ИСТИНА

On a global scale, the last interglacial period is generally regarded a time of extreme climate warmth, high sealevel and largely reduced ice sheet size, for instance, on Greenland. In order to properly interpret the climate of the last interglacial in this region, it is critical to understand its development from the Saalian glacial maximum through the ensuing deglaciation (Termination 2). For this purpose we have compared deep-sea marine records from the Nordic seas with a high-resolution sequence of Eemian marine beds directly overlying Saalian till in northern Russia. The latter record allows for a fresh, detailed evaluation of a sequence of events on the basis of changes in lithology, microfossils (foraminifers, ostracods, pollen, aquatic palynomorphs) and benthic foraminiferal stable isotope data. The record is marked by the collapse of the huge Saalian shelf-based ice sheet which left a glaciostatically overdeepened Barents-Kara Sea shelf region, giving way to a rapid marine inundation. Although the early accumulation of marine sediments features a period of harsh, fluvially-affected environmental conditions with cold turbid waters and heavy seasonal sea-ice cover, the later occurrence of a typical Arctic shelf and deep-sea microfossil assemblage together with broad-leaved species in pollen spectra is representative of a climatic amelioration that ocurred in various steps. The recognition of a stepwise nature of the environmental development in northern Russia is recorded also in the deep-sea. There we note already during early Termination II a clear signal for intrusions of Atlantic water masses on the one hand, and high discharge rates of icebergs on the other. If these icebergs derived from a rapid collapse of the Barents-Kara seas ice sheet – this was much thicker and larger than in the Weichselian – then it seems very probable that the Atlantic water masses were able to protrude far eastward along the northern Eurasian periphery as a direct consequence of former ice sheet size and shelf overdeepening.