Occurrence of Heinrich stadials in the West Mediterranean and West African regions and their connections to atmospheric circulation changes

During the last glacial period, Heinrich Stadials disrupted North Atlantic circulation and induced major continental climate shifts. However, their spatial variability and latitudinal intensity remain poorly constrained. Here we investigate Heinrich Stadial signals across the West Mediterranean, West Africa and West-Central Africa by integrating pollen-based quantitative precipitation reconstructions, paleohydrological records and HadCM3B climate simulations. Results reveal pronounced aridity in the West Mediterranean, driven by reduced evaporation and weakened westerlies. West Africa also experienced aridity, primarily linked to intensified wind systems, including the northeast trade winds and African easterly jet. Notably, Heinrich Stadial 3 is absent in this region. By contrast, Heinrich Stadials are undetected in West-Central Africa, likely due to its transitional position between arid northern and humid southern air masses, positive evaporation-precipitation anomalies, and the influence of southeast trade winds that sustained humidity. These findings highlight strong regional contrasts in the Heinrich Stadial impacts over the last 70 kyr.