Abstract The termination of the Last Ice Age after the Last Glacial maximum (LGM) represents a dynamic period in the history of the circum-north Atlantic region. So far, there are few reliably dated climatic reconstructions covering the Lateglacial period prior to 14,700 cal. BP in Central and Northern Europe. We present a new chironomid record for the period 18,000–14,000 cal. BP, from Burgaschisee, Switzerland. Chironomid assemblages immediately following glacier retreat were dominated by taxa indicative of cold, oligotrophic conditions such as Sergentia coracina -type and Micropsectra radialis -type. A gradual transition to assemblages with moderate abundances of taxa indicative of warmer climatic conditions such as Dicrotendipes nevosus -type and Tanytarsus glabrescens -type started after ca. 16,100 cal. BP. This initial and gradual chironomid assemblage shift culminated in a more pronounced and rapid inferred temperature change at the Oldest Dryas/Bolling transition at ca. 14,700 cal. BP, where further types indicative of warm conditions such as Tanytarsus lactescens -type first occurred and replaced chironomids indicative of colder conditions such as Paracladius and Protanypus. We estimated past July air temperature changes from the chironomid assemblages by applying to the record a chironomid-temperature transfer function that is based on chironomid distribution data from 274 lakes in Switzerland and Norway. The resulting reconstruction, which features a sample-specific root mean square error of prediction of 1.36–1.46 °C, indicates temperatures around 9 °C at the beginning of the record. An initial gradual warming phase initiating at ca. 16,100 cal. BP is recorded reaching values around 10 °C for the period 16,100–15,500 cal. BP. Temperatures continue to increase reaching values around 12 °C for the period preceding the Bolling warming, when temperatures rose rapidly to values around 15 °C. The early temperature rise to values of 10–12 °C prior to the Bolling warming agrees with widespread vegetation changes recently reported for this region based on palaeobotanical analyses, which indicate a shift from herbaceous tundra to shrub tundra with low density tree birch stands with open canopies. Together, these results suggest an earlier Lateglacial temperature increase in southwest Central Europe than expected based on earlier palaeobotanical reconstructions, although with a less pronounced warming than has been reported for ca. 16,000 cal. BP from south of the Alps. This early Lateglacial warming agrees with glacier reconstructions which suggest several step-wise reductions of glacier extent in this period as well as with evidence from other palaeotemperature reconstructions and suggests that not only Southern Europe but significant parts of Europe north of the Alps may have been characterized by early Lateglacial warming well before the rapid warming at ca. 14,700 cal. BP.

中文翻译：

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夏季温度发展 18,000–14,000 卡路里。BP 被瑞士高原 Burgäschisee 的新摇蚊记录记录

摘要 末次冰期最大值（LGM）后末次冰期的结束代表了环北大西洋地区历史上的一个动态时期。到目前为止，几乎没有可靠的气候重建涵盖 14,700 卡路里之前的晚冰期。BP 在中欧和北欧。我们提出了 18,000-14,000 卡路里的新摇蚊记录。BP，来自瑞士布尔加奇湖。紧随冰川退缩后的摇蚊组合以指示寒冷、贫营养条件的类群为主，例如 Sergentia coracina 型和 Micropsectraradialis 型。逐渐过渡到具有中等丰度类群的组合，表明气候条件较暖和，例如 Dicrotendipes nevosus 型和 Tanytarsus glabrescens 型在大约 10 年后开始。16,100 卡路里 BP。这种初始和逐渐的摇蚊组合转变在大约 20 年的最古老的仙女木/博林转变处以更明显和更快速的推断温度变化而告终。14,700 卡路里 BP，首先出现了表明温暖条件的其他类型，如 Tanytarsus lactescens 型，并取代了表明较冷条件的摇蚊，如 Paracladius 和 Protanypus。我们通过将基于瑞士和挪威 274 个湖泊的摇蚊分布数据的摇蚊-温度传递函数应用到记录中，估计了过去 7 月来自摇蚊组合的气温变化。由此产生的重建具有 1.36–1.46 °C 的特定样本预测均方根误差，表明记录开始时的温度约为 9 °C。在大约开始的初始逐渐变暖阶段。16、100 卡路里 记录的血压值在 16,100-15,500 卡路里期间达到 10 °C 左右。BP。在博林变暖之前的时期，温度继续升高，达到 12°C 左右的值，当时温度迅速上升到 15°C 左右的值。在 Bolling 变暖之前早期温度上升到 10-12°C 的值与最近根据古植物学分析报告的该地区广泛的植被变化一致，这表明从草本苔原向灌木苔原转变，低密度桦木林地开放檐篷。总之，这些结果表明，中欧西南部的晚冰期温度升高比基于早期古植物重建的预期要早，尽管与大约 10 月的报道相比，变暖不那么明显。16,000 卡路里 来自阿尔卑斯山南部的BP。这种早期的晚冰期变暖与冰川重建一致，这表明该时期冰川范围出现了几次逐步减少的情况，以及来自其他古温度重建的证据，并表明不仅南欧而且欧洲阿尔卑斯山以北的重要地区都可能具有特征由早期的晚冰期变暖早于约 2000 年的快速变暖。14,700 卡路里 BP。