Heinrich Stadial aridity forced Mediterranean-wide glacier retreat in the last cold stage

Throughout the last cold stage, the North Atlantic region was punctuated by abrupt climate shifts and atmospheric processes propagated their effects to adjacent continents. During Heinrich Stadials, the ocean was chilled by icebergs calved from the great ice sheets. The impact of multiple temperature and precipitation regime changes on Late Pleistocene mountain glaciers and landscape development is poorly understood. Here we analyse 1,118 cosmogenic exposure ages-spanning the last 100,000 years-from glacial landforms on three continents across the Mediterranean. We evaluate their geomorphological context and stratify the record by depositional setting and geographical region. The database includes 300 dated moraines. We show that, despite cold temperatures, Heinrich Stadial aridity caused negative glacier mass balance and repeatedly stalled glacier growth across the Mediterranean. In contrast, relatively warm and humid climates between Heinrich Stadials favoured positive glacier mass balance, resulting in region-wide glacier growth and moraine formation. Our analysis supports climate model simulations of repeated and widespread Heinrich Stadial aridity in the Mediterranean basin during the last cold stage. Heinrich Stadials also saw enhanced supply of coarse debris from valley sides. The cumulative geomorphological impact of these climate shifts saw the largest moraines form at the culmination of the glacial cycle.