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Assessing the sensitivity of major East Antarctic outlet glaciers to recent and future changes in the ocean-climate system

评估主要东南极出口冰川对海洋气候系统近期和未来变化的敏感性

基本信息

批准号：
NE/R000824/1
负责人：
Chris Stokes
金额：
$ 41.31万
依托单位：
Durham University
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2018
资助国家：
英国
起止时间：
2018 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FR000824%2F1
关键词：
Assessing sensitivity major East Antarctic

项目摘要

The Earth's atmosphere and oceans are warming as a result of increased concentrations of greenhouse gases. Glaciers melt when the Earth warms and water that was stored as ice on land runs off into the ocean and increases sea-level. Over the last few decades, measurements have shown that sea-level is increasing by around 3 millimetres per year, and that this is due to the expansion of the warmer ocean water and the runoff from glaciers. In the 20th century, the sea-level contribution from melting ice was dominated by small mountain glaciers and ice caps, but it is now known that the vast ice sheets in Greenland and Antarctica are contributing an equally large amount to sea level and that their contribution is accelerating. One of the main ways in which ice sheets contribute to sea-level (especially in Antarctica, but also in Greenland) is through rapidly-flowing outlet glaciers that transfer ice from the interior to the margins, where it breaks off as icebergs. Recent measurements, mostly using observations from satellites, have shown that many outlet glaciers are thinning and retreating and, in some cases, their flow is also accelerating. This helps explain why their ice discharge is increasing. These changes in outlet glaciers are complex, but scientists think that they are caused by warmer ocean temperatures and, in some cases, by the landscapes underneath the outlet glaciers, especially if they flow through deep valleys that are below sea level and get deeper inland under the ice. The most dramatic changes have been observed in Greenland and West Antarctica, which store around 6 and 4 m of sea-level equivalent, respectively. Thus, unlike smaller mountain glaciers, changes in outlet glaciers could contribute several metres to global sea-level, possibly over quite short time-scales (just a few centuries according to some predictions). It is for this reason that a lot of research is aimed at monitoring outlet glaciers in Greenland and West Antarctica. Most of the ice in Antarctica is, however, stored in East Antarctica, which holds a sea-level equivalent of around 53 m. It is perhaps surprising, therefore, that there are so few measurements of outlet glaciers in the East Antarctic Ice Sheet (EAIS), but this is probably because it was traditionally thought to be much more stable than West Antarctica. Recently, however, evidence has been uncovered which indicates that parts of the EAIS, especially those parts that that overlie deep valleys and basins, might have retreated quite dramatically when climate was slightly warmer in the past. Moreover, observations of just one or two glaciers in these same regions indicates that they are also thinning and retreating, similar to those in Greenland and West Antarctica. Thus, there is a small but growing body of evidence suggesting that some parts of the EAIS might also be vulnerable to global warming. Unfortunately, we do not have enough observations to know exactly what is happening in different parts of East Antarctica and there is a large amount of uncertainty about whether its outlet glaciers are sensitive to changes in the ocean and/or atmosphere. This project has been designed to specifically address this uncertainty. We will use satellite measurements to determine recent changes on some of the largest and most important outlet glaciers from different regions of East Antarctica. This will tell us where the most dramatic changes have taken place and which areas are more stable. We will then use a computer model to see what kind of changes would take place if air or ocean temperatures increase in the future. This will tell us which glaciers are most sensitive and what their contribution to sea level might be over the next few centuries. Even where glaciers are currently stable, it is important to know by how much climate would need to change before they might react. This new knowledge is vitally important to help governments plan for future changes in sea-level.

由于温室气体浓度的增加，地球的大气层和海洋正在变暖。当地球变暖时，冰川融化，陆地上储存的冰流入海洋，海平面上升。在过去几十年中，测量结果表明，海平面每年上升约3毫米，这是由于温暖的海水和冰川径流的扩张。在20世纪，冰川融化对海平面的贡献主要是小型山地冰川和冰盖，但现在人们知道，格陵兰岛和南极洲的巨大冰盖对海平面的贡献同样大，而且它们的贡献正在加速。冰盖对海平面的贡献（特别是在南极洲，但也在格陵兰岛）的主要方式之一是通过快速流动的出口冰川将冰从内部转移到边缘，在那里它作为冰山断裂。最近的测量，主要是利用卫星观测，表明许多出口冰川正在变薄和退缩，在某些情况下，它们的流动也在加速。这有助于解释为什么他们的冰排放量正在增加。出口冰川的这些变化是复杂的，但科学家们认为，它们是由海洋温度升高引起的，在某些情况下，是由出口冰川下的景观引起的，特别是如果它们流过低于海平面的深谷，并在冰下深入内陆。格陵兰岛和南极洲西部的变化最大，分别储存了相当于海平面6米和4米的水。因此，与较小的山地冰川不同，出口冰川的变化可能在很短的时间尺度内（根据一些预测，只有几个世纪）使全球海平面上升几米。正是由于这个原因，许多研究的目的是监测格陵兰岛和南极洲西部的出口冰川。然而，南极洲的大部分冰都储存在南极洲东部，那里的海平面相当于53米左右。因此，对东南极冰盖（EAIS）出口冰川的测量如此之少可能令人惊讶，但这可能是因为传统上认为它比西南极洲稳定得多。然而，最近发现的证据表明，EAIS的部分地区，特别是那些覆盖在深谷和盆地上的部分，可能在过去气候稍微温暖时发生了相当大的退缩。此外，对这些地区一两个冰川的观察表明，它们也在变薄和退缩，类似于格陵兰岛和南极洲西部的冰川。因此，有一个小但越来越多的证据表明，EAIS的某些部分也可能容易受到全球变暖的影响。不幸的是，我们没有足够的观测数据来确切地了解南极洲东部不同地区发生的情况，而且其出口冰川是否对海洋和/或大气的变化敏感也存在很大的不确定性。该项目旨在专门解决这种不确定性。我们将使用卫星测量来确定东南极洲不同地区一些最大和最重要的出口冰川的最新变化。这将告诉我们哪些地方发生了最剧烈的变化，哪些地区更稳定。然后，我们将使用计算机模型来观察如果未来空气或海洋温度升高会发生什么样的变化。这将告诉我们哪些冰川是最敏感的，以及它们在未来几个世纪对海平面的贡献。即使在冰川目前稳定的地方，重要的是要知道在它们可能做出反应之前，气候需要发生多大的变化。这些新知识对于帮助政府规划未来海平面的变化至关重要。

项目成果

期刊论文数量（10）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Velocity increases at Cook Glacier, East Antarctica linked to ice shelf loss and a subglacial flood event

东南极洲库克冰川速度增加与冰架消失和冰下洪水事件有关

DOI：
10.5194/tc-2018-107
发表时间：
2018
期刊：
影响因子：
0
作者：
Miles B
通讯作者：
Miles B

Increased warm water intrusions could cause mass loss in East Antarctica during the next 200 years.

DOI：
10.1038/s41467-023-37553-2
发表时间：
2023-04-01
期刊：
NATURE COMMUNICATIONS
影响因子：
16.6
作者：
Jordan, James R.;Miles, B. W. J.;Gudmundsson, G. H.;Jamieson, S. S. R.;Jenkins, A.;Stokes, C. R.
通讯作者：
Stokes, C. R.

Large interannual variability in supraglacial lakes around East Antarctica.