Larsen Darren J, Crump Sarah E, Blumm Aria
Department of Geology, Occidental College, Los Angeles, CA 90041, USA.
Institute of Arctic and Alpine Research, University of Colorado, Boulder, CO 80309, USA.
Sci Adv. 2020 Nov 18;6(47). doi: 10.1126/sciadv.abc7661. Print 2020 Nov.
Geological evidence indicates that glaciers in the western United States fluctuated in response to Holocene changes in temperature and precipitation. However, because moraine chronologies are characteristically discontinuous, Holocene glacier fluctuations and their climatic drivers remain ambiguous, and future glacier changes are uncertain. Here, we construct a continuous 10-thousand-year (ka) record of glacier activity in the Teton Range, Wyoming, using glacial and environmental indicators in alpine lake sediments. We show that Teton glaciers persisted in some form through early Holocene warmth, likely as small debris-covered glaciers or rock glaciers. Subsequent Neoglacial ice expansion began ~6.3 ka, with two prominent glacier maxima at ~2.8 and 0.1 ka that were separated by a multicentennial phase of ice retreat. Comparison with regional paleoclimate records suggests that glacier activity was dominantly controlled by winter precipitation variability superposed on long-term Holocene temperature trends, offering key insights into western U.S. glacier resilience and vulnerability to future warming.
地质证据表明,美国西部的冰川随着全新世温度和降水的变化而波动。然而,由于冰碛年代学具有典型的不连续性,全新世冰川波动及其气候驱动因素仍不明确,未来冰川变化也不确定。在此,我们利用高山湖泊沉积物中的冰川和环境指标,构建了怀俄明州提顿山脉连续1万年的冰川活动记录。我们发现,提顿冰川在全新世早期温暖阶段以某种形式持续存在,可能是小型的碎屑覆盖冰川或石冰川。随后的新冰期冰体扩张始于约6300年前,在约2800年和100年前出现了两个显著的冰川最大值,中间隔着一个持续数百年的冰退阶段。与区域古气候记录的对比表明,冰川活动主要受叠加在全新世长期温度趋势上的冬季降水变化控制,这为了解美国西部冰川的恢复力以及对未来变暖的脆弱性提供了关键见解。