Vulcões ativos na Antártica contrastam com a paisagem predominantemente gelada do continente. Eles fornecem condições únicas capazes de selecionar uma grande variedade de adaptações microbianas. A Ilha Deception localiza-se na região da Península Antártica e difere de outros vulcões antárticos especialmente pela influência marinha e temperaturas mais elevadas. Foram coletadas amostras de sedimentos associados a fumarolas e geleiras em dois sítios geotermais de Deception, com temperaturas variando entre 0°C a 98°C. Diferentes técnicas independentes de cultivo foram empregadas com o intuito de entender como as comunidades microbianas respondem as variações ambientais extremas produzidas pela atividade vulcânica. Os resultados indicaram que a co-ocorrência de arqueias hipertermófilas e suas adaptações com micro-organismos metabolicamente diversos adaptados a regiões geladas representa uma estrutura de comunidades única para ecossistemas antárticos. Este trabalho forneceu dados ineditos sobre questoes centrais de diversidade e adaptacao microbiana a ambientes geotermais polares. / Active volcanoes in Antarctica contrast with the predominately icy landscape. They harbor unique conditions capable to select an extreme range of microbial adaptations. Deception Island is located in the Antarctic Peninsula region and differs from other Antarctic volcanoes specially by its higher temperatures and marine influence. We collected sediment samples associated to active fumaroles and glaciers on two geothermal sites of Deception Island, with temperatures ranging from 0°C to 98°C. Different cultivation-indepedent techniques were used to understand how microbial communities respond to extreme environmental variations produced by volcanic activity. The results indicate that co-occurrence of hyperthermophiles and their specific adaptations with metabolically diverse cold-adapted micro-organisms represents a unique community structure for antarctic ecosystems. This study provided primordial data on central questions about microbial diversity and adaptation to polar geothermal environments.

Face au déclin récent des glaciers de montagne, un suivi régulier à l'échelle globale est nécessaire mais n'est pas réalisable par des campagnes de terrain. Nous montrons dans cette thèse que l'imagerie satellitaire haute résolution est une solution pour observer l'évolution dynamique et volumétrique des glaciers. <br />Les vitesses de surface des glaciers du Mont-Blanc montrent des fluctuations à court terme que nous relions à l'intensité de la fonte et à l'hydrologie sous-glaciaire. Sur le long terme, un ralentissement important (30 à 40%) suggère une réponse dynamique des glaciers aux changements climatiques. <br />Pour les glaciers alpins, les pertes de glace dans les zones basses s'accélèrent lors des dix dernières années alors qu'à haute altitude l'épaisseur glaciaire ne varie presque pas. Un fort amincissement à basse altitude est aussi observé en Islande et en Himalaya entre 1998-9 et 2004. Aussi, la fonte de ces glaciers expliquerait 5% de l'élévation récente

Situés dans une région clé pour la dynamique du climat global, les glaciers tropicaux sont de très bons indicateurs de la variabilité climatique. Ce travail a permis de spatialiser les modèles de bilan d'énergie CROCUS (pour la neige et la glace) et ISBA (pour le sol non enneigé) sur le bassin versant du glacier Zongo (16°S, 3.3 km2, Bolivie), englacé à 63 % et suivi par le SO/ORE GLACIOCLIM. Ainsi, des jeux de données nivo-météorologiques complets ont été constitués du 01/09/2004 au 31/03/2006 en accordant une attention particulière aux lames d'eau et aux phases des précipitations. Le modèle CROCUS-ISBA a été adapté pour simuler le manteau neigeux éphémère de la moraine et les résultats ont été validés sur plusieurs sites de mesures. Sur le glacier, le modèle CROCUS a permis de simuler correctement le bilan de masse local mesuré par les balises d'ablation. Ensuite, les modèles ont été étendus à l'ensemble du bassin versant et alimentés par les données météorologiques spatialisées. Le bilan net spécifique du glacier simulé est validé par celui évalué par photogrammétrie. Les débits à l'exutoire du bassin versant et leur saisonnalité sont bien restitués par le modèle (8% d'erreur sur les volumes d'eau pour toute la période, critère de Nash quotidien de 0.63). De nombreux résultats sont présentés sur le coefficient d'écoulement de la moraine, la contribution du glacier par tranche d'altitude et la réponse du bassin versant à deux saisons humides contrastées. Cet outil permet ainsi de mieux évaluer et comprendre les processus responsables de la fonte sur le glacier et sur les moraines et de quantifier leurs contributions respectives à la ressource en eau locale.

