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

格陵兰冰盖的质量足以使全球海平面上升7米。全球变暖造成的格陵兰冰盖质量损失目前是造成全球海平面上升的主要原因，到2100年可能使全球海平面上升几十厘米，尽管这一预测非常不确定。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，我们对格陵兰冰盖变化的认识和理解在多世纪时间尺度上仍然存在关键差距。需要改进关于表面物质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造成的冰损失（称为冰动力学）计算机模型的可靠性。由于缺乏受约束的计算机模拟，目前对最近的表面质量平衡变化的了解有限，特别是在过去50年左右的时间内，传播到对未来总质量平衡（即表面质量平衡和冰动力变化的总和）的不可靠估计，因此对海平面上升的预测。大多数目前的格陵兰冰盖表面质量平衡数据集都没有追溯到1900年左右，而更复杂的表面质量平衡模型往往侧重于自1960年以来相对较短的时期，因为不可避免地需要大量可靠的，复数输入数据（例如与冰盖表面和大气之间的表面热量和能量流动有关的那些）这在20世纪60年代以前是不可能的。此外，估计冰盖质量变化的冰动态部分是基于冰输出与最近的气候学，这是不太可能代表前仪器期间或未来的统计关系。因此，在小冰期（约1600年至1850年）和20/21世纪之间的大气候变化期间，迫切需要弥合格陵兰冰盖-气候相互作用和对海平面影响的理解方面的主要差距，以减少在21世纪剩余时间内传播到格陵兰冰盖变化对全球海平面贡献的重大不确定性。我们的建议结合了广泛的模型，观测和科学专业知识，以解决这一关键的知识差距，该项目将使用先进的气候和冰盖模型和数据集以及对这些不确定性的数学评估，对过去和未来格陵兰冰盖表面质量平衡和动态冰变化进行估计。拟议工作的主要目的是产生一个新的约束表面和完整的质量平衡历史的格陵兰冰盖从1600年到2021年和格陵兰冰盖质量平衡预测到2100年，并评估由此产生的贡献历史和未来的全球海平面。格陵兰冰盖表面质量平衡的重建可以追溯到1600年，这一时期的记录在很大程度上是缺乏的，这将使现有公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的历史和对气候变化的敏感性奠定基础。我们的方法提供了几个关键的方法改进-最值得注意的是它包括所有主要的出口冰川和确定一系列最可能的结果-在以前的尝试，以预测未来的变化在格陵兰冰盖。我们将联合收割机我们的格陵兰冰盖表面质量平衡预测与我们的冰盖建模工作的总质量平衡预测，以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，并确定它们对1600-2100年期间人类驱动的气候变化的敏感性。

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.