The relative warmth of mid-to-late Pleistocene interglacials on Greenland has remained unknown, leading to debates about the regional climate forcing that caused past retreat of the Greenland Ice Sheet (GrIS). We analyze the hydrogen isotopic composition of terrestrial biomarkers in Labrador Sea sediments through interglacials of the past 600,000 y to infer millennial-scale summer warmth on southern Greenland. Here, we reconstruct exceptionally warm summers in Marine Isotope Stage (MIS) 5e, concurrent with strong Northern Hemisphere summer insolation. In contrast, “superinterglacial” MIS11 demonstrated only moderate warmth, sustained throughout a prolonged interval of elevated atmospheric carbon dioxide. Strong inferred GrIS retreat during MIS11 relative to MIS5e suggests an indirect relationship between maximum summer temperature and cumulative interglacial mass loss, indicating strong GrIS sensitivity to duration of regional warmth and elevated atmospheric carbon dioxide.

格陵兰岛中晚期更新世间冰期的相对温暖仍然未知，导致关于导致格陵兰冰盖 (GrIS) 过去退缩的区域气候强迫的争论。我们通过过去 600,000 年的间冰期分析拉布拉多海沉积物中陆地生物标志物的氢同位素组成，以推断格陵兰南部千年尺度的夏季温暖。在这里，我们重建了海洋同位素阶段 (MIS) 5e 中异常温暖的夏季，同时伴有强烈的北半球夏季日照。相比之下，“超间冰期” MIS11 仅表现出中等温暖，在大气二氧化碳升高的长时间间隔中持续。