Exploring annually laminated lake sediments for solar activity reconstructions and Sun-climate studies

太阳强迫气候变率是气候研究中最具争议的话题之一。例如，上个世纪的全球变暖是在温室气体排放增加和太阳活动高水平的背景下发生的，而1998年以来意外的温度稳定与太阳活动的减少趋势相吻合。因此，提高对太阳在气候变化中的作用的认识对于预测未来的气候发展是至关重要的。基于卫星的太阳活动记录太短，无法涵盖所有可用的太阳变化，也无法区分对气候系统的人为影响和自然影响。古气候和太阳重建可以为解决这一问题提供关键。然而，从冰芯中的宇宙形成放射性核素10Be和树木年轮中的14C得来的现有太阳强迫记录的不确定性，以及缺乏足够长的、分辨率很高的具有精确年代学的古气候时间序列，迄今为止阻碍了这类研究。因此，为了更好地理解太阳变化对气候变化的作用，有必要探索新的方法来补充现有的太阳活动记录，并在太阳强迫和气候响应之间的相对时间几乎没有不确定性的情况下研究太阳-气候联系。到目前为止，每年层压的湖泊沉积物中10Be对太阳活动重建的潜力很大程度上尚未被探索，现有的初步记录包含可以通过应用最新的分析技术来纠正的偏差。假设精选湖泊沉积物中的10Be含量反映了太阳诱导的大气生产信号。本提案的主要科学目标是：(1)探索中欧湖泊Czechowski和Tiefer See的不同沉积物记录中10Be的潜力，作为一种新的太阳活动代用物，补充现有的来自冰芯中的10Be和树木年轮中的14C的太阳活动估计，以及(2)检验太阳影响气候的假设。为了达到概述的目标，该提案将首次整合精确的日期和每年解析的10Be时间序列，这些时间序列来自不同的湖泊沉积物档案，并通过校准仪器太阳活动和气象记录以及现场监测来验证预期的太阳活动代理数据。将前所未有的太阳活动数据与来自同一湖泊的现有古气候代理数据进行比较，将使我们能够调查潜在的太阳-气候联系和相关的反馈机制，而没有时间尺度的不确定性。使用10Be和14C将Czechowski湖和Tiefer See湖的预期太阳活动和古气候记录与极地冰芯和树木年轮的记录同步，将使我们了解气候系统的领先和滞后，以及它们与全球太阳活动的可能关系。

Solar forcing of climate variability is one of the most controversially discussed topics in climate research. For example, global warming during the last century occurred in the context of increasing greenhouse gas emission and high levels of solar activity, while the unexpected temperature plateau since 1998 coincides with a decreasing trend in solar activity. Therefore, improved knowledge of the role of the Sun in climate change is essential for projecting future climate developments. The satellite-based records of solar activity are too short to cover the full range of available solar variations and distinguish anthropogenic from natural effects on the climate system. Paleoclimate and solar reconstructions can provide a key to address this problem. However, uncertainties in available solar forcing records from cosmogenic radionuclides 10Be in ice cores and 14C in tree rings and a lack of sufficiently long and well-resolved paleoclimate time-series with precise chronologies hamper such studies so far. Therefore, for better understanding the role of solar variations on climate change it is necessary to explore new ways to complement existing solar activity records and study solar-climate linkages with virtually no uncertainties in the relative timing between solar forcing and climate responses.The potential of 10Be in annually laminated (varved) lake sediments for solar activity reconstruction is, to date, largely unexplored and existing preliminary records contain biases that can be corrected for by applying the latest analytical techniques. It is hypothesized that 10Be contents in sediments from well-chosen lakes reflect the solar induced atmospheric production signal. Main scientific objectives of this proposal are to (1) explore the potential of 10Be in the varved sediment records of Central European Lakes Czechowski and Tiefer See as new type of solar activity proxy, complement existing solar activity estimates from 10Be in ice cores and 14C in tree rings, and (2) test the hypothesis of a solar influence on climate. To reach the outlined objectives this proposal will, for the first time, integrate precisely dated and up to annually resolved 10Be time-series from varved lake sediment archives and verification of the expected solar activity proxy data by calibration against instrumental solar activity and meteorological records as well as onsite monitoring. Comparison of the unprecedented solar activity data with existing paleoclimate proxy data from the same lakes will allow us to investigate potential solar-climate links and related feedback mechanisms, without time-scale uncertainties. Synchronizing the expected solar activity and paleoclimate records from Lakes Czechowski and Tiefer See to those from polar ice cores and tree rings using 10Be and 14C will provide us insights into leads and lags of the climate system and their possible relation to solar activity worldwide.