Greenland in a warmer climate: What controls the advance & retreat of the NE Greenland Ice Stream

气候变暖的格陵兰岛：是什么控制着前进

• 批准号: NE/N011228/1
• 负责人: David Roberts
• 金额: $ 71.31万
• 依托单位: Durham University
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2016
• 资助国家: 英国
• 起止时间: 2016 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FN011228%2F1
• 关键词: Greenland; warmer; climate; What; controls

Over the past decade the Greenland ice sheet has thinned at an accelerating rate and is currently the largest single contributor to global sea-level rise. Understanding the likely rate and magnitude of future change matters because accurate projections of sea-level rise are necessary if governments are to plan for the future in a warming world and develop sustainable coastal defence strategies.A significant portion of Greenland's contribution to sea-level rise has been associated with the speed-up and melting of an increased number of fast-flowing outlet glaciers. Rapid thinning of these glaciers has coincided with increases in air and ocean temperatures, suggesting that they are sensitive and responsive to these parameters. However, although various mechanisms related to atmospheric and oceanic forcing have been proposed to explain the recent thinning, there exist large uncertainties in the relative importance of and interplay between each of these and the ice sheet response to them over longer timescales. Without this crucial information output from the current generation of ice sheet models has limitations and there is potential for significant errors in sea-level rise projections.This research will directly address this critical gap in our understanding by reconstructing the past behaviour of the Northeast Greenland Ice Stream (NEGIS) over the past 10,000 years. NEGIS is of particular interest because recent studies show that this cold, High Arctic region of the ice sheet has started to undergo sustained thinning after more than 25 years of relative stability. This has raised concerns that rapid inland retreat is already underway and could lead to drawdown of the NEGIS catchment. Complete collapse of its drainage basin would raise sea-level by ~1.4 m (equivalent to the combined Pine Island-Thwaites catchment in Antarctica) posing a major hazard for coastal populations. NEGIS provides an unparalleled opportunity to investigate the response of an ice stream to past change (oceanic and atmospheric warming), because there is evidence that it underwent dramatic retreat (and then advance) during the Holocene Thermal Maximum (a period of increased air temperatures analogous to that predicted for late 21st century). To achieve this we have assembled an experienced team who will generate a detailed record of changes in NEGIS geometry, and the contemporaneous atmospheric, oceanic and relative sea level changes. We will reconstruct ice stream configuration (thickness, extent) from marine and terrestrial data, and produce high-resolution records of oceanic and atmospheric temperatures and relative sea level. Using a state-of-the-art ice sheet model (BISICLES), these data will be used to test the sensitivity of the ice stream to different forcing mechanisms at 100-1000 year timescales. Our chosen timescale will allow us to differentiate short term 'noise' from long term trends, something that has been recognised as a potential issue, which is not possible from investigations of contemporary margin fluctuations derived from a few decades of instrumental records. Ultimately our project will deliver significant improvements in our understanding of the sensitivity of the ice sheet to various forcing mechanisms that will help to underpin sea-level rise projections, shape policy on coastal defence and protect future generations.The project has significant added value in that we will work within a funded European programme 'Greenland Ice Sheet/Ocean Interaction and Fram Strait Fluxes' and has confirmed funded logistical support through the Alfred Wegener Institute, Germany and a 50 day cruise on the RV Polarstern (2016) to this remote area.

