A.A. Velichko

Climate changes in East Europe and Siberia at the Late glacial–holocene transition

Abstract The main climatic oscillations of the Lateglacial/Early Holocene (Allerod, Younger Dryas, and Preboreal) can be distinguished all over Eastern Europe and Siberia. Distribution of the main climatic indices in the Lateglacial/Early Holocene, from west to east in Northern Eurasia, shows that variations of the mean January temperature ( t Jan o ) were larger, than those of July temperature ( t July o ). As at present, t Jan o decreased to the east, while the deviations from the present-day values were greater in the west. During the Younger Dryas the seasonality of climate increased considerably, especially in the western (European) part of the studied area. The greatest negative temperature deviations from the present-day values (up to −14°C) occurred in the northwestern part of the East European Plain, near the Scandinavian ice-sheet. It can be explained by a cooling influence from the remaining large ice body. Accordingly, with degradation of the ice-sheet at the warmer intervals of the Lateglacial and Early Holocene, the regional differences in temperature deviations became smaller (up to 8°C). On the whole, precipitation ( P ) decreased in an easterly direction, though its deviations from the modern level varied for different time-intervals. During the Younger Dryas, P amounted to 60–65% of the present-day values in the East European Plain, 80% in central West Siberia, and only 50% in central Yakutia. For the entire Northern Eurasia, P did not exceed 300–350xa0mm/yr (in Yakutia it was only 100xa0mm/yr), levels typical for present-day dry steppe and semidesert zones. Nevertheless, the reconstructed changes of the main climatic indexes were proportional to the present-day climatic characteristics, so that the general tendencies of their contemporary distribution in the mid-latitudes were preserved during the entire Lateglacial/Early Holocene interval. This shows that the general circulation of the atmosphere and geographical distribution of the main Highs and Lows in the studied time-interval were in essence similar to the present-day ones. Boundaries of permafrost in Lateglacial and Early Holocene migrated in response to climate changes. The southern limit of permafrost during the Allerod was at 60°N in East Europe and 55°N in West Siberia. During the Younger Dryas it moved south to 50–52°N in East Europe, and parabolic sand dunes were formed.

The last glaciation of earth: Size and volume of ice-sheets

Abstract The volume and size of the late glacial ice-sheets in the Northern Hemisphere has been estimated, based on geomorphic and chronostratigraphic data. Limited glacial extents during the late glacial maximum characterized both Arctic Canada and northern Eurasia, in contrast to the presence of the large Laurentide, Scandinavian and Devensian ice-sheets to the south. Glacial maxima were not synchronous throughout the Northern Hemisphere: for example, the Novaya Zemlya ice-sheet reached its maximum extent ca. 39,000 BP, approximately 20,000 years earlier than the maximum extent of the contiguous Scandinavian ice-sheet. Western and central Siberia, and the Chukhui Peninsula, were marked by limited glaciation during the last glacial maximum, although pre-Sartanian events were more extensive. Mountain glaciation in northeast Asia was similarly restricted during the last glacial maximum. Spatial and dynamic characteristics of the last glaciation developed in response to climatic factors. The establishment and strength of high-pressure systems over Siberia limited precipitation and glacier formation throughout northeastern Eurasia.

Chapter 26 – Glaciations of the East European Plain: Distribution and Chronology

The quaternary chronology and distribution of glaciations through the last million years is described. The scheme of main paleogeographical events is based on multidisciplinary studies (geological, paleontological, palynological and paleopedological evidences). Succession of glaciations – Don (the maximum one), Dnieper (with Moscow Stage), and Valdai – shows a consistent reduction of ice sheets sizes and westward displacement of their centers due to climatic reasons. The extreme cooling, as well as the maximum permafrost expansion occurred at the end of the Pleistocene (MIS 2).

