Tracing ice loss from the Late Holocene to the future in eastern Nuussuaq, central western Greenland

Abstract. Greenland's peripheral glaciers and ice caps (GICs) have experienced accelerated mass loss since the 1990s. However, the extent to which projected future trends in GICs are unprecedented within the Holocene is poorly understood. This study bridges the gap between the maximum ice extent (MIE) of the Late Holocene and present and future glacier evolution until 2100 in the eastern Nuussuaq Peninsula (central western Greenland). The Instructed Glacier Model (IGM) is calibrated and validated by simulating present-day glacier area and ice thickness. The model is employed to reconstruct the 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), based on moraine boulder surface exposure dating from previous studies. Subsequently, the model is forced with CMIP6 projections for SSP2–4.5 and SSP5–8.5 scenarios (2020–2100). The Late Holocene MIE is reached when temperatures decrease by ≤1 °C relative to the baseline climate (1960–1990) using a calibrated melt rate factor. Currently, the glaciated area and ice thickness have declined by 15±5 % compared to the MIE, with the standard deviation (±) reflecting the influence of the calibrated and low-end melt rate factors. By 2100, temperatures are projected to rise by up to 6 °C (SSP5–8.5) above the baseline, exceeding Holocene Warm Period (∼10 to 6 ka) levels by a factor of 3. Ice loss is expected to accelerate rapidly, reaching -56±6 % relative to present-day levels by 2070–2080 (SSP5–8.5), with near-total glacier disappearance projected by 2090–2100. This study contextualizes present and future glacier retreat within a geologic timescale and quantifies the impacts of anthropogenic climate change on the cryosphere.