This thesis is focused on determining the rate at which the climate of western North America (WNA) has changed in recent history, and looks at the impact that projected future climatic changes will have on a large glaciated watershed in the Canadian Rocky Mountains. The rate of change over WNA is quantified for 485 climate stations for the period 1950-2005 using indicators developed by the World Meteorological Organization (WMO). Results of the analysis show statistically significant historical trends across the study area. To gauge the effect of climate change on glaciers, a mass balance model was developed and integrated with the University of Lethbridge GENESYS hydrometeorological model. GCM future climate scenarios were used to model change in the Upper North Saskatchewan River Basin through 2100. Results forecast dramatic declines (> 80%) in total glacier area, ice volume, and streamflow contribution by 2100. / ix, 137 leaves ; 29 cm

Pollen records from southeastern Vancouver Island, British Columbia, show changes in vegetation and climate from the late Olympia Interstade through the Fraser Glaciation. This study provides important insights into phytogeographic patterns of Pacific Northwest flora, leads to an enhanced understanding of processes affecting present-day ranges of several plant taxa, and provides a historical perspective on the origin of coastal alpine ecosystems. Evidence for a previously unrecognized glacial advance in the region at ~21,000 14C yr BP, herein called the Saanich glacier, is provided. The results reveal widespread habitat and food sources suitable for the mega fauna that lived on southern Vancouver Island during the last glaciation. Vegetation during the Fraser Glaciation represented a mosaic of plant communities across a heterogeneous and productive landscape. Pollen spectra indicate that plant assemblages, dominated by Poaceae and Cyperaceae, were widespread. Similarities to tundra in northern Alaska and high elevation sites in British Columbia were detected. Vegetation varied geographically in the late Olympia (ca. 33,500-29,000 14C yr BP). Grassy uplands with scattered trees and local moist meadows occurred at Qualicum Beach under mesic and cool conditions, while cold and dry grass tundra prevailed at Skutz Falls. Increased non-arboreal pollen percentages at Qualicum Beach, 29,000 14C yr BP, reflect expansion of grassy meadows with diverse herbs under a cool and dry climate at the onset of the Fraser Glaciation. At Qualicum Beach between 25,160-24,190 14C yr BP, sedge wetlands were surrounded by open, dry uplands. Concurrently at Osborne Bay, Pinus-Picea-Abies-Poaceae parkland occurred. Dry and cold climate intensified as the Fraser Glaciation progressed after 24,000 14C yr BP and non-arboreal communities expanded. At Cordova Bay, cold and dry tundra or parkland in upland sites, and sedge wetlands on an aggrading floodplain are recorded. Sparse tree cover and grass-tundra surrounded a floodplain at Skutz Falls around 21,000 14C yr BP under cool and dry climate. Subalpine-like Picea-Abies-Pinus parkland and moist, species-rich grassland meadows occurred at McKenzie Bight at the same time. A sedge wetland occupied the site of deposition, and was periodically inundated as lake levels fluctuated. Upland grasslands at Cordova Bay are recorded between 21,600–19,400 14C yr BP, while local ponded areas developed on an aggrading floodplain at sea level. From 19,400-19,300 14C yr BP, parkland at Cordova Bay developed as climate moistened and warmed at the time of the Port Moody Interstade known from the Fraser Lowland. Abundant marine dinoflagellate cysts between 21,600–19,400 14C yr BP, reveal a high sea level stand and strong marine influence at Cordova Bay. Glacioisostatic depression of the crust on the east side of Vancouver Island is the most probable explanation. The presence of pollen-bearing glacio-lacustrine sediments at McKenzie Bight around 21,000 14C yr BP at ~93 m and contemporaneous isostatic crustal depression at Cordova Bay strongly suggest a major glacial body in the region at the same time as the Coquitlam advance in the Lower Mainland. Ice-free landscapes may have occurred on southern Vancouver Island through the Fraser glaciation beyond the Saanich glacier ice limits. / Graduate

