The main objective of this dissertation is to improve the knowledge of glacial chronology and paleoclimate of Turkey during the Late Quaternary. The 36Cl cosmogenic exposure ages of moraines show that Last Glacial Maximum (LGM) glaciers were the most extensive ones in Turkey in the last 22 ka (ka=thousands years), and they were closely correlated with the global LGM chron (between 19±23 ka). LGM glaciers started retreating 21.3±0.9 ka (1σ) ago on Mount Erciyes, central Turkey, and 20.4±1.3 ka ago on Mount Sandiras, southwest Turkey. Glaciers readvanced and retreated by 14.6±1.2 ka ago (Late Glacial) on Mount Erciyes and 16.2±0.5 ka ago on Mount Sandiras. Large Early Holocene glaciers were active in Aladaglar, south-central Turkey, where they culminated at 10.2±0.2 ka and retreated by 8.6±0.3 ka, and on Mount Erciyes, where they retreated by 9.3±0.5 ka. The latest glacial advance took place 3.8±0.4 ka ago on Mount Erciyes. Using glacier modeling together with paleoclimate proxy data from the region, I reconstructed the paleoclimate at these four discrete times. The results show that LGM climate was 8-11oC colder than today (obtained from paleotemperature proxies) and wetter (up to 2 times) on the southwestern mountains, drier (by ~60%) on the northeastern ones and approximately the same as today in the interior regions. The intense LGM precipitation over the mountains along the northern Mediterranean coast was produced by unstable atmospheric conditions due to the anomalously steep vertical temperature gradients on the Eastern Mediterranean Sea. In contrast, drier conditions along the southern Black Sea coast were produced by the partially ceased moisture take-up from the cold or frozen Black Sea and prevailing periglacial conditions due to the cold air carried from northern hemisphere's ice sheets. Relatively warmer and moister air from the south and overlying cold and dry air pooled over the northern and interior uplands created a boundary between the wet and dry LGM climates somewhere on the Anatolian Plateau. The analysis of Late Glacial advances suggests that the climate was colder by 4.5-6.4oC based on up to 1.5 times wetter conditions. The Early Holocene was 2.1oC to 4.9oC colder on Mount Erciyes and up to 9oC colder on Aladaglar, based on twice as wet as today's conditions. The Late Holocene was 2.4-3oC colder than today and the precipitation amounts approached the modern levels. Glaciers present on Turkish mountains today are retreating at accelerating rates and historical observations of the retreat are consistent with the behavior of other glaciers around the world.

No description available.

No description available.

Holocene climate variability in the British Columbia Coast Mountains has resulted in repeated intervals of glacier expansion and retreat. Since reaching their late Holocene maximum positions in the late 20th century, glaciers in the region have experienced significant volumetric loss. The subsequent downwasting and frontal retreat has revealed forests buried by glacier advances throughout the Holocene, enabling description of significant intervals of ice expansion using dendroglaciology. This thesis characterizes dendroglaciological evidence as it relates to climate at two scales: (1) at Franklin Glacier in the Mt. Waddington area, and; (2) throughout the Coast Mountains. Dendroglaciological evidence from glacier forefields and lateral moraines in the Coast Mountains provides evidence for at least 11 intervals of glacier activity during the Holocene. The earliest record glacier activity is documented in the Pacific Ranges from 8.5 to 7.8 ka, after which glaciers in this region retreated during the early Holocene warm and dry interval. Following this a glacial advance from 6.7 to 5.6 ka was followed by a subsequent expansion episode from 5.1 to 4.6 ka in response to attendant cool and moist conditions in the Pacific Ranges. After 4.6 ka, glaciers in the Pacific and Boundary ranges advanced at 4.4 to 4.0 and 3.8 to 3.4 ka during intervals characterized wet conditions resulting from an intense, eastwardly positioned Aleutian Low pressure centre. Following 3.4 ka most glaciers retreated before expanded between 3.2 and 2.8 ka, retreated, and then advanced from 2.6 to 2.4 ka. Glacier advances from 1.8 to 1.1 ka occurred in response to a regional cooling event, and proceeded Little Ice Age advances from 0.6 to 0.4 ka. Franklin Glacier is an 18-km long valley glacier that originates below the west face of Mt. Waddington. Radiocarbon-dated wood samples from the proximal faces of lateral moraines flanking the glacier show that it expanded at least nine times since 13 ka. A probable Younger Dryas advance of Franklin Glacier at 12.8 ka followed the late glacial retreat and downwasting of the Cordilleran Ice Sheet from ca. 16.0 to 12.9 ka. During the succeeding early Holocene warm period, Franklin Glacier appears to have retreated significantly, leaving no record of glacial expansion until the mid-Holocene when it repeatedly advanced at 6.3, 5.4, and 4.6 ka in response to cool summer temperatures and generally moist conditions. Downwasting of the glacier surface after 4.6 ka was followed by intervals of expansion at 4.1, 3.1, and 2.4 ka contemporaneous with a period of increased precipitation. Following ice expansion at 2.4 ka into trees over 224 years in age, there is no record of the glacier activity until 1.5 ka when Franklin Glacier thickened and advanced into young subalpine fir trees, reflecting attendant cool and wet environmental conditions. During the Little Ice Age, advances at 0.8 and 0.6 ka preceded a mid-19th to early-20th century advance that saw Franklin Glacier attain its maximum Holocene extent in response to an extended interval of cold temperatures. The dendroglaciological record at Franklin Glacier is among the most comprehensive recovered from the British Columbia Coast Mountains and showcases the complexity of latest Pleistocene and Holocene glacier behaviour in the region. / Graduate / 0368 / bjmood@uvic.ca

