Abstract Knowledge about the future response of the Greenland Ice Sheet to global climate change, including ice sheet contributions to sea level rise, is important for understanding the impact of climate change on society. Such studies rely in ice sheet model predictions and improved chronological constraints of past ice sheet extents and paleoclimatic trends. Many regions in Greenland are well studied, but northwest Greenland and especially Melville Bay, being one of the most important regions in terms of dynamical ice mass loss, lack a firm chronology of Holocene ice marginal fluctuations. In this study, we present the first comprehensive chronology for Melville Bay spanning 73.1–75.7°N based on 36 new 10Be exposure ages of boulders and 39 new radiocarbon ages of marine molluscs in Little Ice Age moraines. From weighted mean 10Be exposure ages, excluding 6 outliers, we find that the outer coast in Melville Bay was deglaciated ∼11.6 ± 0.3 ka (n = 15) and the ice margin reached its present-day position 40 km farther inland ∼11.5 ± 0.3 ka (n = 15). Our results suggest an interval of rapid ice-marginal retreat (i.e. collapse) of the northwest GrIS in Melville Bay, most likely triggered by rapidly rising atmospheric temperatures in early Holocene. Additionally, combining the comprehensive dataset of new radiocarbon ages with 26 radiocarbon ages from previous studies shows a restricted ice sheet extent from 9.1 ± 0.2 to 0.4 ± 0.1 cal ka BP, which coincides with increased sea surface temperatures. Our results highlight past ice sheet sensitivity towards climate changes in one of the least explored and most vulnerable regions of Greenland. Furthermore, comparing our new results to already existing ice sheet models (Huy3 and Huy3b) emphasize the proximal relevance of the Agassiz ice core temperature reconstruction for Melville Bay, which indicates the possible sensitivity of the ice sheet to a warming climate and place improved constraints on ice sheet simulations.

中文翻译：

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大气变暖引发格陵兰岛西北部海基冰的全新世早期崩塌

摘要 了解格陵兰冰盖对全球气候变化的未来响应，包括冰盖对海平面上升的贡献，对于理解气候变化对社会的影响非常重要。此类研究依赖于冰盖模型预测以及对过去冰盖范围和古气候趋势的改进时间限制。格陵兰岛的许多地区都得到了很好的研究，但格陵兰岛西北部，尤其是梅尔维尔湾，是动态冰量损失最重要的地区之一，缺乏全新世冰边缘波动的确切年表。在这项研究中，我们根据 36 个新的 10Be 巨石暴露年龄和 39 个新的小冰河期冰碛海洋软体动物放射性碳年龄，展示了跨越 73.1-75.7°N 的梅尔维尔湾的第一个综合年表。从加权平均 10Be 暴露年龄，排除 6 个异常值，我们发现梅尔维尔湾的外海岸冰川消融了 ∼11.6 ± 0.3 ka (n = 15)，冰缘到达内陆 40 公里处的今天位置∼11.5 ± 0.3 ka (n = 15)。我们的研究结果表明，梅尔维尔湾西北部的 GrIS 有一段快速的冰缘退缩（即坍塌）间隔，这很可能是由全新世早期大气温度的快速上升引发的。此外，将新放射性碳年龄的综合数据集与先前研究中的 26 个放射性碳年龄相结合，表明冰盖范围从 9.1 ± 0.2 到 0.4 ± 0.1 cal ka BP，这与海面温度升高相吻合。我们的结果突出了格陵兰岛探索最少和最脆弱的地区之一过去冰盖对气候变化的敏感性。此外，