Projected climate change will double the Late Holocene maximum to present ice loss in Central-Western Greenland by 2070

Abstract. Greenland's peripheral glaciers and ice caps (GICs) have experienced accelerated mass loss since the 1990s. However, the extent to which present and future trends of GICs are unprecedented within the Holocene is poorly understood. This study bridges the gap between the maximum ice extent (MIE) of the Late Holocene, present and future glacier evolution until 2100 in Eastern Nuussuaq Peninsula (Central-Western Greenland), where the age of moraine boulders was determined by surface exposure dating. The glacier evolution model Instructed Glacier Model (IGM) is calibrated and validated by simulating present-day glacier area and ice thickness. The model is employed to reconstruct eastern Nuussuaq Peninsula GICs to align with the MIE of the Late Holocene, which occurred during the late Medieval Warm Period (1130 ± 40 and 925 ± 80 CE). Subsequently, the model is forced with CMIP6 projections for SSP2-4.5 and SSP5-8.5 scenarios (2020–2100). Glaciers reach the MIE of the Late Holocene when temperatures decrease between 1 °C to 1.25 °C relative to the baseline climate period (1960–1990). Currently, glaciers have retreated by 34 % compared to the MIE of the Late Holocene. By the end of the 21st century (2100), temperatures are projected rise up to 6 °C (SSP5-8.5) with respect to the baseline climate, exceeding temperatures prevailing during the Holocene Warm Period (~10 to 6 ka) by a factor of three. Using IGM with a positive degree-day model calibrated with geodetic mass balance data from 2000–2020, we project that by >2070 under SSP2-4.5 and SSP5-8.5, glacier mass loss will double (-70 %) the loss trend observed from the MIE of the Late Holocene to the present. This work helps contextualize present and future glacier retreat within a geologic time scale and quantify the impacts of anthropogenic climate change on the cryosphere.