Three-century climate variations recovered from Lake Heilongtan in southwest China and potential Anthropogenic evidences

Abstract

Under increasing influences of human activities on earth surface system, the concept of Anthropocene has been proposed and widely investigated to represent such a human-dominated geological epoch. To acquire further details about the Anthropocene, investigations on high-resolution continuous records are essentially necessary, especially for regions under notable human impacts. Here, a continuous sediment record covering the past three centuries was collected from Lake Heilongtan, a closed basin lake located in the Hengduan Mountains, in southwest China. High-resolution sedimentary proxies were examined to reconstruct past climate and environment changes, including grain size distribution, geochemical element composition, and organic matter content. The results indicated that water levels were relatively higher under generally warm and wet conditions between 1717 and 1800 CE, while a decline in regional moisture after 1800 CE caused serious shrinkage of the lake level. Comparisons with regional paleoclimate records revealed that solar activity played a significant role in promoting climate variations in southwest China. After 1910 CE, the sedimentary proxies revealed an out-of-phase with regional climate changes, especially the progressive increase after 1950 CE. With the expansion of regional population, the intensified human activities have possibly affected the catchment erosion and sedimentation processes, accounting for the deviation from natural climate changes. Accordingly, the reconstructed sedimentation history in Lake Heilongtan experienced a possible transition from natural-driven to human-dominant status during the past three centuries, revealing potential evidence for the Anthropocene in southwest China.