Diatom record of the late Holocene in the Okhotsk Sea

The environmental conditions during the past 7000 cal yr BP in the Okhotsk Sea can be subdivided into three intervals based on diatom assemblages: (1) 6600–4650 cal yr BP open-ocean sea-ice free conditions alternated with sea-ice cover, (2) 4650–1300 cal yr BP open-ocean conditions and sea-ice cover declined, fluctuating with short duration, and cold open-ocean conditions gradually developed, and (3) 1300 cal yr BP–Present when cold open-ocean conditions predominated with occasional and rapid warming. Chronological comparisons between climatic fluctuations and cultural history in Hokkaido and Okhotsk suggest that deteriorating climate could have affected local culture.