近日，奥地利因斯布鲁克大学Gina E. Moseley团队研究了北格陵兰岩洞所记录的晚中新世北极温暖与陆地气候。该项研究成果发表在2025年10月21日出版的《自然—地球科学》杂志上。

尽管晚中新世标志着全球气候向更冷、更多变状态过渡，并且是北半球冰川作用的前奏，但人们对该时期北极陆地气候的敏感性仍知之甚少。

研究组通过分析来自格陵兰东部（卡勒利特努纳特）的石笋，建立了一个晚中新世陆地代理记录。石笋的生长周期表明，在约10至5百万年间，出现了多个永久冻土消失的时期，这表明当时的年平均气温比现在高约14°C，同时期大气二氧化碳浓度高于约310 ppm，局部海表温度异常比现在高逾2°C。此等导致永久冻土消失的适度阈值，凸显了北格陵兰地区对气候的敏感性。

约6.3和5.6百万年前硅质碎屑来源的微量元素峰值，被解释为北格陵兰地区晚中新世存在短暂冰川的陆地证据。石笋生长期间记录的气候变化主要受地轴倾角驱动，不过在晚中新世最早期，可能存在与南极地区在地轴倾角尺度上的反相位关系。在约5.6百万年后的短暂冰期-间冰期旋回阶段，区域海冰范围达到最大。该研究结果揭示了北极气候系统和永久冻土对适度二氧化碳浓度水平的敏感性，并为了解该区域对轨道驱动的响应提供了见解。

附：英文原文

Title: Late Miocene Arctic warmth and terrestrial climate recorded by North Greenland speleothems

Author: Moseley, Gina E., Koltai, Gabriella, Baker, Jonathan L., Wang, Jian, Stoll, Heather, Donner, Anika, Friedrich, Lena, Sptl, Christoph, Smith, M. Paul, Scholz, Denis, Cheng, Hai, Hartland, Adam, Hejny, Clivia, Edwards, R. Lawrence

Issue&Volume: 2025-10-21

Abstract: The sensitivity of terrestrial Arctic climate during the Late Miocene remains poorly understood, despite this interval marking the transition towards a cooler, more variable global climate and the prelude to Northern Hemisphere glaciation. Here we present a Late Miocene terrestrial proxy record, developed through the analysis of speleothems, from eastern North Greenland (Kalaallit Nunaat). Growth periods indicate multiple episodes of permafrost absence between ~10 and 5Ma, suggesting mean annual air temperatures ~14°C higher than present coinciding with atmospheric CO2 concentrations above ~310ppm and local sea surface temperature anomalies >2°C higher than present. Such moderate thresholds for permafrost absence highlight the climate sensitivity of North Greenland. Spikes in siliciclastic-derived trace elements ~6.3 and ~5.6Ma are interpreted as terrestrial indicators for Late Miocene ephemeral glaciers in North Greenland. Climate variability recorded during speleothem growth periods was predominantly forced by obliquity, although, in the earliest Late Miocene, obliquity-scale anti-phasing with Antarctica may have occurred. Regional sea-ice extent was at its greatest following ~5.6Ma during phases of transient glacial–interglacial cycles. Our findings highlight the sensitivity of the Arctic climate system and permafrost to modest CO2 levels and provide insights into regional responses to orbital forcing.

DOI: 10.1038/s41561-025-01822-0

Source: https://www.nature.com/articles/s41561-025-01822-0