An observational constraint of global soil moisture droughts

Soil moisture drought is one of the leading hazards causing global crop yield loss. Projecting future changes in soil moisture droughts is therefore critical for informing water management and ensuring food security, but show large uncertainties not only in its frequency but also in the duration and intensity. Here, we found a strong relation between future changes in soil moisture droughts (2070-2100 relative to 1980-2014) and historical global warming rate (1980-2014) emerging from an ensemble of Earth System Models (ESMs) under the business-as-usual scenario. Combining such emergent relation with observed warming rate leads to a shift of Probability density function (PDF) of future soil moisture droughts. Compared to the raw models, the observational constraint reduces the uncertainty of future soil moisture drought by 10-18%. What’s more, a much lower estimate of future drought frequency, duration and intensity is obtained, suggesting that previous studies using the raw models may have overestimated soil moisture droughts.