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Permafrost Extremes - Permafrost and Periglacial Processes in the Siberian Arctic

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Schirrmeister, L. , Hubberten, H. W. , Diekmann, B. , Kienast, F. , Andreev, A. , Siegert, C. , Kuznetsova, T. , Derevyagin, A. Y. and Kunitsky, V. V. (2007): Permafrost Extremes - Permafrost and Periglacial Processes in the Siberian Arctic , First Conference on Arctic Palaeoclimate and its Extremes (APEX) Planning of International Polar Year activities and preliminary results March 28-29, 2007, Stockholm, Sweden. .
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Abstract:

During the last decades, palaeoclimatic research on the Arctic palaeo-environment has been mainly concentrated on Neogene ice-sheet dynamics, related to the multiple waxing and waning of large regional ice sheets in northern America, Scandinavia, and western Siberia. Another outstanding and neglected feature of the Arctic realm is the occurrence of persistent permafrost that developed in the widespread periglacial regions of central and eastern Siberia and parts of the American Arctic over a long time. These areas only locally were affected by restricted mountain glaciations. One of the upcoming challenges in Arctic palaeoclimatic research in the framework of the APEX topic Permafrost Extremes is to decipher the role and environmental effects of the vast permafrost regions on the northern-hemispheric climate system during the present and past.Various paleo-environmental records are stored in permafrost sequences that are exposed along Arctic coasts of Siberia and Siberian riverbanks. The Late Pleistocene-Holocene paleo-environment of the Laptev Sea Region has been well studied during the last ten years by joint German-Russian projects. However, the exact timing of climate-driven permafrost onset and dynamics during the late Cenozoic are mostly unknown yet in a regional and global context.The long-term existence of permafrost in eastern and central Siberia suggests stable climate conditions in the areas located around the Siberian high-pressure cell, since at least the mid-Pleistocene climate transition towards stronger glacial stages or even older.However, latest findings give evidence of repeated stages of ice-rich permafrost degradation and aggradation, the existence of widespread dry Arctic shelf areas during glacial periods and their flooding during interglacial times, and the presence of mountain glaciations in the Verkhoyansk Ridge that temporarily might had led to the formation of ice-dammed lakes in the Lena hinterland.The latter scenarios of environmental changes point to complex responses and feedback loops of the periglacial system, which might be driven either by global climate teleconnections or may result from internal periglacial processes. An open question still concerns the influence of short-term climate see-saw effects through fluctuating modes of atmospheric circulation, such as the North Atlantic/Arctic Oscillation, and the impact of teleconnections from the low latitudes through the monsoon.A high number of local multi proxy records from permafrost sequences and lake sediments reflect the environmental history of the period between MIS 6 to MIS 1, especially in Central Yakutia and the Laptev Sea region at various geochronological resolutions. While lake records yield a high chronological resolution of the Late Pleistocene and Holocene, the permafrost records provide a better picture of spatial climate variability and reach farther back in time (e.g. Late Saalian, Eemian).Questions:- How did changes of atmospheric and respectively oceanic circulation influence the extended permafrost areas of Siberia?- Which climate changes have been modeled yet and how do the simulated conditions correlate with paleo records from Siberia?- How did the dry arctic shelves influence the circulation patterns during glacial times (concerning e.g. albedo, vegetation cover)?- What are the relationships between glaciated and non-glaciated northern Eurasia?- Did fresh-water influxes from the Siberian mainland affect ocean circulation of the Arctic Ocean and the North Atlantic? ; And if so, what were the reasons therefore: sudden outbursts of ice-dammed rivers or prolonged melting of ice-rich permafrost?Palaeo record project ideas:- Reconstruction of Aridity/ continentality, using palaeoecological records (e.g. pollen, plant macrofossils, ostracodes, diatoms), stable isotope data (ground ice, ostracod shells) and geochemical data.- Assessment of Cyclic patterns in high-resolution lake-sediment records of Siberia- Reconstruction of moisture sources and palaeo winter temperatures by stable isotope signatures in ground ice.- Evaluation of key site records in terms of changes in vegetation, paleo hydrology/ freshwater budget

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