Download or read book 7700 Years of Holocene Climatic Variability in Sermilik Valley Southeast Greenland Inferred from Lake Sediments written by Samuel Hallett Davin and published by . This book was released on 2013 with total page 70 pages. Available in PDF, EPUB and Kindle. Book excerpt: During the latter half of the 20th century until present day there has been an unprecedented rise in global annual mean temperatures accompanied by rising sea levels and a decrease in Northern Hemisphere snow cover, which if it continues will lead to widespread disruption of climate patterns, ecosystems, and present-day landscapes. It is therefore of critical importance to establish an expanded network of paleoclimate records across the globe in order to better assesses how the global climate system has changed in the past, that we may create a metric by which to address modern change. Herein is presented a7,700 years record of Holocene climatic and environmental variability in Sermilik Valley, located on Ammassalik Island, SE Greenland. This objective of this study is to determine the timing of major Holocene climate transitions as expressed in the physical, elemental, and geochemical parameters preserved in the 484 cm sediment record of Lower Sermilik Lake. Major transitions observed in this study include the deglaciation of Sermilik Valley, the onset and termination of the Holocene Climatic Optimum, the transition into neoglacial conditions, and the Little Ice Age.
Download or read book Holocene Climate and Environmental Variability in NE Germany Inferred from Annually Laminated Lake Sediments written by Nadine Dräger and published by . This book was released on 2016 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Understanding the role of natural climate variability under the pressure of human induced changes of climate and landscapes, is crucial to improve future projections and adaption strategies. This doctoral thesis aims to reconstruct Holocene climate and environmental changes in NE Germany based on annually laminated lake sediments. The work contributes to the ICLEA project (Integrated CLimate and Landscape Evolution Analyses). ICLEA intends to compare multiple high-resolution proxy records with independent chronologies from the N central European lowlands, in order to disentangle the impact of climate change and human land use on landscape development during the Lateglacial and Holocene. In this respect, two study sites in NE Germany are investigated in this doctoral project, Lake Tiefer See and palaeolake Wukenfurche. While both sediment records are studied with a combination of high-resolution sediment microfacies and geochemical analyses (e.g. μ-XRF, carbon geochemistry and stable isotopes), detailed proxy understanding mainly focus
Download or read book Holocene Environmental Variability Inferred from Lake Sediments Southwest Yukon Territory Canada written by Joan Bunbury and published by . This book was released on 2009 with total page 362 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Variability of Holocene Climate Change written by and published by . This book was released on 1984 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Late Holocene Climate and Environmental Change Inferred from Arctic Lake Sediment written by Darrell S. Kaufman and published by . This book was released on 2009 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Holocene Paleo environmental Variability Reconstructed from a Lake Sediment Record from Southeast Greenland written by Gregory Andrew De Wet and published by . This book was released on 2013 with total page 93 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Holocene Climate Change in the Eastern United States and Canada Inferred from Lake Sedimentation Rates written by John Warren Dunham and published by . This book was released on 1986 with total page 114 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Holocene Climatic Change in the Alaskan Arctic as Inferred from Oxygen isotope and Lake sediment Analyses at Wahoo Lake written by and published by . This book was released on with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Multi proxy Study of Holocene Atmospheric Circulation Dynamics Recorded in Lake Sediments in Fennoscandia written by Natalie Ann St. Amour and published by . This book was released on 2009 with total page 253 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cellulose-inferred lake water oxygen-isotope records were obtained from five throughflow lakes situated along a north-south transect across Fennoscandia to help develop a better picture of Holocene changes in atmospheric circulation in the region. This research addresses prior evidence for the existence of non-temperature-dependent shifts in d18O of precipitation in the early Holocene attributed to changes in atmospheric circulation. The validity of this hypothesis is tested through the development of oxygen-isotope records from