Changes in the Greenland ice sheet (GIS) affect global sea level. Greenland stable water isotope (δ¹⁸O) records from ice cores offer information on past changes in the surface of the GIS. Here, we use the isotope-enabled Hadley Centre Coupled Model version 3 (HadCM3) climate model to simulate a set of last interglacial (LIG) idealised GIS surface elevation change scenarios focusing on GIS ice core sites. We investigate how δ¹⁸O depends on the magnitude and sign of GIS elevation change and evaluate how the response is altered by sea ice changes. We find that modifying GIS elevation induces changes in Northern Hemisphere atmospheric circulation, sea ice and precipitation patterns. These climate feedbacks lead to ice-core-averaged isotopic lapse rates of 0.49 ‰ (100 m)⁻¹ for the lowered GIS states and 0.29 ‰ (100 m)⁻¹ for the enlarged GIS states. This is lower than the spatially derived Greenland lapse rates of 0.62–0.72 ‰ (100 m)⁻¹. These results thus suggest non-linearities in the isotope–elevation relationship and have consequences for the interpretation of past elevation and climate changes across Greenland. In particular, our results suggest that winter sea ice changes may significantly influence isotope–elevation gradients: winter sea ice effect can decrease (increase) modelled core-averaged isotopic lapse rate values by about −19 % (and +28 %) for the lowered (enlarged) GIS states, respectively. The largest influence of sea ice on δ¹⁸O changes is found in coastal regions like the Camp Century site.

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海冰的反馈影响格陵兰冰盖海拔变化的同位素特征：最后的冰间期HadCM3模拟

格陵兰冰原（GIS）的变化会影响全球海平面。格陵兰稳定同位素水（δ ¹⁸ Ø从冰芯）记录提供有关在GIS的表面改变过去信息。在这里，我们使用支持同位素的哈德利中心耦合模型版本3（HadCM3）气候模型来模拟一组最后的冰间期（LIG）理想化的GIS表面海拔高度变化场景，重点是GIS冰芯站点。我们研究如何δ ¹⁸ Ø取决于GIS高程变化的幅度和符号，并评估海冰变化如何改变响应。我们发现，修改GIS海拔会引起北半球大气环流，海冰和降水模式的变化。这些气候反馈导致较低的GIS状态的冰芯平均同位素流失率为0.49‰（100 m）^-1，对于较大的GIS状态的冰芯平均同位素流失率为0.29‰（100 m）^-1。这低于0.62–0.72‰（100 m）^-1的空间推导格陵兰流失率。因此，这些结果表明同位素与海拔的关系呈非线性，并对格陵兰过去的海拔和气候变化的解释产生影响。特别是，我们的研究结果表明，冬季海冰的变化可能会显着影响同位素-海拔梯度：冬季海冰效应可以使模拟的岩心平均同位素消失率值降低（增加），降低的幅度约为− 19％（和+ 28％）。 （放大）GIS状态。海冰上的影响最大δ ¹⁸ Ø变化，如营世纪网站沿海地区发现。