The Darwin-Hatherton glacial system (DHGS) drains from the East Antarctic Ice Sheet (EAIS) and through the Transantarctic Mountains (TAM) before entering the Ross Embayment. Large ice-free areas covered in glacial sediments surround the DHGS, and at least five glacial drift sheets mark the limits of previous ice extent. The glacier belongs to a group of slow-moving EAIS outlet glaciers which are poorly understood. Despite this, an extrapolation of a glacial drift sheet boundary has been used to determine the thickness of the EAIS and the advanced West Antarctic Ice Sheet (WAIS) during the Last Glacial Maximum (LGM). In order to accurately determine the past and present contributions of the Antarctic ice sheets to sea level changes, these uncertainties should be reduced. This study aims to examine the present and LGM ice dynamics of the DHGS by combining newly acquired field measurements with a 3-D numerical ice sheet-shelf model. The fieldwork included a ground penetrating radar survey of ice thickness and surface velocity measurements by GPS. In addition, an extensive dataset of airborne radar measurements and meteorological recordings from automatic weather stations were made available. The model setup involved nesting a high-resolution (1 km) model of the DHGS within a lower resolution (20 km) all-Antarctic simulation. The nested 3-D modelling procedure enables an examination of the impact of changes of the EAIS and WAIS on the DHGS behaviour, and accounts for a complex glacier morphology and surface mass balance within the glacial system. The findings of this study illustrate the difference in ice dynamics between the Darwin and Hatherton Glaciers. The Darwin Glacier is up to 1500 m thick, partially warm-based, has high driving stresses (~150 kPa), and measured ice velocities increase from 20-30 m yr⁻¹ in the upper parts to ~180 m yr⁻¹ in the lowermost steepest regions, where modelled flow velocities peak at 330 m yr⁻¹. In comparison, the Hatherton Glacier is relatively thin (<900 m), completely cold-based, has low driving stresses (~85 kPa), and is likely to flow with velocities <10 m yr⁻¹ in most regions. It is inferred that the slow velocities with which the DHGS flows are a result of high subglacial mountains restricting ice flow from the EAIS, large regions of frozen basal conditions, low SMB and undulating bedrock topography. The model simulation of LGM ice conditions within the DHGS implies that the ice thickness of the WAIS has been significantly overestimated in previous reconstructions. Results show that the surface of the WAIS and EAIS away from the TAM would have been elevated 600-750 and 0-80 m above present-day levels, respectively, for the DHGS to reach what was inferred to represent the LGM drift sheet limit. Ultimately, this research contributes towards a better understanding of the dynamic behaviour of slow moving TAM outlet glaciers, and provides new insight into past changes of the EAIS and WAIS. This will facilitate more accurate quantifications of contributions of the WAIS and EAIS to changes in global sea level.

