Holocene changes in atmospheric circulation patterns as shown by lake status changes in northern Europe

Changes in lake status, a measure of relative water depth or lake level, have been reconstructed from geological and biological evidence for 87 sites in northern Europe. During the early Holocene. the lakes show conditions similar to or drier than present in a broad band across southern Britain, southern Scandinavia and into the eastern Baltic and wetter conditions along the west coast and in central Europe. This pattern is consistent with the effects of a glacial anticyclone over the Scandinavian Ice Sheet, namely enhanced southwesterly flow along the west coast and strengthened easterlies south of the ice. After c, 8000 BP a different lake status pattern was established. with conditions drier than present over much of northern Europe. Lakes higher than today were confined to the far north, the west coast, eastern Finland and western Russia. This pattern gradually attenuated after 4000 BP. Differences in lake status during the mid- to late Holocene are consistent with a strengthening of the blocking anticyclone over the Baltic Sea in summer. resulting in more meridional circulation than today. This strengthening of the blocking anticyclone during the mid-Holocene is interpreted as a consequence of insolation changes, enhanced by the fact that the Baltic Sea was larger than present.

Beyond the Threshold: Life in the New Russia

Amanda Sprang spent nine months, from September of 1995 to May of 1996, studying at Colby College's program in St. Petersburg, Russia. Through contacts made during previous trips to Russia in middle and high school, Amanda was able to quickly rekindle her old friendships and make new ones with many young Russians from different backgrounds. The following work is a collection of twelve essays about life in the New Russia. The essays are framed by a foreword and an epilogue that help place the entire work in a historical context. Although the theme of each essay emerges from a particular incident, within every story Amanda has addressed numerous topics relating to Russian life in today’s changing society. Her first essay, “Art Klinika," takes place in an avant-garde night club in St. Petersburg, and includes a brief yet impressionable, encounter with three young Russian men. “The Birthday Party” recalls a wild evening at the home of her close friend, showing how the Russians greet special occasions. Both the third and fourth essays take place in Moscow, where Amanda returns to visit old friends. These two essays portray the lives of the new economic elite in comparison with the average citizen, as well as show how young Russians face the new challenges that greet them. "Politics Russian Style" recalls a political rally in St. Petersburg, and attempts to shed light on the wacky political world of an infant democracy. Chapters Six through Ten take place away from the western cities of St. Petersburg and Moscow, as Amanda brings us to the cold, mysterious land of Siberia in the dead of winter. She recounts her five day train ride with a retired, high-powered, Communist party official, her experiences in the provincial city of Irkutsk, and a brief trip to a Buddhist monastery and, later, an excursion to Lake Baikal. Back in St. Petersburg, Chapter Eleven gives a humorous account of a ski trip with several Russian friends. Amanda finishes her work with her final chapter, “The Dacha," which describes a weekend spent at a Russian country home with her friend's family.

Social Work in Republic of Buryatia/Russia

The Republic of Buryatia is situated in Eastern Sibiria, the eastern coast of Baikal Lake. The total area of the republic is 351 thousand square kilometers. The capital of Republic is Ulan-Ude. The modern social-economic situation in Russia is extremely paradoxical and multiaspectual - negative processes take place almost in all spheres of the society. The introduction of market economy principles, the process of privatisation, and the last economic crises in the Federation of Russia have brought many social phenomena - among them increasing poverty, homelessness and still high rate of unemployment are the worst one. It makes the changes in the state social welfare programmes and functioning patterns be implemented. Social problems are especially very important in the so-called "depressive" regions of Russia (Buryatia Republic is among those regions). The most important is the staff supplement of social services and the level of professionalism of people who work there. This problem consists of two aspects: first, the number of specialists with professional education of social workers is not enough; second, the level of professionalism of the workers is very low.

Amplified bioproductivity during Transition IV (332 000-342 000 yr ago): evidence from the geochemical record of Lake El'gygytgyn

Abstract. To date, terrestrial archives of long-term climatic change within the Arctic have widely been restricted to ice cores from Greenland and, more recently, sediments from Lake El’gygytgyn in northeast Arctic Russia. Sediments from this lake contain a paleoclimate record of glacialinterglacial cycles during the last three million years. Lowresolution studies at this lake have suggested that changes observed during Transition IV (the transition from marine isotope stage (MIS) 10 to MIS 9) are of greater amplitude than any observed since. In this study, geochemical parameters are used to infer past climatic conditions thus providing the first high-resolution analyses of Transition IV from a terrestrial Arctic setting. These results demonstrate that a significant shift in climate was subsequently followed by a rapid increase in biogenic silica (BSi) production. Following this sharp increase, bioproductivity remained high, but variable, for over a thousand years. This study reveals differences in the timing and magnitude of change within the ratio of silica to titanium (Si/Ti) and BSi records that would not be apparent in lower resolution studies. This has significant implications for the increasingly common use of Si/Ti data as an alternative to traditional BSi measurements.

