Testing of climate simulations for the highlands of Lesotho (southern Africa) during the Last Glacial Maximum with proxy-data from phylogeography, geomorphology and palaeobiological isotope geochemistry

莱索托的高地是半干旱的南部非洲最重要的“水塔”。气候变化对水资源的影响是有争议的。在气候模型中，气温相对较小的升高会导致降水量显着减少。有趣的是，对末次冰川盛期(LGM)的气候模拟也暗示了干燥的气候，但温度明显低于今天。这一结论部分来自推测的小范围高地冰川作用，部分来自湖泊沉积物和洞穴档案，它们位于南非，由于不同的造山和水文环境，很难与莱索托联系起来。除某些文化层外，尚无冰川大冰期的沉积档案，假想的(冰缘)地貌也尚未确定年代。在Sehonghong庇护所进行的考古发掘显示，LGM层中含有鱼类遗骸，这提供了初步证据，表明至少某些高地河流肯定是活跃的。这里要检验的主要假设是，莱索托高地的大冰期气候比通常认为的要少得多。自己的数据表明，这种范式变化很可能适用于卡拉哈里地区，那里的南北半球气候拉锯变得明显。因此，推测莱索托高地的冰川没有延长(甚至没有)，是因为气候太热，而不是因为太干。对高地河流蜗牛进行的系统地理研究将能够显示蜗牛在末次盛冰期是否生活在那里，因此河流系统是否在大范围内水文活动。地貌研究将侧重于建议的(冰川周围)地貌，并将考虑其他解释。来自LGM养殖层的鱼骨的稳定同位素分析将与现代鱼类的相应数据进行比较，并将进行温差测试。

The highlands of Lesotho represent the most important “water tower” of the largely semi-arid southern Africa. The impact of climate change on water resources is discussed controversially. In climate models a relatively small increase in temperature leads to a significant decrease in precipitation. Interestingly, climate simulations of the Last Glacial Maximum (LGM) hint at dry climate as well but under notably lower temperatures than today. This conclusion is partly derived from presumedly small-scale glaciation of the highlands and partly from lake sediment and speleothem archives, which are located in South Africa and are difficult to relate with Lesotho because of different oro- and hydrographic settings. Except for certain cultural layers, there are no sedimentary archives of LGM age and supposed (peri-) glacial landforms have not yet been dated. Archaeological excavations at the Sehonghong Shelter exhibited LGM-layers which contained fish remains, providing initial evidence that at least certain rivers of the highlands must have been active. The main hypothesis which shall be tested here is that the LGM-climate of the highlands of Lesotho was significantly less dry and less cold than generally assumed. Own data suggest that such a paradigm change likely applies to the Kalahari where a northern-southern-hemisphere climate seesaw becomes apparent. The presumption thus is that the glaciers in the Lesotho highlands were not extended (or even absent) because the climate was too warm and not because it was too dry. A phylogeographic study of riverine snails of the highlands will allow to show whether the snails lived there during the LGM and consequently the river systems were hydrologically active at a large scale. Geomorphological research will focus on suggested (peri-) glacial landforms and alternative interpretations will be considered. Stable isotope analyses of fish bones from LGM-cultural-layers will be compared with corresponding data from modern fish and temperature differences will be tested.