Ice core archives are well suited for reconstructing rapid past climate changes at high latitudes. Despite this, few records currently exist from coastal Greenlandic ice caps due to their remote nature, limiting our long-term understanding of past maritime and coastal climate variability across this rapidly changing Arctic region. Here, we reconstruct regionally representative glacier surface mass balance and climate variability over the last two thousand years (~169–2015 ce) using an ice core collected from the Nuussuaq Peninsula, west Greenland. We find indications of abrupt regional hydroclimate shifts, including an up to 20% decrease in average snow accumulation during the transition from the Medieval Warm Period (950–1250 ce) to Little Ice Age (1450–1850 ce), followed by a subsequent >40% accumulation increase from the early 18th to late 20th centuries ce. These coastal changes are substantially larger than those previously reported from interior Greenland records. Moreover, we show that the strong relationship observed today between Arctic temperature rise and coastal ice cap decay contrasts with that of the last millennium, during which periods of warming led to snowfall-driven glacial growth. Taken together with modern observations, the ice core evidence could indicate a recent reversal in the response of west Greenland ice caps to climate change.

冰芯档案非常适合重建过去高纬度地区的快速气候变化。尽管如此，由于格陵兰沿海冰盖的偏远性质，目前很少有记录存在，这限制了我们对这个快速变化的北极地区过去海洋和沿海气候变化的长期了解。在这里，我们使用从格陵兰岛西部努斯瓦克半岛收集的冰芯重建了过去两千年（约 169-2015 年）具有区域代表性的冰川表面质量平衡和气候变化。我们发现了区域水文气候突然变化的迹象，包括从中世纪暖期（950-1250 ce）到小冰河时代（1450-1850 ce ）的过渡期间平均积雪减少了 20%)，随后从 18 世纪初期到 20 世纪末期积累量增加了 >40 %。这些沿海变化比以前从格陵兰内部记录报告的要大得多。此外，我们表明，今天观察到的北极温度上升和沿海冰盖衰减之间的密切关系与上个千年形成鲜明对比，在此期间，变暖导致降雪驱动的冰川增长。结合现代观测，冰芯证据可能表明格陵兰岛西部冰盖对气候变化的反应最近发生了逆转。