Collaborative Research: Potential Direct Geologic Constraint of Ice Sheet Thickness in the Central Transantarctic Mountains during the Pliocene Warm Period

合作研究：上新世温暖期横贯南极中部山脉冰盖厚度的潜在直接地质约束

• 批准号: 1443329
• 负责人: Gregory Balco
• 金额: $ 9.81万
• 依托单位: Berkeley Geochronology Center
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-09-01 至 2020-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1443329&HistoricalAwards=false
• 关键词: Collaborative; Research; Potential; Direct; Geologic

This investigation will reconstruct past behavior of the East Antarctic Ice Sheet during periods of warmer-than-present climate, such as the Pliocene, in order to better project the likely response of Earth's largest ice sheet to anthropogenic warming. Containing the equivalent of ~55 m sea-level rise, the future evolution of the East Antarctic Ice Sheet has clear societal ramifications on a global scale as temperatures continue to rise. Therefore, determining ice-sheet sensitivity to climate on the scale predicted for the next two centuries is a matter of increasing urgency, particularly in light of evidence suggesting the East Antarctic Ice Sheet is more dynamic than previously thought. This research will provide a terrestrial geologic record of long-term ice-sheet behavior from sites immediately adjacent the East Antarctic Ice Sheet in the Transantarctic Mountains, with which the project will help ascertain how the ice sheet responded to past warm periods. The project will focus primarily on the Pliocene warm period, 5 to 3 million years ago, as this represents the closest analogue to 21st Century climate conditions.The proposed research will investigate glacial deposits corresponding to the East Antarctic Ice Sheet in the central Transantarctic Mountains in order to expand the geologic record of past ice-sheet behavior. The overarching research objectives are to improve understanding of the East Antarctic Ice Sheet's configuration during periods of warmer-than-present climate, such as the Pliocene warm period, and to determine whether the ice sheet underwent significant volume changes or remained relatively stable in response to warming. To address these goals, the investigation will map and date glacial deposits preserved at mountain sites immediately adjacent the ice sheet. Specifically, we will: (i) employ multiple cosmogenic nuclides (10Be, 26Al, 21Ne) to establish more fully ice-thickness histories for the upper Shackleton and Beardmore Glaciers, where they exit the ice sheet; (ii) use this record to identify periods during which the East Antarctic Ice Sheet was at least as extensive as today; and (iii) use these data to assess long-term ice-sheet variability in East Antarctica, with particular emphasis on Pliocene warm episodes. This research will require Antarctic fieldwork, glacial-geologic mapping, and cosmogenic surface-exposure dating.

这项调查将重建过去南极东部冰盖在比现在更温暖的气候时期（如上新世）的行为，以便更好地预测地球上最大的冰盖对人为变暖的可能反应。随着气温继续上升，南极东部冰盖的未来演变将在全球范围内产生明显的社会影响，相当于海平面上升约55米。因此，在未来两个世纪预测的尺度上确定冰盖对气候的敏感性是一个日益紧迫的问题，特别是考虑到有证据表明南极东部冰盖比以前认为的更具动态性。这项研究将提供南极横贯山脉中紧邻南极东部冰盖的地点的长期冰盖行为的陆地地质记录，该项目将有助于确定冰盖对过去温暖时期的反应。该项目将主要关注500万至300万年前的上新世暖期，因为这是与21世纪气候条件最相似的时期。拟议的研究将调查南极横贯山脉中部与南极东部冰盖相对应的冰川沉积物，以扩大过去冰盖行为的地质记录。总体研究目标是提高对南极东部冰盖在比现在更暖的气候时期（如上新世暖期）的结构的理解，并确定冰盖是否经历了显著的体积变化或保持相对稳定以响应变暖。为了实现这些目标，这项调查将绘制冰川沉积物的地图，并确定保存在紧邻冰盖的山区遗址的冰川沉积物的日期。具体来说，我们将：(i)使用多种宇宙形成核素（10Be, 26Al, 21Ne）来建立更完整的沙克尔顿冰川和比尔德莫尔冰川上部的冰厚历史，它们在那里退出冰盖；（ii）利用这一记录确定南极东部冰盖至少与今天一样广泛的时期；（iii）利用这些数据评估东南极洲的长期冰盖变化，特别强调上新世暖期。这项研究将需要南极实地考察、冰川地质测绘和宇宙起源地表暴露年代测定。