Vulcões ativos na Antártica contrastam com a paisagem predominantemente gelada do continente. Eles fornecem condições únicas capazes de selecionar uma grande variedade de adaptações microbianas. A Ilha Deception localiza-se na região da Península Antártica e difere de outros vulcões antárticos especialmente pela influência marinha e temperaturas mais elevadas. Foram coletadas amostras de sedimentos associados a fumarolas e geleiras em dois sítios geotermais de Deception, com temperaturas variando entre 0°C a 98°C. Diferentes técnicas independentes de cultivo foram empregadas com o intuito de entender como as comunidades microbianas respondem as variações ambientais extremas produzidas pela atividade vulcânica. Os resultados indicaram que a co-ocorrência de arqueias hipertermófilas e suas adaptações com micro-organismos metabolicamente diversos adaptados a regiões geladas representa uma estrutura de comunidades única para ecossistemas antárticos. Este trabalho forneceu dados ineditos sobre questoes centrais de diversidade e adaptacao microbiana a ambientes geotermais polares. / Active volcanoes in Antarctica contrast with the predominately icy landscape. They harbor unique conditions capable to select an extreme range of microbial adaptations. Deception Island is located in the Antarctic Peninsula region and differs from other Antarctic volcanoes specially by its higher temperatures and marine influence. We collected sediment samples associated to active fumaroles and glaciers on two geothermal sites of Deception Island, with temperatures ranging from 0°C to 98°C. Different cultivation-indepedent techniques were used to understand how microbial communities respond to extreme environmental variations produced by volcanic activity. The results indicate that co-occurrence of hyperthermophiles and their specific adaptations with metabolically diverse cold-adapted micro-organisms represents a unique community structure for antarctic ecosystems. This study provided primordial data on central questions about microbial diversity and adaptation to polar geothermal environments.

Satellite imagery and volume-area scaling are used to asses the glacier area and ice volume of Iceland from the Little Ice Age maximum to present day, obtaining a final result in sea level rise between 1890 - 2015. The Little Ice Age was a time of regional cooling, with glaciers reaching their maximum extent (~1890 for Iceland) with warming and glacier retreat after this period ended. Ice volume estimates are important to know due to their relevance in potential sea level rise calculations. Understanding both of these estimations for Iceland connects the impact a changing climate has on regional and global scales. Different scaling parameters used in the volume-area scaling approach to determine ice volume and ultimately sea level equivalents highlight the range of estimates acquired and point out the need in choosing appropriate values based on glacier region. A comparison to using mass balance measurements for volume estimates is also noted, showing differences in ice volume loss over past and present time periods. The Icelandic glacier area for present day is an updated value from previous studies at 10,803 ± 83 km2 and a first ever reported Icelandic Little Ice Age maximum glacier area of 12,201 ± 91 km2. For potential sea level rise, it is found the most reliable estimate from the volume- area scaling assessment is 2.67 mm from the Little Ice Age maximum to present day, with a yearly contribution since 1890 of 0.02 mm. / Satellitbilder och volym-area skalningsmetoden användes för att uppskatta glaciärarea och isvolym på Island från Lilla istiden till nutid, för att få fram hur stor höjningen av havsnivån varit under denna tidsperiod (1890 – 2015). Den lilla istiden var en tid av regional kylning då glaciärer nådde sin maximala utsträckning (~1890 för Island) följt av en snabb reträtt efter att denna period slutade. Uppskattningen av isvolym är viktigt att veta på grund av dess relevans i potentiella beräkningar av höjningen av havsnivån. Att förstå båda dessa uppskattningar för Island är kopplat till den påverkan ett förändrat klimat har på regional och global nivå. De olika skalparametrar som använts i volym-area skalningsmetoden för att bestämma volymen av is, och dess motsvarigheter i havsnivå, gav en rad av olika uppskattningar. Detta pekar på behovet att välja ett lämpligt parametervärde baserat på glaciärregionen. En jämförelse med att använda mätningar av massbalans för volymuppskattningar gjordes också, vilket visar skillnader i isvolymförlust över tidigare och nuvarande tidsperioder. Dagens värde på den isländska glaciärarean är uppdaterat från tidigare studier på 10,803 ± 83 km2 och den första rapporterade maximala isländska glaciärarean från Lilla istiden på 12,201 ± 91 km2. För potentiell höjning av havsnivån, har man funnit att den mest tillförlitlig uppskattning från volym-area skalningsmetoden är 2,67 mm från Lilla istidens maximum till nutid, med ett årligt bidrag sedan 1890 av 0,02 mm. (Översättning Cecilia Bayard.)

