Editing IPCC:AR6/WGI/Chapter-11 (section)

==== 11.6.3.1 Precipitation Deficits ====

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ESMs generally show limited performance and large spread in identifying precipitation deficits and associated long-term trends in comparison with observations ( [[#Nasrollahi--2015|Nasrollahi et al., 2015]] ). Meteorological drought trends in the CMIP5 ensemble showed substantial disagreements compared with observations ( [[#Orlowsky--2013|Orlowsky and Seneviratne, 2013]] ; [[#Knutson--2018|Knutson and Zeng, 2018]] ) including a tendency to overestimate drying, in particular in mid- to high latitudes ( [[#Knutson--2018|Knutson and Zeng, 2018]] ). The CMIP6 models display a better performance in reproducing long-term precipitation trends or seasonal dynamics in some studies in Southern South America ( [[#Rivera--2020|Rivera and Arnould, 2020]] ), East Asia ( [[#Xin--2020|Xin et al., 2020]] ), southern Asia ( [[#Gusain--2020|Gusain et al., 2020]] ), and south-western Europe ( [[#Peña-Angulo--2020b|Peña-Angulo et al., 2020b]] ), but there is still too ''limited evidence'' to allow for an assessment of possible differences in performance between CMIP5 and CMIP6. Furthermore, ESMs are generally found to underestimate the severity of precipitation deficits and the dry day frequencies in comparison to observations ( [[#Fantini--2018|Fantini et al., 2018]] ; [[#Ukkola--2018|Ukkola et al., 2018]] ). This is probably related to shortcomings in the simulation of persistent weather events in the mid-latitudes ( [[IPCC:Wg1:Chapter:Chapter-10#10.3.3.3|Section 10.3.3.3]] ). ESMs also show a tendency to underestimate precipitation-based drought persistence at monthly to decadal time scales ( [[#Ault--2014|Ault et al., 2014]] ; [[#Moon--2018|Moon et al., 2018]] ). The overall inter-model spread in the projected frequency of precipitation deficits is also substantial ( [[#Touma--2015|Touma et al., 2015]] ; [[#Zhao--2016|Zhao et al., 2016]] ; [[#Engström--2018|Engström and Keellings, 2018]] ). Moreover, there are spatial differences in the spread, which is higher in the regions where enhanced drought conditions are projected and under high-emissions scenarios ( [[#Orlowsky--2013|Orlowsky and Seneviratne, 2013]] ). Nonetheless, some event attribution studies have concluded that droughts at regional scales can be adequately simulated by some climate models ( [[#Schaller--2016|Schaller et al., 2016]] ; [[#Otto--2018c|Otto et al., 2018c]] ).

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