Earliest Holocene south Greenland ice sheet retreat within its late Holocene extent

Early Holocene summer warmth drove dramatic Greenland ice sheet (GIS) retreat. Subsequent insolation-driven cooling caused GIS margin readvance to late Holocene maxima, from which ice margins are now retreating. We use ¹⁰Be surface exposure ages from four locations between 69.4°N and 61.2°N to date when in the early Holocene south to west GIS margins retreated to within these late Holocene maximum extents. We find that this occurred at 11.1±0.2 ka to 10.6±0.5 ka in south Greenland, significantly earlier than previous estimates, and 6.8±0.1 ka to 7.9±0.1 ka in southwest to west Greenland, consistent with existing ¹⁰Be ages. At least in south Greenland, these ¹⁰Be ages likely provide a minimum constraint for when on a multicentury timescale summer temperatures after the last deglaciation warmed above late Holocene temperatures in the early Holocene. Current south Greenland ice margin retreat suggests that south Greenland may have now warmed to or above earliest Holocene summer temperatures. Key Points South Greenland ice retreated within its near-present margins 11.1-10.6 ka South Greenland ice receded inboard of modern extent 3-4 ka earlier than west Current south Greenland summer climate may be similar to that of the early Holocene