Snow and glaciers are considered the most important sources of the estimated 32-60% of global water resources which are provided by mountains. Consequently, snow and glaciers have regularly been the focus of climate change studies in mountain regions. Rock glaciers are a type of ice-debris landform characterized by creeping ice-rich permafrost. Recognition of the hydrological significance of rock glaciers is increasing and is of particular relevance to the Arid Andes, where rock glaciers cover greater area than glaciers by an order of magnitude. Little research exists on the hydrological significance of rock glaciers beyond potential water storage capacities and their runoff pathways. Additional knowledge and research approaches pertaining to the seasonal hydrological contributions and climatic sensitivities of rock glaciers are necessary for improved water resource planning in many regions around the world. This work explored the feasibility of utilizing the energy and water balance model GEOtop to quantify the thermal and hydrological dynamics of rock glaciers under several climate scenarios. Weather data was generated with the intermediate-stochastic weather generator AWE-GEN for a site in the Southeast Swiss Alps, which marked a novel approach in studies of rock glaciers. Weather data for a reference (REF) scenario was generated which approximates conditions during the observation period (1985 to 2012). AWE-GEN produced time series of weather data for the REF scenario with statistical properties of precipitation in close agreement with observations. Air temperature had substantial inaccuracies with mean annual air temperature (MAAT) cooler by 1.82 C due to negative temperature biases in summer months which are attributed to difficulties in estimating parameters of the weather generator model caused by local climatic factors. The influence of climate change was also examined. Data for 8 climate change scenarios were generated by specifying change factors for mean monthly air temperature. MAAT in the climate change scenarios was within +/-0.12 C of the speci ed change factor from MAAT in the REF scenario. The thermal and hydrological evolution of rock glacier soils were simulated for 50 years under the climatic forcing of the REF scenario followed by 50 years under each climate change scenario. Mean annual ground surface temperature (MAGST), active layer depth (Dal), permafrost total ice content (IWEtot), and the potential summer runoff contribution (MELTsum) were quanti ed and compared before and after the onset of the climate change conditions. Air temperature increases in the climate change scenarios were amplified in MAGST. Stable rock glacier points were resistant to changes in Dal and IWEtot under any annual, summer, and winter mean air temperature increase of 1 C, and summer and winter mean air temperature increases of 3 C despite notable changes in MAGST and MELTsum. Under warming scenarios, the greatest increase in MELTsum occurred for high elevation rock glacier points with the mean possible runoff contribution increasing 88% under 3 C of warming, which corroborates with increased runoff from high elevation permafrost in the Colorado Rockies in recent decades.

Glaciated catchments increasingly accommodate rising populations. As glaciers are capable of modifying peak flows and releasing floodwaters, understanding and developing models of subglacial water storage and release has significance to the safety of resident populations and land use decision-making. Glaciological and hydrometeorological processes play a critical role in determining water storage within the subglacial drainage system of Alpine glaciers. However, our understanding of spatial variations of these processes throughout the ablation season remains incomplete. Field results and modelling studies of the glacial hydrological system at Findelengletscher, Canton Valais, Switzerland are presented with a view to improving understanding of physical mechanisms controlling water flow within glacierised catchments. A physically-based model of surface runoff incorporating meltwater and precipitation has been developed. This model has limited data requirements using only air temperature, solar radiation, precipitation and elevation of the transient snow line in a simple, spatially distributed energy balance model. It has been used to predict surface runoff at an hourly resolution for the 1999 ablation season. Methodological advances have been made by creating conceptual models of water flow through the subglacial drainage system. Models are used for semi-quantitative interpretation of water level variations in boreholes, as surrogate measures of subglacial water pressures. The boreholes either directly intersect subglacial channels or hydraulically connect to subglacial channels through a subglacial sediment layer. Variations in borehole water levels are considered at both diurnal and seasonal timescales. Water storage has been calculated within the subglacial drainage network and interpretations are made of temporal variations in subglacial water storage. Borehole water levels indicate that the glacier subsole can be spatially separated into those areas that are hydraulically connected or unconnected to the subglacial drainage system. Hydraulically connected areas may further be subdivided into areas of efficient and inefficient subglacial drainage. These may intermittently connect and influence water balance within a glacier. Increasing and decreasing trends in water balance cycles are initiated by glaciohydrological mechanisms. These control the activity of intermittent hydraulic connections between efficient and inefficient areas of subglacial drainage. Connections form in response to two hydrometeorological factors: high elevation rainfall and short duration decreases in elevation of either the snowline or the 0°C isotherm. Increasing trends in water balance over successive days are associated with preferential routing of inputs into, and retention within, hydraulically inefficient areas of the subglacial drainage system. Occasionally the release of water from temporary subglacial storage is not synchronous with either hydrometeorological causal factor. Measurements of fall-line velocity and vertical displacement suggest that basal sliding may alter preferential subglacial flow pathways. However, uncertainty exists as to whether such changes may be the result of lagged effects of either high water pressures from rainfall or low water pressures from low daily surface runoff. These uncertainties are due to system response times affecting the time taken to transfer longitudinal strain within glacier ice. In the late ablation season the potential for rapid surface runoff over the annual maximum snowfree area within the catchment is high. In the event of a large rainfall event the capacity of a tunnel-conduit system to discharge may have decreased sufficiently to cause temporary retention of a large proportion of surface runoff, predominantly within distributed drainage. Temporary storage followed by re-integration of hydraulic connections formed earlier in the ablation season, increases the potential for proportionally large discharge events (relative to the volumes of inputs) in the late ablation season. Flooding in glacierised basins becomes more likely as a result.

