Asian monsoon weather and climate and lake system changes on the Yunnan Plateau during the Late Holocene inferred from sclerochronological isotope patterns of gastropod shells and sediments from Xingyun and Fuxian lakes (Yunnan, China).

中国西南的云南高原是研究亚洲季风与ENSO相互作用的关键区域。它代表了青藏高原的东南延伸，自全新世早期以来一直是受极端气候影响的文化景观。到目前为止，严重干旱（如2010-2011年期间随之而来的灾难性洪水）是不可预测的，因此表明了了解极端气候变率的特征和潜在机制的重要性。我们认为，建立一个新的亚月分辨率古天气档案有助于推断季风季节的开始，雨季的降水量和长度，或季风失败，以重建近6 ka可能的周期；在此基础上，我们可以预测未来极端气候的概率。我们确定了星云湖晚第四纪沉积物中极其丰富的湖相腹足动物玛格丽亚的壳，以记录水文气象信号，这些信号可以通过稳定同位素分析进行年代学研究，每周分辨率至少为三年。在星云湖的初步调查表明，玛格丽亚贝壳可以通过湖泊沉积物取心获得，平均分辨率为百年。这意味着，在过去6 ka的每一个世纪中，大约3年的古天气信号被存档，可用于分析极端气候和推断全新世中晚期的季节性变化。通过与其他指标的比较和相关性，可以概述极端气候对文化发展的影响。

The Yunnan Plateau, in south-western China, is considered a key region for studying the interactions of the Asian monsoons with ENSO. It represents the south-eastern extension of the Tibetan Plateau and has been a cultural landscape exposed to climate extremes since the early Holocene. Severe droughts, such as during 2010-2011 which was followed by catastrophic floods, are unpredictable so far and thus demonstrate the importance of understanding characteristics and underlying mechanisms of climate extremes´ variability. We believe that establishing a new palaeo-weather archive of sub-monthly resolution may help to infer monsoon season onset, precipitation amount and length of the rainy season, or monsoon failure, in order to reconstruct possible cyclicities during the last ca. 6 ka; and based upon this we may be able to predict probabilities of future climate extremes. We have identified the shells of the lacustrine gastropod Margarya, which is extremely abundant in late Quaternary sediments of Xingyun Lake, to archive hydro-meteorological signals, that can be sclerochronologically explored by stable isotope analyses, in weekly resolution over ontogenies of at least three years. Preliminary investigations at Xingyun Lake have shown that Margarya shells can be retrieved by lake sediment coring in centennial resolution, in average. This means that for every century of the last 6 ka palaeo-weather signals of ca. 3 years are archived which can be used to analyze climate extremes and to infer Mid and Late Holocene seasonality changes. In comparison and correlation with other proxies the impact of climate extremes on the cultural development can be outlined.