Sea level rise concerns millions of people in coastal areas across the globe. One of the largest uncertainties to project future sea level rise is the frontal ablation (accounting for calving and submarine melt) at marine ice margins, around the Greenland and Antarctic Ice Sheet. High rates of frontal ablation have been observed to imply, through loss of the buttressing effect but not limited to it, increased mass loss from marine terminating glaciers and hence, associated sea level rise. This study focuses on calving processes at a freshwater lake in northern Sweden, which represents a simpler environment to study calving processes than the marine one, because impacts of tides, salinity, and circulation (all known to be relevant at marine ice-ocean boundaries) can be neglected. A multi-method approach to quantify and characterize calving events is presented here, exploring and analysing the underwater acoustic soundscape at a calving glacier front, in connection with optical, image-based methods such as time- lapse photography, and photogrammetry based on footage acquired by an uncrewed aerial vehicle (UAV). An acoustic detector is developed, tested and applied to data set acquired during 2020, and results indicate that the acoustic detector can be an important complement in the range of tools used to observe, and quantify, calving. Applied in remote locations, where continuous monitoring is difficult and where optical methods are of limited use, collecting acoustic data and monitoring calving by means of its acoustic signature could render insights previously not available (because of lacking data and methodology).

This research documents the Holocene glacial history of Mount Hood, Cascade Mountains, Oregon by analyzing a set of three lateral moraines abutting Eliot Glacier, the largest glacier on the mountain. This study seeks to: 1) establish the relative ages of these lateral moraines and 2) determine if these features represent distinct glacial advances. The hypothesis is that the lateral moraines for Eliot Glacier represent three distinct periods of glacial advance based on their position relative to the current glacier and other diagnostic indicators. Soil profiles of three positions (shoulder, backslope, and footslope) on the distal side of each lateral moraine were described in the field and samples were taken from each horizon for laboratory analyses of pH and particle size. The results of the soil analysis show that the soils developing on the moraine closest to the current glacier are poorly developed and significantly younger than the other two features. The closest moraine likely dates to the Little Ice Age (600-150 YBP) and has soils with an A/C profile and a classification of Andic Cryopsamment. The soils on the middle and furthest moraines from the glacier are similar in the profile sequence (Andic Haplocryepts). Silt bulges were noted in the mid-slope pits. The furthest moraine has deeper horizons and more color development than the middle moraine. Ash layers were found in the backslope soil profile (36-51cm deep) on the middle moraine. Additional lab testing confirms the ash layers originated from Mount Hood, but no date can be assigned. The eruptive history of Mount Hood points to the Timberline eruptive period (1,500 YBP) as a likely candidate for one of the ash deposits. This evidence suggests the middle moraine was actively forming during this period and is intermediate in age between the furthest moraine and the Little Ice Age Moraine; hence, this sequence of moraines indicates three distinct periods of glacial advance in the Neoglacial.

Eight glaciers, covering an area of 1.63 km2, reside on the northern and northeastern slopes of the Goat Rocks tallest peaks in the Cascades of central Washington. At least three glacial stands occurred downstream from these glaciers. Closest to modern glacier termini are Little Ice Age (LIA) moraines that were deposited between 1870 and 1899 AD, according to the lichenometric analysis. They are characterized by sharp, minimally eroded crests, little to no soil cover, and minimal vegetation cover. Glacier reconstructions indicate that LIA glaciers covered 8.29 km2, 76% more area than modern ice coverage. The average LIA equilibrium line altitude (ELA) of 1995 ± 70 m is ~150 m below the average modern ELA of 2149 ± 76 m. To satisfy climate conditions at the LIA ELA, the winter snow accumulation must have been 8 to 43 cm greater and mean summer temperatures 0.2 to 1.3 ºC cooler than they are now. Late Pleistocene to early Holocene (LPEH) aged moraines are located between 100 and 400 m below the LIA deposits. They have degraded moraine crests, few surface boulders, and considerable vegetation and soil cover. Volcanic ashes indicate LPEH moraines were deposited before 1480 AD while morphometric data suggest deposition during the late Pleistocene or early Holocene. The average LPEH ELA of 1904 ± 110 m is ~ 240 m and ~90 m below the modern and LIA ELAs, respectively. The climate change necessary to maintain a glacier with an ELA at that elevation for LPEH conditions requires the winter accumulation to increase by 47 to 48 cm weq and the mean summer temperature to cool by 1.4 to 1.5 ºC. Last glacial maximum (LGM) moraines are located more than 30 km downstream from modern glacial termini. They are characterized by hummocky topography, rounded moraine crests, complete vegetation cover, and well developed soil cover. Moraine morphometry, soil characteristics, and distance from modern glacial termini indicate that deposition occurred at least 15 ka BP during an expansive cooling event, the last being the LGM. The LGM ELA of 1230 m is ~920 m below the modern ELA. The climate change necessary to maintain a glacier with an ELA at that elevation for LGM conditions requires the mean summer temperature to cool by 5.6 ºC with no change in precipitation.