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1
Yang, Lei. "Greenland ice sheet change surface climate variability and glacier dynamics /." The Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=osu1180121203.
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Pingree, Katherine A. "The Greenland Ice Sheet: Reconstruction under Modern-Day Conditions and Sensitivity to the North Atlantic Oscillation." Fogler Library, University of Maine, 2010. http://www.library.umaine.edu/theses/pdf/PingreeKA2010.pdf.
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Goldsack, Anne Elizabeth. "Oceanographic controls on glaciers in southeast Greenland." Thesis, Swansea University, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.678487.
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Beal, Samuel A. "Chemical weathering along the Greenland ice sheet margin /." Norton, Mass. : Wheaton College, 2009. http://hdl.handle.net/10090/8391.
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Abbott, Peter Michael. "Tephrochronology of the Greenland ice-cores and the North Atlantic Region during Marine Isotope Stage 4." Thesis, Swansea University, 2010. https://cronfa.swan.ac.uk/Record/cronfa42515.
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The occurrence of several high-magnitude abrupt climatic changes during the last glacial period (~120-10 ka BP) was first recognised within the Greenland deep ice-core records. Subsequent identification of similar climatic variations has demonstrated the potential global significance of these events. Three of these millennial-scale events occurred during Marine Isotope Stage (MIS) 4 (~79-59 ka BP), a period characterised by cooler global temperatures. An understanding of the forcing mechanisms and the environmental responses to these events is currently unattainable due to chronological uncertainties and the inability to precisely synchronise disparate records. Tephrochronology, however, has the potential to facilitate high-precision ice-marine correlations by tracing isochronous horizons between different sequences spanning this period. This potential is demonstrated through the construction of the first tephrochronological framework for MIS 4 within the North Atlantic region. Fourteen cryptotephra horizons are identified within the NGRIP and GRIP ice-cores and the MD04-2822 marine core. Both major and trace element compositions are presented for these previously unknown tephra horizons and form the backbone of this framework. In addition, high-precision, independent age estimates have been assigned to the horizons identified within the ice-core sequences. This framework represents a significant first step towards the regional and potentially hemispheric synchronisation of MIS 4 climatic archives. As well as providing the first evidence for the activity of Icelandic volcanic systems during MIS 4, this framework also demonstrates the widespread dispersal of basaltic-trachybasaltic products from the Jan Mayen volcanic region and potentially the deposition of Japanese volcanic material over Greenland. In addition, investigations of laser ablation inductively coupled plasma mass spectrometry have demonstrated that reliable trace element characterisations can be obtained from tephra shards?20 ?m in diameter, which opens up new possibilities for the incorporation of this technique in distal tephra studies.
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Ashcraft, Ivan S. "Microwave Remote Sensing of the Greenland Ice Sheet: Models and Applications." Diss., CLICK HERE for online access, 2004. http://contentdm.lib.byu.edu/ETD/image/etd532.pdf.
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Candela, Salvatore G. "Greenland Ice Sheet Changes in Rates of Surface Elevation Change between 1978 and 2015." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1543498988161871.
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Clarke, Amy. "Lake records of Holocene climate change from west Greenland." Thesis, University of Liverpool, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.250439.
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Duncan, Kyle. "Reconstructing surface elevation changes for the Greenland Ice Sheet (1993-2013) and analysis of Zachariae Isstrom, northeast Greenland." Thesis, State University of New York at Buffalo, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=1600748.
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<p> Previous studies investigating the velocity and elevation change records of the Greenland Ice Sheet (GrIS) revealed rapid and complex changes. It is therefore imperative to determine changes with both high spatial and temporal resolutions. By fusing multiple laser altimetry data sets, the Surface Elevation Reconstruction and Change (SERAC) program is capable of reconstructing surface elevation changes with high spatial and temporal resolution over the entire GrIS. The input data include observations from NASA’s Ice, Cloud and land Elevation Satellite (ICESat) mission (2003-2009) as well as data collected by NASA’s Airborne Topographic Mapper (ATM) (1993-2013) and Land, Vegetation and Ice Sensor (LVIS) (2007-2012) airborne laser altimetry systems. This study extends the record of surface elevation changes over the GrIS by adding 2012 and 2013 laser altimetry data to the previous 1993-2011 record. Extending the record leads to a new, more accurate and detailed altimetry record for 1993-2013. </p><p> Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) Digital Elevation Models (DEMs) are fused with laser altimetry data over Zachariæ Isstrøm, northeast Greenland to analyze surface elevation changes and associated thinning rates during 1978-2014. Little to no elevation change occurred over Zachariæ Isstrøm from 1978-1999, however, from 1999-2014 elevation changes near the calving front became increasingly negative and accelerated. Calving front position showed steady retreat and grounding line position has been retreating towards the interior of the ice sheet at an increasing rate from 2010-2014 when compared to the 1996-2010 period. The measured elevation changes near the calving front have brought a large portion of the glacier close to the height of flotation. If the current thinning trend continues this portion of the glacier will reach flotation within the next 2-5 years allowing for further retreat and increased vulnerability to retreat for sections of the glacier further upstream.</p>
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Thomas, Elizabeth Ruth. "High-resolution analysis of rapid climate change from Greenland ice cores." Thesis, Open University, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.435909.
