Late Neogene to Quaternary climate and ice sheet history of West Antarctica

新近纪晚期至第四纪气候与西南极洲冰盖历史

• 批准号: 447431185
• 负责人: Professor Dr. Thorsten Bauersachs
• 金额: --
• 依托单位: Arbeitsgruppe Organische Geochemie
• 依托单位国家: 德国
• 项目类别: Infrastructure Priority Programmes
• 财政年份: 2020
• 资助国家: 德国
• 起止时间: 2019-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/447431185?language=en
• 关键词: Late; Neogene; Quaternary; climate; ice

The West Antarctic Ice Sheet (WAIS) holds an ice volume of 2.2 million km3 and thereby contributes ~10% to the ice volume of Antarctica. Rates of mass loss from the WAIS have dramatically accelerated in the recent past and at present the WAIS is the fastest melting region of the Antarctic continent. Current estimates suggest that the WAIS contributed about 86% to the total ice mass loss of Antarctica over the last two decades and if melting continues at its present pace, it may lead to a global sea level rise by up to one meter until the end of this century. A complete collapse of the WAIS may result in a global sea level rise of up to 6 m. Model predictions indicate that such collapses may have occurred repeatedly since the late Miocene and unfold within a geologically relative short timespan of only several hundreds of years. Such model simulations also suggest that a threshold leading to the collapse of the WAIS may have been crossed already and that much of the ice sheet could be lost even under relatively moderate greenhouse gas emission scenarios. These model predictions, however, show large uncertainties in terms of timing and absolute volume of ice sheet loss. Proxy records that yield information on the past waxing and waning of the WAIS may help in improving our understanding on the future behaviour of this very vulnerable but globally important region of our planet. Such proxy records may specifically be used for constraining and testing ice sheet models that aim to predict future WAIS behaviour and the potential contribution of the WAIS to global sea level rise. Yet proxy records defining the deep time ice sheet history of the WAIS are largely lacking at present. Sediments obtained from the continental rise of the Amundsen Sea during IODP Expedition 379: “Amundsen Sea West Antarctic Ice Sheet History” provide the first continuous records of climate and ice sheet dynamics of the WAIS that date back to ~6.8 Ma and will allow reconstructing spatiotemporal variations of the ice sheet extent in an as yet unprecedented resolution. In the project proposed here, we plan to employ a multi-proxy approach, combining bulk-geochemical, isotope and lipid biomarker techniques, to investigate the response of the WAIS to changing environmental conditions and determine to which extent partial to full collapses of the WAIS have occurred previously and on which time scales. In particular, we aim to generate the first continuous late Miocene to Quaternary paleotemperature record for this region of the global oceans and test the hypothesis that the retreat of the ice sheet is directly controlled by incursions of relatively warm circumpolar deep water onto the West Antarctic shelf. In addition, we plan to determine the response of the aquatic and terrestrial ecosystems to advances and retreats of ice masses and explore whether these systems will act as sources or sinks of carbon under future scenarios of global warming.

南极西部冰盖（WAIS）的冰量为220万立方千米，占南极洲冰量的10%。在最近的过去，西洋洲的质量损失速度急剧加快，目前西洋洲是南极大陆融化最快的地区。目前的估计表明，在过去20年里，WAIS造成了南极洲总冰量损失的86%，如果继续以目前的速度融化，到本世纪末，它可能导致全球海平面上升1米。西洋带的完全崩塌可能导致全球海平面上升6米。模型预测表明，自中新世晚期以来，这种崩塌可能反复发生，并在几百年的相对较短的地质时间内展开。这样的模型模拟还表明，可能已经越过了导致WAIS崩溃的阈值，即使在相对温和的温室气体排放情景下，大部分冰盖也可能消失。然而，这些模式预测在冰盖损失的时间和绝对体积方面显示出很大的不确定性。代理记录提供了关于西海生态系统过去消长的信息，这可能有助于我们更好地了解地球上这个非常脆弱但在全球具有重要意义的地区未来的行为。此类代理记录可专门用于约束和测试冰盖模型，这些模型旨在预测未来的WAIS行为以及WAIS对全球海平面上升的潜在贡献。然而，目前在很大程度上还缺乏界定西海地区深层冰原历史的代用记录。在IODP第379次考察期间，从阿蒙森海大陆隆起处获得的沉积物：“阿蒙森海西南极冰盖历史”提供了可追溯到~6.8 Ma的WAIS气候和冰盖动态的第一个连续记录，并将以前所未有的分辨率重建冰盖范围的时空变化。在这里提出的项目中，我们计划采用多代理方法，结合体积地球化学，同位素和脂质生物标志物技术，研究WAIS对不断变化的环境条件的响应，并确定WAIS之前发生的部分或完全崩塌的程度和时间尺度。特别是，我们的目标是为这一地区的全球海洋产生第一个连续的晚中新世到第四纪的古温度记录，并测试冰盖的退缩是由相对温暖的环极深水侵入南极西部大陆架直接控制的假设。此外，我们计划确定水生和陆地生态系统对冰块前进和后退的响应，并探索这些系统在未来全球变暖情景下是作为碳源还是汇。