Land use and land cover change intensified soil moisture drought: evidence from CMIP6-LUMIP

Soil moisture drought (SMD) critically constrains terrestrial ecosystems and agricultural productivity, yet the long-term contribution of historical land use and land cover change (LULCC) to global drought trends remains insufficiently quantified. We quantify the impacts of historical LULCC on SMD characteristics (event number, duration, severity, intensity) over 1901–2014 using seven offline land surface simulations from the CMIP6 Land Use Model Intercomparison Project (LUMIP). LULCC intensifies SMD over more than half of the global land area, with the strongest increases in mid-latitude regions, particularly in central North America. The drought-affected area expanded throughout the twentieth century, with drought events becoming increasingly prolonged and severe. Diagnostic analyses of SMD during the boreal growing season, based on CESM2 experiments, indicate that the transition from natural vegetation to cropland and pasture slightly reduces surface net radiation while enhancing latent heat flux at the expense of sensible heat flux. This biophysical shift depletes soil water storage, thereby increasing SMD occurrence and intensity. Our findings demonstrate that historical LULCC is a critical amplifier of SMD, underscoring the need to account for land-use dynamics in drought attribution, future risk assessment and adaptation planning.