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Lake sediment cores spanning the last 2000 years from four sites across the Canadian Arctic Archipelago (CAA) document the responses of terrestrial and freshwater ecosystems to regional climate variability. Biogenic silica (BSi) records in cores from Banks Island, NWT (Lake B503; 72.3245, -123.4036, 84 masl), Bathurst Island, Nunavut (PR01; 75.6497, -99.1144, 30 masl), Prince of Wales Island, Nunavut (SW08; 72.3177, -97.2678, 104 masl), and Ellesmere Island, Nunavut (CV03; 79.9211, -82.9348, 363 masl) were used to examine the relationship between diatom production and climate. A pollen record from Prince of Wales Island provided the first high-resolution July temperature reconstruction for the last 1000 years for the central CAA. Dissolution was evident in three out of the four lakes; core SW08 contained no BSi above detection and cores CV03 and PR01 only contained values above detection in the uppermost sediments, suggesting that the preservation of biogenic silica (BSi) in the sediment is likely influenced by sedimentary carbonates. A BSi sequence from core B503 showed that diatom production was affected by climate changes such as the Medieval Climate Anomaly and the Little Ice Age. The vegetation on southern Prince of Wales Island underwent marked transitions during the Little Ice Age and Medieval Climate Anomaly, which was mainly observed in the proportion of Cyperaceae and Poaceae. The mean July temperature reconstruction showed a long-term cooling from 1080-1915 CE with a sustained cold period from 1800-1915 CE prior to 20th-century warming. A synthesis of paleoclimate records from across the Arctic demonstrated that pollen-based reconstructions record both high and low frequency climate variability, when sampling resolution is sufficient, and can improve regional climate reconstructions.
Concerns about the effects of global climate change have focused attention on the vulnerability of circumpolar regions. This book offers a synthesis of the spectrum of techniques available for generating long-term environmental records from circumpolar lakes.
This is the third volume in The Oxford Regional Environments series. The series volumes are devoted to major regions of the world, each presenting a detailed and up-to-date body of scientific knowledge concerning a particular region. For most topics on the physical geography of Northern Eurasia abundant literature now exists. Most of it, however, is in Russian and other East European languages and this has significantly limited the number of potential readers. This volume seeks to familiarize, at an international level, those with an interest in this area with the most significant achievements in classical and current geographical research. The Physical Geography of Northern Eurasia covers most of the territory of the former USSR. The first section discusses the individual compenents of the physical environment. These chapters cut across regional boundaries and treate the area discussed as a whole. A regional analysis follows mainly in the context of geographical zonation, though a number of specific regions are given individual treatment. The concluding chapters discuss the effects of anthropogenic activities on the physical environment. The approach is an integrative one, tying together various aspects of the physical environments with the environmental implications of human activites. Every component of the environment is treated as a step in the development of the multi-faceted landscapes which in turn provide possibilities and limitations for cultural and economic usage.
Human demographic changes in association to environmental fluctuations were studied for the North American Arctic and boreal region. Using the frequency of archaeological radiocarbon dates from the Canadian Archaeological Radiocarbon Database as a proxy for population size, past changes in population density were estimated and quantitatively examined in relation to reconstructions of temperature and sea ice conditions. This was conducted across three spatial scales: the entire area, the four major cultural-environmental regions and sixteen subregions in order to identify both broad-scale and local phenomena. There was a high correspondence between millennial and centennial-scale climate variability and paleodemographic changes across the region, with increasing population density during warmer periods and lower density during cooling episodes. An abrupt Late Holocene cooling (neoglaciation) beginning at 3.9 ka triggered a nearly-synchronous population decline across the region. Cooling temperatures and increased sea ice coverage also influenced large-scale migration patterns of Paleo-Inuit peoples as well as their cultural evolution.
The Palliser Triangle extends from south-west Manitoba to south central Alberta, and is one of the most climatically sensitive regions in Canada. There is evidence & concern that climate change is likely to affect the Triangle. The geological record contains unique information on the impacts of a wide range of past climate changes. This paleoenvironmental record, and the context it provides for assessing the impacts of future climate change, is the focus of the Palliser Triangle Global Change Project. This bulletin contains 18 papers related to two major objectives of that Project: reconstruction of Holocene climatic and hydrological changes, and evaluation of the relationships between climate & landscape processes. The first paper is an overview of the Project and a broad synthesis of major results. The next nine papers are devoted to records of past climate & hydrological change documented in paleolimnological and hydrogeological studies. The rest of the papers focus on geomorphic processes in the Triangle and how these respond to climate forcing.
Paleoclimatic research in the Canadian Arctic has increased in recent decades; however, there is still much to learn about the nature and extent of past climate change in this vast, environmentally sensitive region. This thesis uses diatom assemblages in dated lake sediment cores as proxy indicators to infer how climate has changed over the Holocene in two very different lakes in the central Canadian Arctic: one located in a poorly-studied geographical region, and another possessing limnological characteristics that are unusual in an Arctic context. Lake TK-2 is located in the low Arctic tundra. Paleolimnological studies from this region are lacking, as most have centered on sites in the High Arctic Archipelago or around Subarctic treeline. Marked changes in the diatom assemblages in TK-2 throughout the Holocene included potential evidence for the 8.2k cooling event, which has not been previously reported from other Canadian Arctic paleolimnological studies. In addition, diatom shifts occurring ~7000 and ~3500 cal yr BP are indicative of mid-Holocene warming and subsequent Neoglacial cooling, respectively, the timings of which agree with those from other studies farther south. Finally, shifts in the diatom assemblages in the upper sediment layers, beginning in the early-to-mid 19th century, are consistent with reduced ice cover, related to recent warming. Stygge Nunatak Pond, a small, closed-basin pond located on a nunatak in the High Arctic on Ellesmere Island, is characterized by unusually high ionic concentrations for an inland Arctic pond. As in TK-2, Stygge's diatom assemblages changed substantially throughout the Holocene, but especially in the most recent sediments. Diatom shifts near ~10,500 cal yr BP suggest an early onset for the Holocene Thermal Maximum (and for the successive Neoglacial cooling trend) in this region, consistent with previous studies from the High Arctic. Marked diatom assemblage changes occurred in the most recent sediments, and are indicative of climate warming and reduced ice cover, as well as increased ionic concentration due to enhanced evaporative concentration. The dynamic nature of the diatom assemblage changes at the Stygge site suggests that sediments from these rare athalassic ponds represent an especially sensitive archive of Arctic climatic and environmental change.