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

==== 11.6.4.2 Soil Moisture Deficits ====

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There is a growing number of studies on the detection and attribution of long-term changes in soil moisture deficits. [[#Mueller--2016|Mueller and Zhang (2016)]] concluded that anthropogenic forcing contributed significantly to soil moisture drying in the warm season in the Northern Hemisphere from 1951 to 2005 and also led to an increase in the land surface area affected by soil moisture deficits, which can be reproduced by CMIP5 models only if anthropogenic forcings are involved. [[#Gu--2019b|Gu et al. (2019b)]] similarly identified a global-scale soil moisture drying tendency in land surface model data from the Global Land Data Assimilation System 2 over the time frame 1948–2005, which was attributed to anthropogenic forcing based on evaluation with CMIP5 models using optimal fingerprinting. [[#Padrón--2019|Padrón et al. (2019)]] analysed long-term reconstructed and CMIP5 simulated dry season water availability, defined as precipitation minus ET (i.e., equivalent to soil moisture and runoff availability), also related to agricultural and ecological droughts. They found an intensification of dry-season precipitation minus evapotranspiration deficits over a predominant fraction of the land area in the last three decades, which can only be explained by anthropogenic forcing and is mostly related to increases in ET. Similarly, [[#Williams--2020|Williams et al. (2020)]] concluded that human-induced climate change contributed to the strong soil moisture deficits recorded in the last two decades in Western North America through VPD increases associated with higher air temperatures and lower air humidity. There are few studies analysing the attribution of particular episodes of soil moisture deficits to anthropogenic influence. Nevertheless, the available modelling studies coincide in supporting an anthropogenic attribution associated with more extreme temperatures, exacerbating AED and increasing ET, and thus depleting soil moisture, as observed in southern Europe in 2017 ( [[#García-Herrera--2019|García-Herrera et al., 2019]] ) and in Australia in 2018 ( [[#Lewis--2020|Lewis et al., 2020]] ) and 2019 ( [[#van%20Oldenborgh--2021|van Oldenborgh et al., 2021]] ), the latter event having strong implications in the propagation of widespread megafires ( [[#Nolan--2020|Nolan et al., 2020]] ).

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