Greenland Ice Sheet and sea-level response under climate change from AD 1600 to 2100

公元1600年至2100年气候变化下的格陵兰冰盖和海平面响应

• 批准号: NE/Y000129/1
• 负责人: Edward Hanna
• 金额: $ 105.28万
• 依托单位: University of Lincoln
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2024
• 资助国家: 英国
• 起止时间: 2024 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FY000129%2F1
• 关键词: Greenland; Ice; Sheet; sea; level

The Greenland Ice Sheet contains enough mass to raise global sea-level by seven metres. Greenland Ice Sheet mass loss arising from global warming is currently the main icy contributor to global sea-level rise and could contribute several tens of centimetres to global sea level by the year 2100, although this prediction is highly uncertain. Most recent studies show that surface mass balance (defined as net solid precipitation minus surface meltwater that runs off from the ice sheet) is the main part of 21st century Greenland Ice Sheet mass change; yet key gaps remain in our knowledge and understanding of Greenland Ice Sheet change at the multi-century timescale. Improved information on surface mass balance changes over space and time is needed to improve the reliability of computer models of ice-sheet flow and loss of ice via calving of icebergs (called ice dynamics). The present limited understanding of recent surface mass balance change resulting from the lack of constrained computer simulations, especially for time periods before the last 50 years or so, propagates through to unreliable estimates of future total mass balance (i.e. the sum of surface mass balance and ice dynamical changes) and therefore projections of sea level rise. Most current Greenland Ice Sheet surface mass balance datasets do not extend back before around 1900, while the more sophisticated surface mass balance models tend to focus on relatively short periods since 1960 due to unavoidable requirements of large amounts of reliable, complex input data (for example those relating to surface heat and energy flows between the ice sheet's surface and the atmosphere) which are typically unavailable before the 1960s. Also, estimates of the ice dynamic portion of ice-sheet mass change are based on statistical relationships of ice output with recent climatology, which is unlikely to be representative of the pre-instrumental period or the future. Therefore, bridging the major gap in the understanding of Greenland Ice Sheet-climate interactions and effect on sea-level during the large climate shifts between Little Ice Age (around 1600 to 1850) and the 20th/21st Century is urgently needed to reduce the significant uncertainty propagating through to the global sea-level contribution of Greenland Ice Sheet changes during the rest of the Twenty First Century. Our proposal combines a wide range of models, observations and scientific expertise to address this key knowledge gap.This project will produce estimates of past and future Greenland Ice Sheet surface mass balance and dynamic ice changes using cutting-edge climate and ice sheet models and datasets and mathematical evaluation of the uncertainties in these. The main aim of the proposed work is to produce a novel constrained surface and full mass balance history of the Greenland Ice Sheet from 1600 to 2021 and Greenland Ice Sheet mass balance projections to 2100, and to assess the resulting contribution to historical and future global sea-level. The reconstruction of the Greenland Ice Sheet surface mass balance back to 1600, for a period where such records are largely lacking, will quadruple the length of the existing published surface mass balance record, and form the basis of an improved understanding of the ice sheet's history and sensitivity to climate change. Our approach offers several key methodological improvements - most notably its inclusion of all the main outlet glaciers and determination of a range of most likely results - over previous attempts to forecast future changes in the Greenland Ice Sheet. We will combine our Greenland Ice Sheet surface mass balance projections with the total mass balance projections from our ice-sheet modelling work to calculate the relative contributions of surface mass balance and ice dynamics in space and time to total mass changes, and to determine their sensitivity to ongoing human-driven climate change during 1600-2100.

格陵兰冰盖的质量足以使全球海平面上升七米。全球变暖导致的格陵兰冰盖质量损失目前是全球海平面上升的主要原因，到 2100 年，全球海平面可能会上升数十厘米，尽管这一预测具有很大的不确定性。最近的研究表明，表面质量平衡（定义为净固体降水减去从冰盖流出的表面融水）是21世纪格陵兰冰盖质量变化的主要部分；然而，我们对格陵兰冰盖在多个世纪的时间尺度上的变化的认识和理解仍然存在重大差距。需要改进有关表面质量平衡随空间和时间变化的信息，以提高冰盖流动和冰山崩解导致的冰损失（称为冰动力学）的计算机模型的可靠性。由于缺乏受约束的计算机模拟，目前对近期表面质量平衡变化的了解有限，尤其是在过去 50 年左右的时间段内，这会导致对未来总质量平衡（即表面质量平衡和表面质量平衡的总和）的不可靠估计。冰动态变化），从而预测海平面上升。目前大多数格陵兰冰盖表面质量平衡数据集都不会追溯到 1900 年左右，而更复杂的表面质量平衡模型往往侧重于 1960 年以来相对较短的时期，因为不可避免地需要大量可靠、复杂的输入数据（例如那些与表面热量以及冰盖表面和大气之间的能量流有关的数据）在 20 世纪 60 年代之前通常是无法获得的。此外，对冰盖质量变化的冰动态部分的估计是基于冰输出与最近气候学的统计关系，这不太可能代表仪器仪表前时期或未来。因此，迫切需要弥合小冰河时期（约 1600 年至 1850 年）和 20 世纪/21 世纪之间气候大转变期间格陵兰冰盖与气候相互作用和对海平面影响的主要认识差距，以减少显着的气候变化。在二十一世纪剩余时间里，不确定性传播到格陵兰冰盖变化对全球海平面的影响。我们的提案结合了广泛的模型、观测和科学专业知识，以解决这一关键的知识差距。该项目将使用尖端的气候和冰盖模型和数据集对过去和未来的格陵兰冰盖表面质量平衡和动态冰变化进行估计并对这些不确定性进行数学评估。拟议工作的主要目的是生成格陵兰冰盖从 1600 年到 2021 年的新颖约束表面和完整质量平衡历史以及格陵兰冰盖到 2100 年的质量平衡预测，并评估由此产生的对历史和未来全球海洋的贡献-等级。格陵兰冰盖表面质量平衡的重建可追溯至 1600 年（这一时期基本上缺乏此类记录），这将使现有已发布的表面质量平衡记录的长度增加四倍，并为更好地了解冰盖历史奠定基础以及对气候变化的敏感性。与之前预测格陵兰冰盖未来变化的尝试相比，我们的方法提供了几项关键的方法改进，最值得注意的是它包含了所有主要出口冰川并确定了一系列最可能的结果。我们将把格陵兰冰盖表面质量平衡预测与冰盖建模工作中的总质量平衡预测结合起来，计算表面质量平衡和冰动力学在空间和时间上对总质量变化的相对贡献，并确定它们的敏感性1600-2100年间持续的人类驱动的气候变化。