The Pliocene-Pleistocene boundary, set at 2.588 Ma or the base of the Gelasian age, represents a shift in global climates from those of the comparatively warm Pliocene to the cooler conditions of the Pleistocene. Lake El’gygytgyn (Chukotka) provides one of the few continuous terrestrial records that permits a close examination of this important transition in Earth’s climate states. The MIS 102-MIS 103 portion of the El’gygytgyn palynological record indicates that, during the earliest Pleistocene, this area of the Arctic was vegetated by closed Larix-BetulaAlnus forest. Such vegetation contrasts to that of the latest Pliocene, when Larix forest-tundra dominated, and differs from the herb and shrub tundra found today in northern Chukotka. This earliest period of the Gelasian represents the climatic optimum for MIS 103. Even under the most severe conditions during MIS 102, Larix forest-tundra persisted, which differs greatly from the herb tundra that characterized many glacial intervals in the Arctic during the Late and Middle Pleistocene.