Collaborative Research: High-resolution Reconstruction of Holocene Deglaciation in the Southern Ross Embayment

在对未来海平面的预估中，南极冰盖对未来气候变化的反应被认为是最大的不确定性。对过去冰层波动的了解有助于深入了解冰盖对气候和海平面变化的反应，因此对改进海平面预测至关重要。该项目将研究过去几千年来罗斯海南部的冰川消融，以记录在气候和海平面相对稳定时期南极冰量的波动。我们将帮助量化冰量的变化，提高对冰动力学的理解，并研究对未来海平面变化的影响。该项目将通过研究生的参与来培养未来的科学家，以及将在我们实验室开发研究项目的本科生。先前的研究表明，在全新世早期（距今约11700年前开始），罗斯海的冰川迅速消融，远至Beardmore冰川的南部，随后是更缓慢的消退。然而，全新世后半期的去冰作用仍然没有得到很好的约束，对Beardmore冰川和Scott冰川之间的基准线迁移没有时间上的控制。因此，我们不知道是全新世中期的衰退使斯科特冰川的基准线迅速回到现在的位置，还是在没有显著的气候强迫或海平面上升变化的情况下，冰盖逐渐退缩。后一种可能性引发了对罗斯海搁浅线未来稳定性的担忧。为了解决这个问题，我们将绘制和确定沿海山脉冰川沉积物的年代，这些沉积物限制了利夫冰川和阿蒙森冰川的变薄历史。通过将我们的年表扩展到这些冰川口的浮冰水平，我们将确定它们从冰川最大值到现在的变薄历史，以及罗斯海搁浅线沿着横贯南极山脉向南的迁移。高分辨率测年将来自沿高程样带收集的不稳定物的铍-10表面暴露年龄，以及来自前冰坝池塘的海岸线内藻类的碳-14测年。已经特别选择了地点，以便对这两种测年方法进行密切比较，这将限制南极铍-10的产量。

The response of the Antarctic Ice Sheet to future climatic changes is recognized as the greatest uncertainty in projections of future sea level. An understanding of past ice fluctuations affords insight into ice-sheet response to climate and sea-level change and thus is critical for improving sea-level predictions. This project will examine deglaciation of the southern Ross Sea over the past few thousand years to document oscillations in Antarctic ice volume during a period of relatively stable climate and sea level. We will help quantify changes in ice volume, improve understanding of the ice dynamics responsible, and examine the implications for future sea-level change. The project will train future scientists through participation of graduate students, as well as undergraduates who will develop research projects in our laboratories.Previous research indicates rapid Ross Sea deglaciation as far south as Beardmore Glacier early in the Holocene epoch (which began approximately 11,700 years before present), followed by more gradual recession. However, deglaciation in the later half of the Holocene remains poorly constrained, with no chronological control on grounding-line migration between Beardmore and Scott Glaciers. Thus, we do not know if mid-Holocene recession drove the grounding line rapidly back to its present position at Scott Glacier, or if the ice sheet withdrew gradually in the absence of significant climate forcing or eustatic sea level change. The latter possibility raises concerns for future stability of the Ross Sea grounding line. To address this question, we will map and date glacial deposits on coastal mountains that constrain the thinning history of Liv and Amundsen Glaciers. By extending our chronology down to the level of floating ice at the mouths of these glaciers, we will date their thinning history from glacial maximum to present, as well as migration of the Ross Sea grounding line southwards along the Transantarctic Mountains. High-resolution dating will come from Beryllium-10 surface-exposure ages of erratics collected along elevation transects, as well as Carbon-14 dates of algae within shorelines from former ice-dammed ponds. Sites have been chosen specifically to allow close comparison of these two dating methods, which will afford constraints on Antarctic Beryllium-10 production rates.