Environmental conditions on the Tibetan Plateau (TP) during the last glacial maximum (LGM) are poorly known. Existing studies of environmental proxies and climate model simulations are contradictory, with interpretations varying between cold-dry and cold-wet environmental conditions which differentially influenced lake volumes, loess deposition and vegetation communities across the TP. Genetic and archaeological studies suggest anatomically modern paleolithic foragers initially occupied the TP between 60 and 30 ka, and may have seasonally occupied the TP during the LGM. Hence, a better understanding for LGM environmental conditions is needed in order to estimate whether paleolithic foragers could have survived on the TP during the extreme LGM cold stage. Here we report the investigation of lacustrine sediments and beach deposits within two paleoshorelines around Dagze Co on the southern TP, ∼22 and ∼42 m higher than the present lake level. Optical age estimates suggest the sediments were deposited during the LGM and mid-Holocene, respectively. TraCE-21 climate model simulation results suggest that net annual LGM precipitation in the Dagze Co basin was lower than the mid-Holocene, but about the same as that of the past 1,000 years. Combining the optical age estimates with TraCE-21 and CAM4 climate model simulation results, we deduce that increased summer precipitation and glacier meltwater supply, combined with decreased lake surface evaporation, produced LGM lake levels ∼22 m higher than present. We also synthesized paleoenvironmental records reported across the TP spanning the LGM. This synthesis suggests that the LGM climate in the northern TP was cold and dry, but that some of the southern TP was cold and wet. These relatively wetter LGM conditions in the southern TP may have favored the growth of cold-resistant plants which, in turn, may have supported larger herbivore populations, and provided food for paleolithic foragers. We conclude that seasonal or short-term human occupation of the TP during the LGM was thus more likely in the southern TP than in the north.

末次冰川期（LGM）期间青藏高原（TP）的环境条件知之甚少。现有的环境代理研究和气候模型模拟是矛盾的，在干冷和冷湿环境条件之间的解释各不相同，这对TP上的湖泊量，黄土沉积和植被群落有不同的影响。遗传和考古研究表明，解剖学上现代的旧石器时代的觅食者最初占据了TP的60至30 ka，并且在LGM时期可能季节性占据了TP。因此，需要对LGM环境条件有一个更好的了解，以便估计在极端LGM寒冷阶段是否可以在TP上幸存古石质觅食者。在这里，我们报告了对TP南部Dagze Co周围两条古海岸线内湖相沉积物和海滩沉积物的调查，比目前的湖面水位分别高出约22和约42 m。光学年龄估计表明，沉积物分别在LGM和全新世中期沉积。TraCE-21气候模型模拟结果表明，Dagze Co盆地的LGM年净降水量低于全新世中期，但与过去1000年大致相同。将光学年龄估计与TraCE-21和CAM4气候模式模拟结果相结合，我们推断出夏季降水增加和冰川融水供应增加，加上湖面蒸发减少，导致LGM湖水位比目前高出约22 m。我们还合成了跨LGM的整个TP报告的古环境记录。综合表明，北部TP的LGM气候寒冷而干燥，而南部TP的部分气候又寒冷又潮湿。TP南部这些相对较湿的LGM条件可能有利于抗寒植物的生长，这些植物反过来又可以支撑更大的草食动物种群，并为古石器时代的觅食者提供食物。我们得出的结论是，在LGM期间，季节性或短期人类对TP的占领在南部TP高于北部。