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.

南极冰盖（WAIS）的冰量为220万km3，因此对南极的冰量约为10％。在最近的过去，WAIS的质量损失率显着加速，目前，WAIS是南极大陆最快的熔化区域。目前的估计表明，在过去的二十年中，WAI贡献了约86％的冰质量损失，如果在其演示空间中熔化持续，则可能导致全球海平面上升到本世纪末。 WAIS的完全崩溃可能导致全球海平面上升高达6 m。模型预测表明，自中新世晚期以来，这种崩溃可能已经反复发生，并且在地质相对短时间内只有数百年。这种模型模拟还表明，导致WAI崩溃的阈值可能已经越过，即使在相对适度的温室气体排放情况下，大部分冰盖也可能丢失。但是，这些模型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，会产生有关过去打蜡和逐渐减弱的信息的信息，这可能有助于提高我们对这个非常脆弱但全球重要地区的未来行为的理解。可以专门用于限制和测试冰盖模型，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，目前缺乏定义WAIS深度冰期历史的代理记录。从IODP探险期间，Amundsen Sea在379年的持续崛起获得的沉积物：“ Amundsen Sea Sea West Antarctic Ice Speie Speie Stance历史”提供了首次连续记录WAI的气候和冰盖动态的记录，该记录可追溯到〜6.8 MA，并将允许重建冰期冰期范围的空间时间变化，从而在尚未确定的是固定的。在此处提出的项目中，我们计划采用一种多种方法，结合了散装地球化学，同位素和脂质生物标志物技术，以调查WAIS对改变环境条件的响应，并确定以前发生了与WAIS完全崩溃的程度以及在哪些时间范围内发生的。特别是，我们旨在为全球海洋区域的第一个中新世连续到Quaternary Greatemprature记录，并检验以下假设：冰盖的撤退直接由相对温暖的电路深层深水侵入到西南极架子上。此外，我们计划确定水生和陆地生态系统对冰块的进步和撤退的反应，并探讨这些系统是否会在全球变暖的未来情况下充当碳的来源或下沉。