Climatic variability during the last interglacial inferred from geochemical proxies in the Lake El'gygytgyn sediment record

The Last Interglacial Period (LIP) is often regarded as a good analogue for potential climatic conditions under predicted global warming scenarios. Despite this, there is still debate over the nature, duration and frequency of climatic changes during this period. One particularly contentious issue has been the apparent evidence of climatic instability identified in many marine cores but seemingly lacking from many terrestrial archives, especially within the Arctic, a key region for global climate change research. In this paper, geochemical records from Lake El'gygytgyn, north-eastern Russia, are used to infer past climatic changes during the LIP from within the high Arctic. With a sampling resolution of ~20–~90 years, these records offer the potential for detailed, high-resolution palaeoclimate reconstruction. This study shows that the LIP commenced in central Chukotka ~129 thousand years ago (ka), with the warmest climatic conditions occurring between ~128 and 127 ka before being interrupted by a short-lived cold reversal. Mild climatic conditions then persisted until ~122 ka when a marked reduction in the sedimentation rate suggests a decrease in precipitation. A further climatic deterioration at ~118 ka marks the return to glacial conditions. This study highlights the value of incorporating several geochemical proxies when inferring past climatic conditions, thus providing the potential to identify signals related to environmental change within the catchment. We also demonstrate the importance of considering how changes in sedimentation rate influence proxy records, in order to develop robust palaeoenvironmental reconstructions.

A chrysophyte-based quantitative reconstruction of winter severity from varved lake sediments in NE Poland during the past millennium and its relationship to natural climate variability

Chrysophyte cysts are recognized as powerful proxies of cold-season temperatures. In this paper we use the relationship between chrysophyte assemblages and the number of days below 4 °C (DB4 °C) in the epilimnion of a lake in northern Poland to develop a transfer function and to reconstruct winter severity in Poland for the last millennium. DB4 °C is a climate variable related to the length of the winter. Multivariate ordination techniques were used to study the distribution of chrysophytes from sediment traps of 37 low-land lakes distributed along a variety of environmental and climatic gradients in northern Poland. Of all the environmental variables measured, stepwise variable selection and individual Redundancy analyses (RDA) identified DB4 °C as the most important variable for chrysophytes, explaining a portion of variance independent of variables related to water chemistry (conductivity, chlorides, K, sulfates), which were also important. A quantitative transfer function was created to estimate DB4 °C from sedimentary assemblages using partial least square regression (PLS). The two-component model (PLS-2) had a coefficient of determination of View the MathML sourceRcross2 = 0.58, with root mean squared error of prediction (RMSEP, based on leave-one-out) of 3.41 days. The resulting transfer function was applied to an annually-varved sediment core from Lake Żabińskie, providing a new sub-decadal quantitative reconstruction of DB4 °C with high chronological accuracy for the period AD 1000–2010. During Medieval Times (AD 1180–1440) winters were generally shorter (warmer) except for a decade with very long and severe winters around AD 1260–1270 (following the AD 1258 volcanic eruption). The 16th and 17th centuries and the beginning of the 19th century experienced very long severe winters. Comparison with other European cold-season reconstructions and atmospheric indices for this region indicates that large parts of the winter variability (reconstructed DB4 °C) is due to the interplay between the oscillations of the zonal flow controlled by the North Atlantic Oscillation (NAO) and the influence of continental anticyclonic systems (Siberian High, East Atlantic/Western Russia pattern). Differences with other European records are attributed to geographic climatological differences between Poland and Western Europe (Low Countries, Alps). Striking correspondence between the combined volcanic and solar forcing and the DB4 °C reconstruction prior to the 20th century suggests that winter climate in Poland responds mostly to natural forced variability (volcanic and solar) and the influence of unforced variability is low.

Pollen records and age determinations from 2 profiles at Lake Nikolay, Lena Delta

Radiocarbon-dated pollen, rhizopod, chironomid and total organic carbon (TOC) records from Nikolay Lake (73°20'N, 124°12'E) and a pollen record from a nearby peat sequence are used for a detailed environmental reconstruction of the Holocene in the Lena Delta area. Shrubby Alnus fruticosa and Betula exilis tundra existed during 10,300-4800 cal. yr BP and gradually disappeared after that time. Climate reconstructions based on the pollen and chironomid records suggest that the climate during ca. 10,300-9200 cal. yr BP was up to 2-3 °C warmer than the present day. Pollen-based reconstructions show that the climate was relatively warm during 9200-6000 cal. yr BP and rather unstable between ca. 5800-3700 cal. yr BP. Both the qualitative interpretation of pollen data and the results of quantitative reconstruction indicate that climate and vegetation became similar to modern-day conditions after ca. 3600 cal. yr BP. The chironomid-based temperature reconstruction suggests a relatively warm period between ca. 2300 and 1400 cal. yr BP, which corresponds to the slightly warmer climate conditions reconstructed from the pollen. Modern chironomid and rhizopod assemblages were established after ca. 1400 cal. yr BP.

