State and timescale-dependency of surface climate variability from the last Glacial to present day (STACY)

我提议成立一个埃米·诺特小组，调查我们星球气候的变化是否、如何以及为什么取决于它的平均温度。这一点很重要，因为温度和降水的概率分布的变化导致极端气候事件发生频率的变化，因此对社会来说比平均值变化更重要，未来气候预测是基于复杂的气候模式，因此评估其可靠性势在必行。然而，仪器记录太短，仅限于接近目前的条件下，以约束超过十年尺度的模拟变率变化。将气候模型与来自自然档案的间接古气候证据（如冰芯、洞穴沉积物或湖泊沉积物中保存的化石花粉）进行基准测试是目前唯一的解决方案。然而，模型模拟显示，在年际以外的所有时间尺度上，温度变化一般都比古气候代用数据要小得多。为了提高我们对百年气候变化的理解，我的团队将得出过去8万年气候的可靠估计。这一时期特别适合，因为它可以追溯到最后一次冰期，并涵盖了过渡到目前的温暖时期，全新世。冰消期是地球全球平均温度最后一次经历超过3°C的大规模气候变化，与未来300年的预测相当。该小组的主要目标是量化这些寒冷和温暖气候时期之间以及冰川状态内的气候变率变化，并评估气候动力学的潜在变化。这将限制建模和重建变异性之间的差距。我们将研究百年尺度总变率的变化，以及年度、百年和千年尺度气候变率之间的联系，并评估气候系统对火山爆发的敏感性是否以及如何受到季节性和全球平均温度的影响。为了实现这些目标，该小组将（a）改进洞穴沉积物和冰芯记录形成过程的现有模型，（B）利用水同位素气候模型进行创新性实验，（c）根据通过改进的过程模型连接的模型和代用数据，对过去气候进行时空重建，（d）利用新的多变量贝叶斯气候重建框架限制重建中的变化幅度。这是对从年际到千年尺度的变率的代理估计和模拟变化之间一致性的公平检验，将提高我们对气候系统长期可预测性的理解。

I propose to establish an Emmy Noether group to investigate, whether, how and why the variability of our planet's climate depends on its mean temperature. This is important because changes in the probability distribution of temperature and precipitation lead to changes in the frequency of the occurrence of extreme climatic events, and are thus more important for society than mean shifts.Future climate projections are based on complex climate models and thus the assessment of their reliability is imperative. The instrumental record is, however, too short and limited to close-to-present day conditions to constrain modelled variability changes beyond the decadal scale. Benchmarking climate models against indirect paleoclimatic evidence derived from natural archives, such as ice cores, speleothems or fossil pollen preserved in lake sediments, is the only solution for this at present. Yet model simulations display in general far less temperature variability on all timescales beyond the interannual than paleoclimate proxy data.To improve our understanding of centennial climate variability, my group will derive robust estimates of climate over the last 80,000 years. This period is particularly suitable because it extends back into the last Glacial, and covers the transition into the current warm period, the Holocene. The deglaciation was the last time Earth's global mean temperature underwent a large-scale climate shift by more than 3°C, comparable to that projected for the next 300 years.The group's main aims will be to quantify the changes of climate variability between these cold and warm climate periods, and within the Glacial state, and to assess the underlying changes in climate dynamics. This will constrain the gap between modelled and reconstructed variability. We will investigate the changes in total centennial-scale variability, as well as the linkage between annual, centennial and millennial-scale climate variability, and evaluate, if and how the sensitivity of the climate system to volcanic eruptions is influenced by seasonality and global mean temperature.To achieve these goals, the group will (a) improve current models of the formation process of speleothem and ice core records, (b) perform innovative experiments with water isotope-enabled climate models, (c) derive a spatio-temporal reconstruction of past climate based jointly on model and proxy data linked through the improved process models and (d) constrain the amplitude of change in the reconstruction using a new multivariate Bayesian climate reconstruction framework.This will allow, for the first time, a fair test of consistency between the proxy-estimated and the modelled change in variability from the interannual to the millennial scale, and will improve our understanding of the longterm predictability of the climate system.