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

南极冰盖对未来气候变化的反应被认为是预测未来海平面的最大不确定性。了解过去的冰波动有助于洞察冰盖对气候和海平面变化的反应，因此对于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的时期南极冰量的振荡。我们将帮助量化冰量的变化，提高对相关冰动力学的理解，并研究对未来海平面变化的影响。该项目将通过研究生和本科生的参与来培养未来的科学家，这些本科生将在我们的实验室开展研究项目。以前的研究表明，罗斯海冰川的快速消融在全新世早期(大约开始于现在的11,700年前)最南端的比尔德莫尔冰川，随后是更缓慢的衰退。然而，全新世后半期的冰川消融仍然没有得到很好的控制，比尔德莫尔冰川和斯科特冰川之间的基准线迁移没有时间上的控制。因此，我们不知道是中全新世经济衰退使接地线迅速回到斯科特冰川现在的位置，还是在没有显著的气候强迫或海平面变化的情况下，冰盖逐渐退缩。后一种可能性引发了对罗斯海接地线未来稳定性的担忧。为了解决这个问题，我们将绘制制约Liv和Amundsen冰川变薄历史的沿海山脉上的冰川沉积并确定日期。通过将我们的年表向下延伸到这些冰川入海口的浮冰水平，我们将确定它们从冰川顶峰到现在的变薄历史，以及罗斯海接地线沿横贯北极山脉向南迁移的时间。高分辨率测年将来自沿着高程断面收集的反复无常的铍-10表面暴露年龄，以及以前冰坝池塘海岸线上藻类的碳-14年龄。选址是为了能够对这两种测年方法进行近距离比较，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.