change on the risk of food insecurity are a particular concern for the developing world drylands (Chapter 16; [[#Mirzabaev--2019|Mirzabaev et al., 2019]] ), potentially leading to the breakdown of food production systems, including crops, livestock and fisheries, as well as disruptions in food supply chains and distribution ( [[#Myers--2017|Myers et al., 2017]] ; [[#Lewis--2018|Lewis and Mallela, 2018]] ). Developing country drylands are particularly vulnerable due to a higher share of populations with lower income, lower physical access to nutritious food, social discrimination and other environmental factors that link to climate change. For example, countries such as Somalia, Yemen and Sudan faced recent and resurging challenges from an increase in desert locusts, the effects of which, in 2020, extended from East Africa through the Arabian Peninsula and Iran as far as India and Pakistan. [[#Meynard--2020|Meynard et al. (2020)]] note that under climate change, some areas suffering from previous outbreaks may see changes in formation of swarms of ''Schistocerca gregaria'' . [[#Salih--2020|Salih et al. (2020)]] recognise that attributing the 2020 swarms as a single event to climate change remains challenging, but highlight that projected temperature and rainfall increases in deserts and strong tropical cycles can create conditions conducive to the development, aggregation, outbreak and survival of locusts. [[#Mandumbu--2017|Mandumbu et al. (2017)]] highlight how crop parasites such as ''Striga'' spp. in southern Africa may benefit from higher temperatures and rainfall activating dormant seeds, while high winds aid their dispersal. Combined with increasing risks of erosion and soil fertility losses ( ''Striga'' is able to tolerate drought and a low nitrogen environment), this can have important impacts on the yields of key dryland crops such as maize and pearl millet.

Human responses can exacerbate desertification processes under climate change conditions, even in deserts. Exploitation of mineral resources (e.g., lithium mining in Chile’s Atacama Desert) can cause human population changes as people flock to the area for work ( [[#Liu--2019|Liu et al., 2019]] ), increasing vulnerability due to, for example, soil erosion and salinisation, as well as increasing pressure on potable water for human consumption ( [[#Stringer--2021|Stringer et al., 2021]] ) and exhausting aquifers. Salinisation is projected to increase in the drylands due to climate change impacts in future ( [[#Mirzabaev--2019|Mirzabaev et al., 2019]] ). For example, in India, about 7 million hectares of arable land area is currently affected by salt ( [[#Sharma--2015|Sharma et al., 2015]] ; [[#Sharma--2015|Sharma and Singh, 2015]] ). It is projected that unsustainable use of marginal quality waters in irrigation and neglect of drainage, combined with climate change impacts, will accelerate land salinisation in India, rendering another 9 million hectares salty and less productive by 2050 ( [[#ICAR-CSSRI--2015|ICAR-CSSRI, 2015]] ). This has important cost implications given that annually, 16.84 million tonnes of farm production valued at INR 230.19 billion is already lost in India due to salinity and associated problems ( [[#Sharma--2015|Sharma and Singh, 2015]] ). The literature further shows evidence of desertification of oases and irrigated lands in parts of northern China’s drylands ( [[#Wang--2020|Wang et al., 2020]] ), the Indian subcontinent’s deserts, as well as the Mesopotamian Arabian Desert ( [[#Ezcurra--2006|Ezcurra, 2006]] ; [[#Dilshat--2015|Dilshat et al., 2015]] ).

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