Development of the steppe zone in southern Russia based on the reconstruction from the loess-soil formation in the Don-Azov Region

Herbaceous communities in forest ecosystems on the southern part of the Russian Plain appeared in the Middle Miocene (∼10 Ma BP). In the Late Miocene (∼7 Ma BP), feather-grass steppe associations appeared among them. In the time span of 2.7 to 2.1 Ma BP (i.e., in the Early Quaternary, according to the current chronostratigraphic scale), the steppe zone arose on the southern Russian Plain in the Don-Azov Region. Seven stages of this zone development here have been distinguished throughout the Quaternary. The first one (Eopleistocene-Early Pleistocene) was characterized by savanna-like subtropic ecosystems. Then, in the Middle Pleistocene, the temperate zone ecosystems (tallgrass prairie-like steppes) developed here and were followed by steppe ecosystems close to the modern ones in Central Europe. The ecosystems of rich-species forb steppes developed in the Late Pleistocene. Finally, in the optimum of the modern interglacial (Holocene), steppes became similar to the modern ones here, but with a slightly higher precipitation. The general trend is characterized by reduction in heat and water provision and increase in aridization progressing from earlier to later stages.

Paleoclimatic record from Chumbur-Kosa section in Sea of Azov region since Marine Isotope Stage 11

Loess–paleosol sequences preserve records of climatic change during the Quaternary, which is important for paleoclimate study. In this study, a loess-palaeosol sequence from the Chumbur-Kosa (CK) site in the Sea of Azov region was investigated to reconstruct climatic variability during the Marine Isotope Stage (MIS)11- MIS 1, using proxies of grain size (GS), magnetic susceptibility (χlf and χfd(%)), carbonate content (CaCO3%) and soil color. The results enabled formulation of a detailed description of the climatic characteristics related to each individual layer. The sequence indicates that the paleoclimate shifted progressively towards increasingly cooler, somewhat drier conditions. The CK section may thus be ideal for reconstructing climatic conditions during the Middle and Late Pleistocene in the Sea of Azov region. However, the χlf value of paleosol S2 in the CK profile indicates different characteristics from the other paleosol layers, dilution of carbonate resulting from carbonate leaching in L2 may be the main reason for the decrease in magnetic susceptibility. Furthermore, through simple analysis part of the environmental evolution process in the Sea of Azov region and Serbia during Middle and Late Pleistocene cycles. The climate cycle expressed by χfd(%) and χlf variations show similar patterns, with rapidly alternating cold and warm intervals. Nevertheless, although the two areas had different climatic regimes, geographical settings, and loess source areas, both exhibited similar climate change trends since the MIS 11.

Paleoanalogues of Global Warming in the 21st Century

On the basis of landscape-climatic reconstructions for warming periods in the past, likely scenarios of future global warming have been developed for various warming levels that might be reached during the current century. The paleoanalogue of global warming by 0.7–1°C is the Holocene climatic optimum (5.5–6 ka B.P.) and that by 1.7–2°C is the last interglacial optimum (about 125 ka B.P.). The complex analysis concerning response of the principal ecosystem components to the expected warming signifies that there will not be any shifts of vegetation zones during the 21st century; reconstruction will touch only the internal structure of vegetable associations and broadening of interzonal ecotones.

СМЕНА ЛАНДШАФТНЫХ ОБСТАНОВОК НА ЮГЕ РУССКОЙ РАВНИНЫ В ПОЗДНЕМ ПЛЕЙСТОЦЕНЕ ПО РЕЗУЛЬТАТАМ ИССЛЕДОВАНИЯ ЛЁССОВО-ПОЧВЕННОЙ СЕРИИ ПРИАЗОВЬЯ

