Editing IPCC:AR6/SRCCL/Chapter-3 (section)

==== 3.7.1.4 Soil erosion in Central Asia under changing climate ====

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Soil erosion is widely acknowledged to be a major form of degradation of Central Asian drylands, affecting a considerable share of croplands and rangelands. However, up-to-date information on the actual extent of eroded soils at the regional or country level is not available. The estimates compiled by Pender et al. (2009), based on the Central Asian Countries Initiative for Land Management (CACILM), indicate that about 0.8 Mha of the irrigated croplands were subject to high degree of soil erosion in Uzbekistan. In Turkmenistan, soil erosion was indicated to be occurring in about 0.7 Mha of irrigated land. In Kyrgyzstan, out of 1 Mha of irrigated land in the foothill zones, 0.76 Mha were subject to soil erosion by water, leading to losses in crop yields of 20–60% in these eroded soils. About 0.65 Mha of arable land were prone to soil erosion by wind (Mavlyanova et al. 2017 <sup>[[#fn:r1519|1519]]</sup> ). Soil erosion is widespread in rainfed and irrigated areas in Kazakhstan (Saparov 2014). About 5 Mha of rainfed croplands were subject to high levels of soil erosion (Pender et al. 2009 <sup>[[#fn:r1520|1520]]</sup> ). Soil erosion by water was indicated to be a major concern in sloping areas in Tajikistan (Pender et al. 2009 <sup>[[#fn:r1521|1521]]</sup> ).

The major causes of soil erosion in Central Asia are related to human factors, primarily excessive water use in irrigated areas (Gupta et al. 2009 <sup>[[#fn:r1522|1522]]</sup> ), deep ploughing and lack of maintenance of vegetative cover in rainfed areas (Suleimenov et al. 2014 <sup>[[#fn:r1523|1523]]</sup> ), and overgrazing in rangelands (Mirzabaev et al. 2016 <sup>[[#fn:r1524|1524]]</sup> ). Lack of good maintenance of watering infrastructure for migratory livestock grazing, and fragmentation of livestock herds led to overgrazing near villages, increasing the soil erosion by wind (Alimaev et al. 2008 <sup>[[#fn:r1526|1526]]</sup> ). Overgrazing in the rangeland areas of the region (e.g., particularly in Kyzylkum) contributes to dust storms, coming primarily from the Ustyurt Plateau, desertified areas of Amudarya and Syrdarya rivers’ deltas, the dried seabed of the Aral Sea (now called Aralkum), and the Caspian Sea (Issanova and Abuduwaili 2017 <sup>[[#fn:r1527|1527]]</sup> ; Xi and Sokolik 2015). Xi and Sokolik (2015) estimated that total dust emissions in Central Asia were 255.6 Mt in 2001, representing 10–17% of the global total.

Central Asia is one of the regions highly exposed to climate change, with warming levels projected to be higher than the global mean (Hoegh-Guldberg et al. 2018 <sup>[[#fn:r1528|1528]]</sup> ), leading to more heat extremes (Reyer et al. 2017 <sup>[[#fn:r1529|1529]]</sup> ). There is no clear trend in precipitation extremes, with some potential for moderate rise in occurrence of droughts. The diminution of glaciers is projected to continue in the Pamir and Tian Shan mountain ranges, a major source of surface waters along with seasonal snowmelt. Glacier melting will increase the hazards from moraine-dammed glacial lakes and spring floods (Reyer et al. 2017 <sup>[[#fn:r1530|1530]]</sup> ). Increased intensity of spring floods creates favourable conditions for higher soil erosion by water, especially in the sloping areas in Kyrgyzstan and Tajikistan. The continuation of some of the current unsustainable cropland and rangeland management practices may lead to elevated rates of soil erosion, particularly in those parts of the region where climate change projections point to increases in floods (Kyrgyzstan, Tajikistan) or increases in droughts (Turkmenistan, Uzbekistan) (Hijioka et al. 2014 <sup>[[#fn:r1531|1531]]</sup> ). Increasing water use to compensate for higher evapotranspiration due to rising temperatures and heat waves could increase soil erosion by water in the irrigated zones, especially in sloping areas and crop fields with uneven land levelling (Bekchanov et al. 2010 <sup>[[#fn:r1532|1532]]</sup> ). The desiccation of the Aral Sea resulted in a hotter and drier regional microclimate, adding to the growing wind erosion in adjacent deltaic areas and deserts (Kust 1999 <sup>[[#fn:r1533|1533]]</sup> ).

There are numerous sustainable land and water management practices available in the region for reducing soil erosion (Abdullaev et al. 2007 <sup>[[#fn:r1534|1534]]</sup> ; Gupta et al. 2009 <sup>[[#fn:r1535|1535]]</sup> ; Kust et al. 2014 <sup>[[#fn:r1536|1536]]</sup> ; Nurbekov et al. 2016 <sup>[[#fn:r1537|1537]]</sup> ). These include: improved land levelling and more efficient irrigation methods such as drip, sprinkler and alternate furrow irrigation (Gupta et al. 2009 <sup>[[#fn:r1538|1538]]</sup> ); conservation agriculture practices, including no-till methods and maintenance of crop residues as mulch in the rainfed and irrigated areas (Kienzler et al. 2012 <sup>[[#fn:r1539|1539]]</sup> ; Pulatov et al. 2012 <sup>[[#fn:r1540|1540]]</sup> ); rotational grazing; institutional arrangements for pooling livestock for long-distance mobile grazing; reconstruction of watering infrastructure along the livestock migratory routes (Han et al. 2016; Mirzabaev et al. 2016 <sup>[[#fn:r1541|1541]]</sup> ); afforesting degraded marginal lands (Djanibekov and Khamzina 2016 <sup>[[#fn:r1543|1543]]</sup> ; Khamzina et al. 2009 <sup>[[#fn:r1545|1545]]</sup> ; Khamzina et al. 2016 <sup>[[#fn:r1546|1546]]</sup> ); integrated water resource management (Dukhovny et al. 2013 <sup>[[#fn:r1547|1547]]</sup> ; Kazbekov et al. 2009 <sup>[[#fn:r1548|1548]]</sup> ); and planting salt – and drought-tolerant halophytic plants as windbreaks in sandy rangelands (Akinshina et al. 2016 <sup>[[#fn:r1549|1549]]</sup> ; Qadir et al. 2009 <sup>[[#fn:r1550|1550]]</sup> ; Toderich et al. 2009 <sup>[[#fn:r1551|1551]]</sup> ; Toderich et al. 2008 <sup>[[#fn:r1552|1552]]</sup> ), and potentially the dried seabed of the former Aral Sea (Breckle 2013 <sup>[[#fn:r1553|1553]]</sup> ). The adoption of enabling policies, such as those discussed in Section 3.6.3, can facilitate the adoption of these sustainable land and water management practices in Central Asia ( ''high confidence'' ) (Aw-Hassan et al. 2016 <sup>[[#fn:r1554|1554]]</sup> ; Bekchanov et al. 2016 <sup>[[#fn:r1555|1555]]</sup> ; Bobojonov et al. 2013 <sup>[[#fn:r1556|1556]]</sup> ; Djanibekov et al. 2016 <sup>[[#fn:r1557|1557]]</sup> ; Hamidov et al. 2016 <sup>[[#fn:r1559|1559]]</sup> ; Mirzabaev et al. 2016 <sup>[[#fn:r1560|1560]]</sup> ).

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