Is ice loss from West Antarctica driven by ocean forcing or ice and ocean feedbacks?

南极洲西部的冰损失是由海洋强迫还是冰和海洋反馈驱动的？

• 批准号: NE/M001660/1
• 负责人: Paul Holland
• 金额: $ 39.38万
• 依托单位: British Antarctic Survey
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2014
• 资助国家: 英国
• 起止时间: 2014 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FM001660%2F1
• 关键词: ice; loss; West; Antarctica; driven

The Antarctic Ice Sheet is a mass of ice larger than Europe, in some places several kilometres from top to bottom. Fed by snowfall over its interior, it spreads out under its own weight, going afloat at its edge in the form of enormous ice shelves with areas ranging from that of Greater London to that of France. The ice shelves are then melted from below by waters from the Southern Ocean. The inputs and outputs of the system are so massive that even very small imbalances can have catastrophic effects on global sea level: the portion of Antarctica known as the West Antarctic Ice Sheet (WAIS), suspected unstable due to the shape of its underlying bedrock, would contribute 3-5 m of sea level rise were it to collapse completely.Satellite observations have shown that some of the fast-flowing outlet glaciers that carry ice out of Antarctica have sped up dramatically. Pine Island Glacier, which drains a significant portion of WAIS, has nearly doubled its speed in the last several decades, creating a large negative imbalance for the ice sheet. The acceleration is thought to be connected to the high under-ice shelf melt rates observed in the region. This melting reduces the ability of the Pine Island Ice Shelf to hold back the glacier feeding it. Increased ice-shelf melt rates are possibly due to warming oceans; but recent studies suggest that melting could actually be strongly dependent on ice shelf and ice sheet behaviour as well. Additionally, a recent glaciological modelling study suggests a "tipping point" may have been crossed, and that ice retreat, though triggered by oceans, is now self-perpetuating regardless of melting. Determining whether the observed retreat is due to ongoing climate forcing, or to feedbacks of the coupled ice-ocean system, is of utmost importance to predicting (and if possible mitigating) future sea level contributions from WAIS.In the proposed work we will address this question through the development of a sophisticated computer model of interacting ice sheet and oceans, and by investigation of the processes involved in ice retreat through controlled modelling experiments. Idealized experiments of ice-ocean interactions will lead up to a realistic modelling study of Pine Island Glacier, designed to assess the relative importance of forcing and feedback in its observed retreat.This study will be unprecedented in terms of the tools developed, the experiments undertaken, and the knowledge gained. Presently no numerical model exists that can fully represent the close interaction between ice sheets, ice shelves, and the ocean circulating beneath them. Furthermore the ice and ocean codes, as well as being ideally suited for coupling together, share properties that will allow for in-depth investigation of model sensitivity and controls, and for the incorporation of ice-sheet observations in a physically consistent manner, vastly improving the reliability of results.

南极冰盖是比欧洲大的冰块，在某些地方从上到下几公里。由于内部的降雪供应，它以自身的体重散布，以巨大的冰架形式在边缘散布，区域从大伦敦到法国的区域。然后，冰架从南大洋的水上从下面融化。 The inputs and outputs of the system are so massive that even very small imbalances can have catastrophic effects on global sea level: the portion of Antarctica known as the West Antarctic Ice Sheet (WAIS), suspected unstable due to the shape of its underlying bedrock, would contribute 3-5 m of sea level rise were it to collapse completely.Satellite observations have shown that some of the fast-flowing outlet glaciers that carry ice南极从南极大加速。派恩岛冰川（Pine Island Glacier）耗尽了很大一部分WAIS，在过去的几十年中，其速度几乎翻了一番，对冰盖造成了巨大的负面失衡。该加速度被认为与在该地区观察到的高冰架融化速率相关。这种融化降低了松树岛冰架阻止冰川喂食它的能力。冰架融化速率的提高可能是由于海洋变暖。但是最近的研究表明，熔化实际上也可以很大程度上依赖于冰架和冰盖行为。此外，最近的一项冰科建模研究表明，可能已经越过“临界点”，尽管冰撤退虽然是由海洋触发的，但无论融化如何，它都在自我延续。确定观察到的撤退是由于持续的气候强迫或耦合冰山系统的反馈，对于预测（如果可能减轻）WAIS的未来海平面贡献至关重要。在拟议的工作中，我们将通过与互动的冰台和海洋进行了互动的互动式互动模型来解决此问题，从而解决了这一问题。冰山相互作用的理想化实验将导致对派恩岛冰川的现实建模研究，旨在评估在其观察到的静修中强迫和反馈的相对重要性。这项研究将在开发的工具，实验和知识获得的工具上前所未有。目前，没有数值模型可以完全代表冰盖，冰架和在其下方循环的海洋之间的密切相互作用。此外，冰和海洋法规以及非常适合共同耦合的理想之处，共享属性，可以深入研究模型灵敏度和控制性，以及以物理一致的方式纳入冰盖观测，从而极大地提高了结果的可靠性。

项目成果

West Antarctic ice loss influenced by internal climate variability and anthropogenic forcing

• DOI: 10.1038/s41561-019-0420-9
• 发表时间: 2019-09-01
• 期刊: NATURE GEOSCIENCE
• 影响因子: 18.3
• 作者: Holland, Paul R.;Bracegirdle, Thomas J.;Steig, Eric J.
• 通讯作者: Steig, Eric J.

Ocean-Forced Ice-Shelf Thinning in a Synchronously Coupled Ice-Ocean Model

• DOI: 10.1002/2017jc013251
• 发表时间: 2018-02-01
• 期刊: JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS
• 影响因子: 3.6
• 作者: Jordan, James R.;Holland, Paul R.;Jenkins, Adrian
• 通讯作者: Jenkins, Adrian

The Response of Ice Sheets to Climate Variability

冰盖对气候变化的响应

• DOI: 10.1002/2017gl075745
• 发表时间: 2017
• 期刊: Geophysical Research Letters
• 影响因子: 5.2
• 作者: Snow K