Strong latitudinal contrasts in global wet/dry patterns since the Last Glacial Maximum and under future warming

Understanding regional wetting and drying under global warming remains challenging. Here we show, using global climate simulations and 191 records of past climate, that terrestrial moisture changes over the past 21,000 years follow a pronounced latitudinal pattern. Our reconstruction shows progressive wetting at high northern latitudes from the Last Glacial Maximum to the pre-industrial period. By contrast, many regions dominated by mid-latitude westerly winds are wetter during cold periods, whereas low-latitude monsoon regions are generally wetter during warm periods. These contrasts arise from seasonal changes in precipitation and evaporation and shifts in atmospheric circulation caused by changing ice sheets, greenhouse gas concentrations, and incoming solar radiation. A similar latitude-dependent structure appears in modern observations. Future simulations project drying across many subtropical and mid-latitude regions, but wetting at high latitudes and in monsoon regions. Continued warming is therefore likely to strengthen global differences between drying and wetting regions and expand water stress in vulnerable drylands. Global wet and dry changes since the Last Glacial Maximum reveal strong latitudinal contrasts as shown by model simulation and lake-level records; future warming will exacerbate the spread of arid zones and the global wet and dry differentiation will expand.