Many diverse microbes have been detected in or isolated from glaciers, including novel taxa exhibiting previously unrecognized physiological properties with significant biotechnological potential. Of 29 unique phylotypes isolated from Victoria Upper Glacier, Antarctica (VUG), 12 were related to the poorly studied bacterial genus Hymenobacter including several only distantly related to previously described taxa. Further study of these microorganisms revealed genotypic, phenotypic, morphological and chemotaxonomic divergence from named species and suggested that they likely represent novel Hymenobacter species. These studies also indicated, however, that the systematics of Hymenobacter and related microorganisms is more complex than previously realized, and may exhibit poorly defined species boundaries due to cosmopolitan dispersal, significant rates of horizontal gene transfer and reintroduction of archived genotypes, e.g., from glacial ice. These processes are reflected in the carotenoid composition of Hymenobacter and related organisms, which includes several novel methyl- and xylosyl-derivatives of 2'-hydroxyflexixanthin with distributions indicative of horizontal gene transfer or differential gain and/or loss of terminal biosynthetic pathway steps. These processes have been previously underappreciated in assessments of microbial carotenoid diversity and suggest the need for fine-scale phylogenetic study of carotenoid distribution in other microbial taxa. Further comparative genomics-based evaluation of microbial carotenoid biosynthesis indicated its wide phylogenetic distribution and diversification, controlled by several lineage-specific modes of evolution including horizontal transfer, de novo enzyme evolution followed by differential gene loss, co-evolution with biochemically associated structures and elevated mutation rates. The latter especially interacts with horizontal transfer depending on metabolic pathway topology, exemplified by the evolution of purple bacterial carotenoid biosynthesis. Exploration of VUG microbial diversity, therefore, not only revealed novel taxa and biotechnologically interesting compounds but also spurred broader evaluation of the mechanisms of metabolic pathway evolution applicable to many other taxa and biochemical pathways. / Microbiology and Cell Biotechnology

Canadian High Arctic terrestrial ice masses and the polar atmosphere evolve co-dependently, and interactions between the two systems can lead to feedbacks, positive and negative. The two primary positive cryosphere-atmosphere feedbacks are: 1) The snow/ice-albedo feedback (where area changes in snow and/or ice cause changes in surface albedo and surface air temperatures, leading to further area changes in snow/ice); and 2) The elevation - mass balance feedback (where thickness changes in terrestrial ice masses cause changes to atmospheric circulation and precipitation patterns, leading to further ice thickness changes). In this thesis, numerical experiments are performed to: 1) quantify the magnitudes of the two feedbacks for chosen Canadian High Arctic terrestrial ice masses; and 2) to examine the direct and indirect consequences of surface air temperature changes upon englacial temperatures with implications for ice flow, mass flux divergence, and topographic evolution. Model results show that: a) for John Evans Glacier, Ellesmere Island, the magnitude of the terrestrial snow/ice-albedo feedback can locally exceed that of sea ice on less than decadal timescales, with implications for glacier response times to climate perturbations; b) although historical air temperature changes might be the direct cause of measured englacial temperature anomalies in various glacier and ice cap accumulation zones, they can also be the indirect cause of their enhanced diffusive loss; c) while the direct result of past air temperature changes has been to cool the interior of John Evans Glacier, and its bed, the indirect result has been to create and maintain warm (pressure melting point) basal temperatures in the ablation zone; and d) for Devon Ice Cap, observed mass gains in the northwest sector of the ice cap would be smaller without orographic precipitation and the mass balance – elevation feedback, supporting the hypothesis that this feedback is playing a role in the evolution of the ice cap.

Thesis (Ph. D.)--Texas State University-San Marcos, 2007. / Vita. Appendices: leaves 178-213. Includes bibliographical references (leaves 214-234).