lake sediments and their interpretation in the context of independent reconstructions of temperature and precipitation from pollen and chironomid head-capsules collected from the same or nearby sites, and well-documented changes in vegetation composition. Records of carbon and nitrogen elemental content and isotopic composition and magnetic susceptibility are included in this multi-proxy investigation. Extensive modern isotope hydrology datasets spanning several years at four of the five sites also help to inform interpretations of the cellulose d18O records. Key results from this research are: 1) Elevated d18O in relation to prevailing temperature occurred during the early Holocene (c. 10,000-6000 cal. BP) for sites in northern Fennoscandia (Lake Tibetanus, Lake Spåime), in harmony with previous interpretations suggesting that strong zonal atmospheric circulation led to deepening of the precipitation and isotope shadows in the lee of the Scandes Mountains. 2) Evidence from a southern site (Arbovatten) reveals a previously unrecognized negative offset in the d18O-temperature relation during the early Holocene, apparently transferred directly from the North Atlantic without the orographic effects associated with a topographic barrier. 3) The modern d18O-temperature relation appears to have been established throughout Fennoscandia by c. 6000-4000 cal. BP, probably due to generally weaker circumpolar atmospheric circulation in response to lower summer insolation. 4) Comparison of two sites (Lake Spåime, Svartkälstjärn) in a west-east transect across central Fennoscandia reveals higher-frequency variability in atmospheric circulation at submillennial scales throughout the Holocene, which appears to be analogous to contemporary variability in the North Atlantic Oscillation (NAO) at seasonal-to-decadal time-scales. Evidence of such NAO-like variability also exists at two northern sites (Lake Keitjoru, Oikojärvi) during the Holocene, likely reflecting variations in summer and winter atmospheric circulation. 5) Complex lake-specific changes in productivity occurred in response to Holocene climate change, as revealed by carbon and nitrogen elemental and isotopic data in lake sediments. A major shift in atmospheric circulation pattern occurring at c. 4000 cal. BP probably led to a reduction in soil-derived 13C-depleted nutrients in five lakes (Lake Keitjoru, Oikojärvi, Lake Spåime, Svartkälstjärn, Arbovatten) associated with changes in terrestrial vegetation. Changes in sediment nitrogen isotope composition also occurred in these lakes at c. 4000 cal. BP, possibly reflecting changing nutrient supply dynamics because of enhanced nitrogen losses during spring snowmelt.
Download or read book Holocene Environmental Variability Inferred from Lake Diatoms and Sediment Geochemistry in Northeastern Siberia Russia written by Boris K. Biskaborn and published by . This book was released on 2012 with total page 140 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Holocene Climate Change from Fjord and Lake Sediment Core and Seismic Records in Southern Patagonia written by Sverre Liv LeRoy and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Lateglacial to Holocene Climatic and Environmental Changes in Europe written by Stefan Lauterbach and published by . This book was released on 2011 with total page 135 pages. Available in PDF, EPUB and Kindle. Book excerpt: Sediment records of three European lakes were investigated in order to reconstruct the regional climate development during the Lateglacial and Holocene, to investigate the response of local ecosystems to climatic fluctuations and human impact and to relate regional peculiarities of past climate development to climatic changes on a larger spatial scale. The Lake Hańcza (NE Poland) sediment record was studied with a focus on reconstructing the early Holocene climate development and identifying possible differences to Western Europe. Following the initial Holocene climatic improvement, a further climatic improvement occurred between 10 000 and 9000 cal. a BP. Apparently, relatively cold and dry climate conditions persisted in NE Poland during the first ca. 1500 years of the Holocene, most likely due to a specific regional atmospheric circulation pattern. Prevailing anticyclonic circulation linked to a high-pressure cell above the remaining Scandinavian Ice Sheet (SIS) might have blocked the eastward propagation of warm and moist Westerlies and thus attenuated the early Holocene climatic amelioration in this region until the final decay of the SIS, a pattern different from climate development in Western Europe. The Lateglacial sediment record of Lake Mondsee (Upper Austria) was investigated in order to study the regional climate development and the environmental response to rapid climatic fluctuations. While the temperature rise and environmental response at the onset of the Holocene took place quasi-synchronously, major leads and lags in