Institute of Applied Geology, University of Natural Resources and Life Sciences (BOKU), Peter Jordan-Straße 82, 1190, Vienna, Austria.
Division of Geochemistry, Lamont-Doherty Earth Observatory of Columbia University, Palisades, NY, 10964, USA.
Sci Rep. 2022 Jun 13;12(1):9438. doi: 10.1038/s41598-022-12477-x.
Climate is currently warming due to anthropogenic impact on the Earth's atmosphere. To better understand the processes and feedbacks within the climate system that underlie this accelerating warming trend, it is useful to examine past periods of abrupt climate change that were driven by natural forcings. Glaciers provide an excellent natural laboratory for reconstructing the climate of the past as they respond sensitively to climate oscillations. Therefore, we study glacier systems and their behavior during the transition from colder to warmer climate phases, focusing on the period between 15 and 10 ka. Using a combination of geomorphological mapping and beryllium-10 surface exposure dating, we reconstruct ice extents in two glaciated valleys of the Silvretta Massif in the Austrian Alps. The mountain glacier record shows that general deglaciation after the Last Glacial Maximum (LGM) was repeatedly interrupted by glacier stabilization or readvance, perhaps during the Oldest Dryas to Bølling transition (landform age: 14.4 ± 1.0 ka) and certainly during the Younger Dryas (YD; 12.9-11.7 ka) and the Early Holocene (EH; 12-10 ka). The oldest landform age indicates a lateral ice margin that postdates the 'Gschnitz' stadial (ca. 17-16 ka) and predates the YD. It shows that local inner-alpine glaciers were more extensive until the onset of the Bølling warm phase (ca. 14.6 ka), or possibly even into the Bølling than during the subsequent YD. The second age group, ca. 80 m below the (pre-)Bølling ice margin, indicates glacier extents during the YD cold phase and captures the spatial and temporal fine structure of glacier retreat during this period. The ice surface lowered approximately 50-60 m through the YD, which is indicative of milder climate conditions at the end of the YD compared to its beginning. Finally, the third age group falls into a period of more substantial warming, the YD-EH transition, and shows discontinuous glacier retreat during the glacial to interglacial transition. The new geochronologies synthesized with pre-existing moraine records from the Silvretta Massif evidence multiple cold phases that punctuated the general post-LGM warming trend and illustrate the sensitive response of Silvretta glaciers to abrupt climate oscillations in the past.
由于人类活动对地球大气的影响，目前气候正在变暖。为了更好地理解导致这种加速变暖趋势的气候系统内的过程和反馈，研究由自然因素驱动的过去突然气候变化时期是有用的。冰川为重建过去的气候提供了极好的天然实验室，因为它们对气候振荡敏感。因此，我们研究了冰川系统及其在从较冷到较暖气候阶段转变过程中的行为，重点关注 15 至 10 千年前的时期。我们使用地貌测绘和铍-10 表面暴露测年的组合，重建了奥地利阿尔卑斯山脉西尔弗拉泰特山系两个冰川谷的冰盖范围。山地冰川记录表明，末次冰期最大值（LGM）后的普遍融冰过程多次被冰川稳定或前进所打断，也许是在最古老的干燥期到博林期转变期间（地貌年龄：14.4±1.0 千年前），肯定是在新仙女木期（YD；12.9-11.7 千年前）和早全新世（EH；12-10 千年前）期间。最古老的地貌年龄表明，侧向冰缘晚于“Gschnitz”冰期（约 17-16 千年前），早于 YD。这表明，当地的高山冰川在博林暖期（约 14.6 千年前）开始之前或甚至在博林期内，都比 YD 期间更加广泛。第二个年龄组位于（前）博林冰缘下方约 80 米处，指示了 YD 冷期的冰川范围，并捕获了该时期冰川后退的时空精细结构。冰面通过 YD 降低了约 50-60 米，表明 YD 末期的气候条件比其初期更温和。最后，第三个年龄组属于气候变暖程度较大的时期，即 YD-EH 过渡时期，并且在冰川到间冰期的过渡期间显示出不连续的冰川后退。与西尔弗拉泰特山系的现有冰碛记录综合的新地质年代学证据表明，多个冷期打断了 LGM 后普遍变暖的趋势，并说明了西尔弗拉泰特冰川对过去突然气候振荡的敏感反应。