在过去十年中，格陵兰冰盖以加速的速度变薄，目前是全球海平面上升的最大单一因素。了解未来变化的可能速率和幅度很重要，因为如果政府要在变暖的世界中为未来做计划并制定可持续的海岸防御战略，就必须准确预测海平面上升。格陵兰岛对海平面上升的贡献很大一部分与越来越多的快速流动的出口冰川的加速和融化有关。这些冰川的迅速变薄与空气和海洋温度的上升相吻合，这表明它们对这些参数很敏感。然而，虽然已经提出了各种机制，大气和海洋强迫解释最近的变薄，存在很大的不确定性，在相对重要性和相互作用，这些和冰盖对它们的反应在较长的时间尺度。如果没有这一关键信息，当前一代冰盖模型的输出具有局限性，并且在海平面上升预测中存在重大错误的可能性。这项研究将通过重建过去1万年来东北格陵兰冰流（NEGIS）的过去行为，直接解决我们理解中的这一关键差距。NEGIS特别令人感兴趣，因为最近的研究表明，这个寒冷的高北极地区的冰盖在经过25年以上的相对稳定之后，已经开始持续变薄。这引起了人们的担忧，即内陆的快速撤退已经在进行中，可能导致NEGIS集水区的缩减。其流域的完全崩溃将使海平面上升约1.4米（相当于南极洲Pine Island-Thwaites集水区的总和），对沿海人口构成重大危险。NEGIS为研究冰流对过去变化（海洋和大气变暖）的反应提供了一个无与伦比的机会，因为有证据表明，它在全新世最高温度（一个类似于21世纪世纪后期预测的气温升高的时期）期间经历了戏剧性的撤退（然后前进）。为了实现这一目标，我们组建了一个经验丰富的团队，他们将详细记录NEGIS几何形状的变化，以及同期的大气，海洋和相对海平面的变化。我们将根据海洋和陆地数据重建冰流结构（厚度，范围），并制作海洋和大气温度以及相对海平面的高分辨率记录。使用最先进的冰盖模型（BISICLES），这些数据将用于测试冰流在100-1000年时间尺度上对不同强迫机制的敏感性。我们选择的时间尺度将使我们能够区分短期的“噪音”从长期的趋势，这已被公认为一个潜在的问题，这是不可能从调查的当代利润波动来自几十年的仪器记录。最终，我们的项目将大大提高我们对冰盖对各种强迫机制的敏感性的理解，这将有助于支持海平面上升预测，该项目具有重要的附加价值，因为我们将在一个由欧洲资助的项目“格陵兰冰盖/海洋互动和弗拉姆海峡通量“，并已确认通过阿尔弗雷德·韦格纳研究所，德国和50天的巡航RV Polarstern（2016）到这个偏远地区的资助后勤支持。

项目成果

Holocene Interactions Between Glacier Retreat, Sea Ice Formation, and Atlantic Water Advection at the Inner Northeast Greenland Continental Shelf

• DOI: 10.1029/2020pa004019
• 发表时间: 2020-11
• 期刊: Paleoceanography and Paleoclimatology
• 影响因子: 3.5
• 作者: Nicole Syring;J. Lloyd;R. Stein;K. Fahl;D. Roberts;L. Callard;C. O'cofaigh

The geomorphological record of an ice stream to ice shelf transition in Northeast Greenland

格陵兰岛东北部冰流到冰架过渡的地貌记录

• DOI: 10.1002/esp.5552
• 发表时间: 2023
• 期刊: Earth Surface Processes and Landforms
• 影响因子: 3.3
• 作者: Lane T

Holocene history of the 79° N ice shelf reconstructed from epishelf lake and uplifted glaciomarine sediments

从上层湖和隆起的冰川沉积物重建的北纬79°冰架的全新世历史

• DOI: 10.5194/tc-17-1247-2023
• 发表时间: 2023
• 期刊: The Cryosphere
• 作者: Smith J

Bathymetry constrains ocean heat supply to Greenland's largest glacier tongue

测深限制了格陵兰岛最大冰川舌的海洋热量供应

• DOI: 10.1038/s41561-019-0529-x
• 发表时间: 2020
• 期刊: Nature Geoscience
• 影响因子: 18.3
• 作者: Schaffer J

Direct measurement of warm Atlantic Intermediate Water close to the grounding line of Nioghalvfjerdsfjorden (79° N) Glacier, northeast Greenland

直接测量格陵兰岛东北部 Nioghalvfjerdsfjorden（北纬 79°）冰川接地线附近的温暖大西洋中层水

• DOI: 10.5194/tc-17-1821-2023
• 发表时间: 2023
• 期刊: The Cryosphere
• 作者: Bentley M