Arctic and Boreal Climate at the Beginning of the Pleistocene

Numerous studies have indicated that northern Atlantic waters experienced a cooling trend prior to the onset of continental glaciation. The distribution and migration of boreal mollusks indicates, however, that the Arctic Ocean was unusually warm at the beginning of Pleistocene time. Apparent Atlantic cooling may have resulted from an enlargement of Bering Strait which permitted an increased flow of water from the Pacific to the Atlantic ; water was sufficiently cooled by Arctic transit to effectively lower Atlantic temperatures. Increased evaporation from a warmer and ice-free Arctic is taken as the principle initiator of continental glaciation