NOAA/WDS Paleoclimatology - Northeast Greenland 537-622 Kyr Speleothem d18O and d13C Data

The five interglacials before the Mid-Brunhes Event (MBE) [c.430 thousand years (ka) ago] are generally considered to be globally cooler than those post-MBE. Inhomogeneities exist regionally, however, which suggest that the Arctic was warmer than present during Marine Isotope Stage (MIS) 15a. Using the first speleothem record for the High Arctic, we investigate the climatic response of northeast Greenland between c.588 and c.549 ka ago. Our results indicate an enhanced warmth of at least +3.5C relative to the present, leading to permafrost thaw and increased precipitation. We find that d18O of precipitation was at least 3 per mil higher than today and recognize two local cooling events (c.571 and c.594 ka ago) thought to be caused by freshwater forcing. Our results are important for improving understanding of the regional climatic response leading up to the MBE and specifically provide insights into the climatic response of a warmer Arctic.

中布容事件（Mid-Brunhes Event, MBE，约43万年前）之前的五次间冰期，普遍被认为在全球范围内均较中布容事件之后的间冰期更为寒冷。然而区域间存在气候不均一性，研究显示海洋同位素阶段（Marine Isotope Stage, MIS）15a时期的北极地区温度较现代更高。本研究利用首个针对高北极地区的石笋记录，对约58.8万至54.9万年前格陵兰东北部的气候响应展开探究。结果表明，该区域彼时温度较现代至少升高3.5℃，由此引发冻土消融与降水增加。研究发现，彼时降水的δ¹⁸O较现代至少高出3千分比，同时识别出两起局地降温事件（分别约为57.1万年前与59.4万年前），推测其由淡水强迫作用所致。本研究结果有助于深化对中布容事件前区域气候响应的认知，尤其为北极变暖背景下的气候响应机制提供了新的科学见解。