proxy responses characterize the onset of the Lateglacial Interstadial. In particular, the spread of coniferous woodlands and the reduction of detrital flux lagged the initial Lateglacial warming by ca. 500-750 years. Major cooling at the onset of the Younger Dryas took place synchronously with a change in vegetation, while the increase of detrital matter flux was delayed by about 150-300 years. Complex proxy responses are also detected for short-term Lateglacial climatic fluctuations. In summary, periods of abrupt climatic changes are characterized by complex and temporally variable proxy responses, mainly controlled by ecosystem inertia and the environmental preconditions. A second study on the Lake Mondsee sediment record focused on two small-scale climate deteriorations around 8200 and 9100 cal. a BP, which have been triggered by freshwater discharges to the North Atlantic, causing a shutdown of the Atlantic meridional overturning circulation (MOC). Combining microscopic varve counting and AMS 14C dating yielded a precise duration estimate (ca. 150 years) and absolute dating of the 8.2 ka cold event, both being in good agreement with results from other palaeoclimate records. Moreover, a sudden temperature overshoot after the 8.2 ka cold event was identified, also seen in other proxy records around the North Atlantic. This was most likely caused by enhanced resumption of the MOC, which also initiated substantial shifts of oceanic and atmospheric front systems. Although there is also evidence from other proxy records for pronounced recovery of the MOC and atmospheric circulation changes after the 9.1 ka cold event, no temperature overshoot is seen in the Lake Mondsee record, indicating the complex behaviour of the global climate system. The Holocene sediment record of Lake Iseo (northern Italy) was studied to shed light on regional earthquake activity and the influence of climate variability and anthropogenic impact on catchment erosion and detrital flux into the lake. Frequent small-scale detrital layers within the sediments reflect allochthonous sediment supply by extreme surface runoff events. During the early to mid-Holocene, increased detrital flux coincides with periods of cold and wet climate conditions, thus apparently being mainly controlled by climate variability. In contrast, intervals of high detrital flux during the late Holocene partly also correlate with phases of increased human impact, reflecting the complex influences on catchment erosion processes. Five large-scale event layers within the sediments, which are composed of mass-wasting deposits and turbidites, are supposed to have been triggered by strong local earthquakes. While the uppermost of these event layers is assigned to a documented adjacent earthquake in AD 1222, the four other layers are supposed to be related to previously undocumented prehistorical earthquakes.
Download or read book Quaternary Glaciation History and Glaciology of Jakobshavn Isbrae and the Disko Bugt Region West Greenland written by Anker Weidick and published by . This book was released on 2007 with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book An Atlas of the Lakes of the Larsemann Hills Princess Elizabeth Land Antarctica written by and published by . This book was released on 1990 with total page 182 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Research and Technology Program written by and published by . This book was released on 1994 with total page 74 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Polar Lakes and Rivers written by Warwick F. Vincent and published by Oxford University Press. This book was released on 2008-09-11 with total page 363 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides an overview of the ecology of high latitude lakes, rivers and glacial environments in both the North and South polar regions. It describes each ecosystem type, the remarkable aquatic life that thrives in these extreme habitats, and the similarities and differences between Arctic and Antarctic waters.
Download or read book The Stone Age of Qeqertarsuup Tunua Disko Bugt written by Jens Fog Jensen and published by Museum Tusculanum Press. This book was released on 2009-07-27 with total page 280 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Stone Age occupations of Qeqertarsuup Tunua (Disko Bugt) are among the most thoroughly surveyed and best known in Greenland. This volume presents the results of the author's research on a regional scale as well as on the scale of a single camp site. It focuses on the horizontal dimensions rather than stratigraphies. The principal objectives are descrip-tions of settlement patterns, dwelling types and the spatial organisation of dwellings. Saqqaq and Dorset culture sites are presented and the results are synthesised and discussed in rela-tion to earlier research in the same region as well as in relation to the Palaeo-Eskimo settle-ments in other parts of Greenland.
