Editing IPCC:AR6/WGII/Chapter-10 (section)

===== 10.4.5.2.4 Farming systems and crop areas =====

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There is new evidence since AR5 that farming systems and crop areas will change in many parts of Asia in response to climate change. In South Asia, a study in Nepal showed that farmers are inclined to change practices in cropland use to reduce climate-change risk ( [[#Chalise--2016|Chalise and Naranpanawa, 2016]] ). In India, climate change is also predicted to lead to boundary changes in areas suitable for growing certain crops (Srinivasa [[#Rao--2016|Rao et al., 2016]] ). A study in Bangladesh revealed a shift in crop choices among farmers, implying changes in the future rice-cropping pattern. Specifically, a temperature increase will compel farmers to choose irrigation-based Boro, Aus and other crops in favour of the rain-fed Aman rice crop ( [[#Moniruzzaman--2015|Moniruzzaman, 2015]] ).

In the coastal area of Odisha in India, adverse impact on the agriculture sector is anticipated considering the increasing temperature trends over the past 30 years for all the seasons ( [[#Mishra--2014|Mishra and Sahu, 2014]] ). In a national study that groups Bangladesh into 16 sub-regions with similar farming areas, simulations of a 62 cm rise in mean sea level project damages to production because of area loss in excess of 31% in sub-region 15 and nearly 40% in sub-region 16 ( [[#Ruane--2013|Ruane et al., 2013]] ). Also in Bangladesh, a study on predicting the design of water requirements for winter paddy rice under climate change conditions shows that agricultural water resource management will help minimise drought risk and implement future agricultural water resource policies (Islam et al., 2018) that may have important implications for crop areas and production.

In East Asia, the observed changes in agricultural flooding in different parts of China could influence farming systems and crop areas ( [[#Zhang--2016b|Zhang et al., 2016b]] ) as extreme events intensify in the context of changing climate. Agricultural management practice in China may also change to optimise soil organic carbon sequestration ( [[#Zhang--2016a|Zhang et al., 2016a]] ). A study on projected irrigation requirements under climate change using a soil-moisture model for 29 upland crops in the Republic of Korea showed that water scarcity is a major limiting factor for sustainable agricultural production ( [[#Hong--2016|Hong et al., 2016]] ). In terms of drought, despite increasing future precipitation in most scenarios, crop-specific agricultural drought is expected to be a significant risk due to rainfall variability ( [[#Lim--2019a|Lim et al., 2019a]] ). On the other hand, a projected rise in water availability in the Korean Peninsula using multiple regional climate models and evapotranspiration methods indicates that it will ''likely'' increase agricultural productivity for both rice and corn, but would decrease significantly in rain-fed conditions ( [[#Lim--2017b|Lim et al., 2017b]] ). Thus, irrigation and soil-water management will be a major factor in determining future farming systems and crop areas in the country.

Global studies on climate-change-induced hotspots of heat stress on agricultural crops show that large suitable cropping areas in Central and Eastern Asia, and the northern part of the Indian subcontinent, are under heat stress risk under the A1B emissions scenario ( [[#Teixeira--2013|Teixeira et al., 2013]] ) and hence may reduce cropping areas in these regions. In Japan, the projected decline in rice yield in some areas suggests that the current rice-producing regions would be divided into suitable and unsuitable areas as temperatures increases ( [[#Ishigooka--2017|Ishigooka et al., 2017]] ), with important implications regarding the possible shift in cropping area. Similarly, it has been shown that there will be change in the geographic distribution of the occurrence of poor skin colour of table-grape berries ( [[#Sugiura--2019|Sugiura et al., 2019]] ) and suitable areas for cultivation of subtropical citrus ( [[#Sugiura--2014|Sugiura et al., 2014]] ) in Japan by the middle of the 21st century.

There is emerging evidence from modelling and field experimentation that designing future farming systems and crop areas that will promote sustainable development in Asia in the context of climate change would have to incorporate not only productivity and price considerations but also how to moderate temperature increase, enhance water conservation and optimise GHG mitigation potential ( [[#Sapkota--2015|Sapkota et al., 2015]] ; [[#Zhang--2016a|Zhang et al., 2016a]] ; [[#Ko--2017|Ko et al., 2017]] ; [[#Lim--2017b|Lim et al., 2017b]] ). The effects of agricultural landscape change on ecosystem services also need to be understood and taken into account in designing farming systems and allocating farm areas ( [[#Lee--2015b|Lee et al., 2015b]] ; [[#Zanzanaini--2017|Zanzanaini et al., 2017]] ).

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