Description of sampling sites in Northern Russia

The youngest ice marginal zone between the White Sea and the Ural mountains is the W-E trending belt of moraines called the Varsh-Indiga-Markhida-Harbei-Halmer-Sopkay, here called the Markhida line. Glacial elements show that it was deposited by the Kara Ice Sheet, and in the west, by the Barents Ice Sheet. The Markhida moraine overlies Eemian marine sediments, and is therefore of Weichselian age. Distal to the moraine are Eemian marine sediments and three Palaeolithic sites with many C-14 dates in the range 16-37 ka not covered by till, proving that it represents the maximum ice sheet extension during the Weichselian. The Late Weichselian ice limit of M. G. Grosswald is about 400 km (near the Urals more than 700 km) too far south. Shorelines of ice dammed Lake Komi, probably dammed by the ice sheet ending at the Markhida line, predate 37 ka. We conclude that the Markhida line is of Middle/Early Weichselian age, implying that no ice sheet reached this part of Northern Russia during the Late Weichselian. This age is supported by a series of C-14 and OSL dates inside the Markhida line all of >45 ka. Two moraine loops protrude south of the Markhida line; the Laya-Adzva and Rogavaya moraines. These moraines are covered by Lake Komi sediments, and many C-14 dates on mammoth bones inside the moraines are 26-37 ka. The morphology indicates that the moraines are of Weichselian age, but a Saalian age cannot be excluded. No post-glacial emerged marine shorelines are found along the Barents Sea coast north of the Markhida line.

Age determination of sediment from Lake Komi

Beach and shoreface sediments deposited in the more than 800-km long ice-dammed Lake Komi in northern European Russia have been investigated and dated. The lake flooded the lowland areas between the Barents-Kara Ice Sheet in the north and the continental drainage divide in the south. Shoreline facies have been dated by 18 optical stimulated luminescence (OSL) dates, most of which are closely grouped in the range 80-100 ka, with a mean of 88 +/- 3 ka. This implies that that the Barents-Kara Ice Sheet had its Late Pleistocene maximum extension during the Early Weichselian, probably in the cold interval (Rederstall) between the Brørup and Odderade interstadials of western Europe, correlated with marine isotope stage 5b. This is in strong contrast to the Scandinavian and North American ice sheets, which had their maxima in isotope stage 2, about 20 ka. Field and air photo interpretations suggest that Lake Komi was dammed by the ice advance, which formed the Harbei-Harmon-Sopkay Moraines. These has earlier been correlated with the Markhida moraine across the Pechora River Valley and its western extension. However, OSL dates on fluvial sediments below the Markhida moraine have yielded ages as young as 60 ka. This suggests that the Russian mainland was inundated by two major ice sheet advances from the Barents-Kara seas after the last interglacial: one during the Early Weichselian (about 90 ka) that dammed Lake Komi and one during the Middle Weichselian (about 60 ka). Normal fluvial drainage prevailed during the Late Weichselian, when the ice front was located offshore.

Pollen record and age determinations on four sites from Taymyr Peninsula, Russia

Pollen data from a Levinson-Lessing Lake sediment core (74°28'N, 98°38'E) and Cape Sabler, Taymyr Lake permafrost sequences (74°33'N, 100°32'E) reveal substantial environmental changes on the northern Taymyr Peninsula during the last c. 32 000 14C years. The continuous records confirm that a scarce steppe-like vegetation with Poaceae, Artemisia and Cyperaceae dominated c. 32 000-10 300 14C yr BP, while tundra-like vegetation with Oxyria, Ranunculaceae and Caryophyllaceae grew in wetter areas. The coldest interval occurred c. 18 000 yr BP. Lateglacial pollen data show several warming events followed by a climate deterioration c. 10 500 14C yr BP, which may correspond with the Younger Dryas. The Late Pleistocene/Holocene transition, c. 10 300-10 000 14C yr BP, is characterized by a change from the herb-dominated vegetation to shrubby tundra with Betula sect. Nanae and Salix. Alnus fruticosa arrived locally c. 9000-8500 14C yr BP and disappeared c. 4000-3500 14C yr BP. Communities of Betula sect. Nanae, broadly distributed at c. 10 000-3500 14C yr BP, almost disappeared when vegetation became similar to the modern herb tundra after 3500-3000 14C yr BP. Quantitative climate reconstructions show Last Glacial Maximum summer temperature about 4°C below the present and Preboreal (c. 10 000 14C yr BP) temperature 2-4°C above the present. Maximum summer temperature occurred between 10 000 and 5500 14C yr BP; later summers were similar to present or slightly warmer.

Pollen record of sediment profile NERO from Russia

(of book) Problems of origin of the hydrosphere, history of formation and development of underground water, of the World Ocean, lakes, rivers, surface and subsurface ice are under consideration in the book. An attempt of the complete reconstruction of the continental hydrosphere in the Eastern Europe in Late Pleistocene is made. Methods of paleohydrologic studies are described. Some papers are devoted to paleoclimatic problems of river runoff formation and paleotermic evolution of continental glaciers.