Summary: | The causes of last deglacial megafauna extinctions in Beringia remain highly debated, with evidence pointing to climate change, human hunting, or a combination of both. One key uncertainty is associated with the current poor understanding of regional climate evolution in part due to lack of integrated proxy-model analyses, though studies of the globe repeatedly documented large climate shifts of this time period. Here, we present terrestrial temperature and moisture reconstructions since the Last Glacial Maximum by magnetic and geochemical measurements in a sediment core collected from the northern shelf of the Bering Sea. We reconstruct the marine-terrestrial environmental teleconnections, corresponding to warmer and wetter conditions between 14,700 and 13,500 years ago associated with the Bølling/Allerød interstadial (BA). Our climate model analysis confirms proxy data and attributes the climatic amelioration to increased regional heat and moisture transport from the low-latitude North Pacific Ocean, accompanied by a northward expansion of the Westerly Jet. The increased temperature and moisture availability facilitated the expansion of shrub tundra to the expanse of the previously dominating grass and forb rangelands, which appears to lead to the disappearance of megafauna grazers during the onset of BA. Our findings emphasize a crucial role of climate-driven habitat losses in contributing to the turnover in mammal communities across the last deglacial Beringia.
|