Examining the glacial cycle phase space through data-integrated glacial systems modelling

过去是我们通向未来的模糊窗口。通过这个窗口，诱人的差异指向了我们对冰、地球和气候系统耦合的理解的裂痕。过去13万年的冰和气候变化的历史提供了气候系统状态的重大变化以及突然的临界点行为的例子。这个系统变化的动力来源仍然很少被理解。在解释最后一次冰盛期的全球平均海平面(“遗漏”问题)以及大约12.5万年前的最后一次(伊米亚)间冰期海平面上升6-10米的原因方面，也存在令人费解的不足。对潜在气候变化的科学评估在很大程度上依赖于气候模型。尽管对模型来说，复制当今的气候是一项具有挑战性的测试，但这只是一项有限的测试，因为这些模型已经进行了调整，以适应目前的情况。为了回答与气候系统潜在的重大变化相关的问题(特别是所谓的临界点)，最好对照过去对模型进行测试。对这些测试来说，关键是对过去地形、冰盖和相关的融化水排入海洋的变化做出自信的推断。这项拟议的研究将通过将先进的计算模型和大量不同的古数据集进行统计上的稳健整合，极大地完善这些推断。这将解决或进一步澄清失踪的冰层问题。该研究计划还将应用细化的冰川年表来直接检查冰川和气候系统的可变性，模型将比较气候、冰盖和地球成分。通过在这个框架内部署越来越复杂的模型，我们将测试当前的模型和理解在多大程度上能够复制和解释过去的冰盖演化和不稳定事件。这些测试反过来将促进对未来冰盖演化和相关冰盖与气候系统相互作用的不确定性的估计，填补当前气候变化评估中的一个主要缺口。

The past is our fuzzy window to the future. Through this window, tantalizing discrepancies point to cracksin our understanding of the coupled ice, earth, and climate system. The last 130,000 year history of ice andclimate change offers major changes in the state of the climate system as well as examples of abrupt tippingpoint behaviour.The dynamical source of the variability of this system is still poorly understood. There are also perplexingshortfalls in explaining inferred global mean sea level at Last Glacial Maximum (the problem of “missingice”) as well the source of an inferred 6-10 m higher sea level during the last (Eemian) interglacial, about125,000 years ago.Scientific assessments of potential climate change rely heavily on climate models. Though replication ofpresent-day climate is a challenging test for models, it is only a limited test since these models are alreadytuned to fit the present. To answer questions related to potentially large changes in the climate system(especially so-called tipping points), models are best tested against the past.Critical to these tests is a confident inference of the past change in topography, ice cover, and associatedmeltwater drainage into the ocean. The proposed research will significantly refine these inferences throughstatistically robust integration of advanced computed models and large diverse sets of paleo data. Thiswill either resolve or further clarify the missing ice issue. The research program will also apply theserefined ice chronologies to direct examination of variability in the glacial ice and climate system with modelsencompassing the climate, ice sheet, and earth components.By deploying increasingly sophisticated models within this framework, we will test the extent to whichcurrent models and understanding can replicate and explain past ice sheet evolution and instability events.These tests will in turn facilitate the estimation of uncertainties concerning both future ice sheet evolutionand associated ice sheet interactions with the climate system, addressing a major gap in current climatechange assessments.