Based on the complex studying 10 meter thick loess-soil sequence in the Beglitsa section (47°08° N, 38°31° E), the landscape and climate changes in the north-eastern Azov Sea Region in the Late Pleistocene were reconstructed. The intensity of loess accumulation decreased in the interglacial and interstadial conditions, when the soil-forming processes prevailed, and increased in cryoarid conditions of the glacial epoch, and especially, during the Late Valdai. As indicated by topography of palaeosoil horizons, loess layers of various ages envelope in sequence the primary fluvial (erosional-accumulative) relief. Loess accumulation resulted in general rise of the terrace surface. It preserved the major features of original topography but gradually smoothed the minor ones. During the entire Late Pleistocene the studied area belonged to the steppe zone. Participation of forbs in steppe communities, as well as the grass cover density, decreased in the cryoarid periglacial conditions and increased under warmer and less continental interstadial or interglacial climate. The role of intrazonal tree communities (pine forests with steppe elements, birch and alder wet forests) remained minor even in the most favorable climate of the Mikulino Interglacial, when the broad-leaved trees (mainly Quercus) participated in the forests. During the interstadial warm phases of the Valdai glacial epoch, the trees growing at present in the severe continental climatic conditions (Larix, Pinus sibirica) occurred in the region. As in the present time, near the shore of the Azov Sea, the areas with disturbed soil cover, including those with saline soil, were widespread due to abrasion, development of slumps and landslides, and erosion.

Luminescence chronology and age model application for the upper part of the Chumbur-Kosa loess sequence in the Sea of Azov, Russia

A reliable chronology is essentially critical for correlating loess records with other paleoenvironmental time series, as well as for continuing improvements in the reconstruction of paleoenvironment and paleoclimate changes. It is exactly that the scarcity of chronologies across the Sea of Azov has limited the interpretation of climatic and environmental information in the East European Plain. In view of this, this paper conducted an exploratory study to investigate whether the optically stimulated luminescence (OSL) dating of mediumgrained quartz could be used to obtain a set of chronologies and the age models could be used to establish an independent time scale since the Late Pleistocene for the Sea of Azov loess. The results showed that an internally consistent set of optical ages for the Azov loess deposited up to ~76 ka. In addition, the ages developed based on magnetic susceptibility and grain size ages models showed good comparability with independent OSL ages at an acceptable range, suggesting that it might be practicable to establish an independent time scale using age models at the Sea of Azov loess, at least for the uppermost part of the Chumbur-Kosa section. Comparison with the ages based on two age models, the grain size ages using fine-grain fractions may provide a more reliable chronological sequence at the Azov loess since the Late Pleistocene. With the help of absolute ages and climate proxies (magnetic susceptibility and grain size), paleoclimatic change in the Sea of Azov have been traced for the Late Pleistocene.

11 – Stages of the initial human colonization of Arctic and Subarctic

Abstract Chronostratigraphic, paleogeographic, and archaeological data allow defining the main phases of the initial human settlement in High latitudes. Between 35 and 12xa0kyrxa0BP, two different directions of peopling could be reconstructed: along the basins of the Kama and Pechora Rivers in Eastern Europe, and along the Lena and Yana Rivers in Northern Asia. The Late Pleistocene saw the peopling of West Siberia and Northeastern Asia. The same time witnessed the initial peopling of the Western Hemisphere, from Chukotka to Alaska by the Bering Land Bridge. The next phase of human dispersals in High latitudes is associated with the Mesolithic and Neolithic (9–4xa0kyr BP), when humans approached the northernmost point of Greenland. The peopling of the islands in Arctic seas took place later.

PALEOGEOGRAPHICAL MAPPING: APPROACHES, METHODS, AND RESULTS

The authors describe the evolution of a new field in cartography—the substantive basis of which is the preparation of a series of spatial reconstructions (climate, landscape components) of the past on the basis of principles of comprehensive mapping of contemporary geosystems. The paper investigates how such an approach may be used to assess the present status of landscapes from the perspective of their general evolution and assist in the formulation of long-range predictions. Translated by Edward Torrey, Alexandria, VA from: Izvestiya Akademii Nauk, seriya geograficheskaya, 1998, No. 5, pp. 30-43.