Editing IPCC:AR6/WGII/Chapter-13 (section)

==== 13.10.2.2 KR2: Risk of Losses in Crop Production, Due to Compound Heat and Dry Conditions, and Extreme Weather ====

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Key risk 2 encompasses agriculture productivity (Figure 13.30a). It is mainly driven by the increase in the likelihood of compound heat and dry conditions and extreme weather, and their impact on crops. There is ''high confidence'' that climate change will increase the likelihood of concurrent extremely dry (Table SM13.28) and hot warm seasons with higher risks for WCE, EEU (particularly northwest Russia) and SEU leading to enhanced risk of crop failure and decrease in pasture quality ( [[#13.5.1|Section 13.5.1]] ; [[#Zscheischler--2017|Zscheischler and Seneviratne, 2017]] ; [[#Sedlmeier--2018|Sedlmeier et al., 2018]] ; [[#Seneviratne--2021|Seneviratne et al., 2021]] ). The risk is already moderately severe due to multiple crop failures in the past decade in WCE and Russia ( [[#13.5.1|Section 13.5.1]] ; [[#Hao--2018|Hao et al., 2018]] ; [[#Pfleiderer--2019|Pfleiderer et al., 2019]] ; [[#Vogel--2019|Vogel et al., 2019]] ). Under high-end scenarios, heat and drought extremes are projected to become more frequent and widespread as early as mid-century ( [[#Toreti--2019a|Toreti et al., 2019a]] ). For present to moderate adaptation and at least up to 2.5°GWL, negative consequences are mostly in SEU ( [[#Bird--2016|Bird et al., 2016]] ; [[#EEA--2019c|EEA, 2019c]] ; [[#Moretti--2019|Moretti et al., 2019]] ; [[#Feyen--2020|Feyen et al., 2020]] ). The transition from moderate to high risk is projected to happen around 2.7°C GWL when hazards and risk will become more persistent and widespread in other regions ( [[#13.1|Section 13.1]] ; [[#Deryng--2014|Deryng et al., 2014]] ; [[#Donatelli--2015|Donatelli et al., 2015]] ; [[#Webber--2018|Webber et al., 2018]] ; [[#Ceglar--2019|Ceglar et al., 2019]] ; [[#Ranasinghe--2021|Ranasinghe et al., 2021]] ; [[#Seneviratne--2021|Seneviratne et al., 2021]] ). This temperature increase will trigger shifts in agricultural zones, onset of early heat stress, losses in maize yield of up to 28% across EU-28 and regional disparity in losses and gains in wheat, which are not able to offset losses across the continent ( [[#Deryng--2014|Deryng et al., 2014]] ; [[#Szewczyk--2018|Szewczyk et al., 2018]] ; [[#Ceglar--2019|Ceglar et al., 2019]] ). There will be also broader adverse impacts such as reduction of grassland biomass production for fodder, increases in weeds and reduction in pollination ( ''medium confidence'' ) ( [[#Castellanos-Frias--2016|Castellanos-Frias et al., 2016]] ; [[#Nielsen--2017|Nielsen et al., 2017]] ; [[#Brás--2019|Brás et al., 2019]] ). Combined with socioeconomic development, increased heat and drought stress, and reduced irrigation water availability, in SEU are projected to lead to abandonment of farmland ( [[#Holman--2017|Holman et al., 2017]] ). Around 4°C GWL, the risk is very high due to persistent heat and dry conditions ( [[#Ben-Ari--2018|Ben-Ari et al., 2018]] ) and the emergence of losses also in NEU which would be much higher without the assumed CO 2 fertilisation ( [[#Deryng--2014|Deryng et al., 2014]] ; [[#Szewczyk--2018|Szewczyk et al., 2018]] ; [[#Harrison--2019|Harrison et al., 2019]] ).

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[[File:01670741c9f0a6dbc42530cf416b1e2d IPCC_AR6_WGII_Figure_13_030.png]]

'''Figure 13.30 |''' '''Burning embers and illustrative adaptation pathways for losses in crop production (Key Risk 2)'''

'''(a)''' Burning ember diagrams for losses in crop production with present or medium adaptation conditions, and with high adaptation, are shown.

'''(b)''' Illustrative adaptation pathways and key messages based on the feasibility and effectiveness assessment in Figure 13.14. Grey shading means long lead time and dotted lines signal reduced effectiveness. The circles imply transfer to another measure and the bars imply that the measure has reached a tipping point (Table SM13.28).

Farmers have historically adapted to environmental changes, and such autonomous adaptation will continue. Higher CO 2 levels have a fertilisation effect on plants that is considered to decrease crop production risks ( [[#Deryng--2014|Deryng et al., 2014]] ). Adaptation solutions to heat and drought risks include changes in sowing and harvest dates, increased irrigation, changes in crop varieties, the use of cover crops and mixed agricultural practices ( [[#13.5.2|Section 13.5.2]] ; Figures 13.14, Figure 13.30b). Under high adaptation, the use of irrigation can substantially reduce risk by both reducing canopy temperature and drought impacts ( ''high confidence'' ) ( [[#13.5.2|Section 13.5.2]] ; [[#Webber--2018|Webber et al., 2018]] ). Some reductions of maize yields in SEU are still possible, but are balanced by gains in other crops and regions ( [[#Deryng--2014|Deryng et al., 2014]] ; [[#Donatelli--2015|Donatelli et al., 2015]] ; [[#Webber--2018|Webber et al., 2018]] ; [[#Feyen--2020|Feyen et al., 2020]] ). At 3°C GWL and beyond, the adaptive capacity is reduced ( [[#Ruiz-Ramos--2018|Ruiz-Ramos et al., 2018]] ). Crop production is a major consumer of water in agriculture ( [[#Gerveni--2020|Gerveni et al., 2020]] ), yet a potentially scarcer supply of water in some regions must be distributed across many needs (KR3, [[#13.10.2.3|Section 13.10.2.3]] ), limiting availability to agriculture which is currently the main user of water in many regions of Europe ( ''high confidence'' ) ( [[#13.5.1|Section 13.5.1]] ). Where the ability to irrigate is limited by water availability, other adaptation options are insufficient to mitigate crop losses in some sub-regions, particularly at 3°C GWL and above, with an increase in risk from north to south and higher risk for late-season crops such as maize ( ''high confidence'' ). Under these conditions, land abandonment is projected ( ''low confidence'' ) ( [[#Holman--2017|Holman et al., 2017]] ).

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