Rapid waxing and waning of Beringian ice sheet reconcile glacial climate records from around North Pacific

Abstract

Abstract. Throughout the Pleistocene the Earth has experienced pronounced glacial-interglacial cycles, which have been debated for decades. One concept widely held is that during most glacials only the Laurentide-Eurasian ice sheets across North America and Northwest Eurasia became expansive, while Northeast Siberia-Beringia remained ice-sheet-free. However, the recognition of glacial landforms and deposits on Northeast Siberia-Beringia and off the Siberian continental shelf is beginning to call into question this paradigm. Here, we combine climate and ice sheet modelling with well-dated paleoclimate records from the mid-to-high latitude North Pacific to demonstrate the episodic occurrences of an ice sheet across Northeast Siberia-Beringia. Our simulations first show that the paleoclimate records are irreconcilable with the established paradigm of Laurentide-Eurasia-only ice sheets, and then reveal that a Beringian ice sheet over Northeast Siberia-Beringia causes feedbacks between atmosphere and ocean, the result of which better explains these climate records from around the North Pacific during the past four glacial-interglacial cycles. Our simulations propose an alternative scenario for NH ice sheet evolution, which involves the rapid waxing and waning of the Beringian ice sheet alongside the growth of the Laurentide-Eurasian ice sheets. The new scenario settles the long-standing discrepancies between the direct glacial evidence and the climate evolution from around the mid-to-high latitude North Pacific. It depicts a high complexity in glacial climates and has important implications for our understanding of the dispersal of prehistoric humans through Beringia into North America.