MIS 3 climate transitions revealed by high-resolution loess records from the eastern margin of the Tibetan Plateau

Humans evolved rapidly and significantly between 60 and 20 ka, placing unprecedented demands on detailed climate evolution during the marine isotope stage (MIS) 3 period. In this study, a high-resolution loess record from the eastern margin of the Tibetan Plateau revealed that the climate was optimal in 62-43.5 ka, relatively stable in 43.5-34 ka, and continuously cooled in 34-20 ka. Such a three-stage pattern can be well correlated with changes in the temperature and CO2 content in Antarctica, climate evolution in Europe, and advances in the Laurentide Ice Sheet. The climate transition at 43.5 ka was closely related to the declining boreal summer insolation, CO2 content, temperature, and sea level, whereas the climate transition at 34 ka corresponded to a decrease in the CO2 concentration and development of polar ice sheets. These results are of great scientific significance because they provide insights into MIS 3 climate transitions and human migration.