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Comeau, Laura Elizabeth Lamplugh. "Snow modelling for understanding human ecodynamics in periods of climate change." Thesis, University of Edinburgh, 2013. http://hdl.handle.net/1842/8012.
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This thesis tests and applies a new, physically based snow distribution and melt model at spatial scales of tens of metres and temporal scales of days across sub-arctic landscapes, in order to assess the significance of snow variability in sub-arctic human ecodynamics at resolutions relevant to human activities. A wider goal is to contribute to planning in the face of future climate change. Model tests are undertaken based on original field data collected in Sweden and Norway, and secondary data from Idaho, France and Greenland. Model applications focus on the ‘completed experiment’ of the medieval Norse in Greenland, a comparatively isolated population that relied on a combination of pastoralism and hunting for survival. A combination of local calibration based on contemporary meteorological data, customised climate reconstructions based on GCM data, new archaeological survey and new DEM are used in order to apply the model. This thesis shows, for the first time, the likely range of snow depth and duration experienced across the medieval Norse Greenland landscape as a result of climate and vegetation change. Results show that increases in snow cover could have been significant drivers of transformative change in Norse Greenland, and are therefore likely to be key in understanding the potential impact of future climate changes on similar sub-arctic and relatively marginal communities. Selected model analyses simulate the total spring (April-June) snow cover at the homefields to range from 32% cover lasting 6 days in the most favourable climate to 100% cover lasting 45 days in the most unfavourable climate at key elite inner fjord farms. At the more isolated outer fjord farms, total spring snow cover ranges from 33% cover lasting 10 days in the most favourable climate to 100% cover lasting 60 days in the most unfavourable climate. Increased climate variance and recovery times, as experienced by the Norse, are potential early warning signals of threshold-crossing change. Model results show that these signals could have been masked for the Norse decision making elite because they were located in the most favourable and least snow covered locations. Masking could have been further increased through the intensified seal hunting implemented by the Norse as an adaption strategy, and these actions could have developed into a rigidity trap. When the conjunctures of the 15th century developed in terms of increased sea ice, snow cover, storminess, culture contact, changing trade and sea level rise, it was too late to develop different responses. Whilst current populations have improved technology and knowledge relative to the Norse Greenlanders, there is a risk that adaptations will lack long-term utility, spatially restricted indications of change may be ignored, and rigidity traps develop. This thesis provides an additional tool for understanding a key element of both the past and possible futures of subarctic human ecodynamics.
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King, Michalea Dianne. "Seasonal to Multidecadal Drivers of Variability at Greenland Outlet Glaciers." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1595450113904316.
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Kobashi, Takuro. "Greenland temperature, climate change, and human society during the last 11,600 years." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2007. http://wwwlib.umi.com/cr/ucsd/fullcit?p3249924.
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Thesis (Ph. D.)--University of California, San Diego, 2007.<br>Title from first page of PDF file (viewed April 4, 2007). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references.
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Jung, Jihoon. "Temporal and spatial characteristics of Greenland ice sheet net snow accumulation (1781–2008)." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1343848275.
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Söderström, Ellen. "Men, masculinities and climate change : A study of climate change impacts in cases from Greenland, Australia Peru and South Africa." Thesis, Linnéuniversitetet, Institutionen för samhällsstudier (SS), 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-44709.
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‘Climate change is not gender neutral’ is a statement that has gained more recognition within the climate change debate over the last decade. This has resulted in a new field of research called gender and climate change. The mainstream gender and climate change debate has earlier almost exclusively focused on women’s vulnerability. A brief reading of the literature clearly shows that men are rarely observed in this context. The objective of this thesis is to broaden the understanding of the relation between gender and climate change by bringing men into the discussion. I have selected four cases/countries where existing research on men’s gendered experiences of climate change are mentioned. These take place in Greenland, Australia, Peru and South Africa. The result show five common findings between the cases: gendered responsibilities, changing traditional gender roles, psychological impacts, alcohol consumption and violence against women. The concept hegemonic masculinities is utilized as a framework used to understand why men are negatively affected by climate change. Masculine norms of attitudes and behavior identified in the multiple case studies are invulnerability and unwillingness to seek help. The analysis show that in times of climate variability can masculine norms be damaging for both men and women. A second analytical framework, the gender transformative approach brings the analysis to critically reflect upon masculinities and climate change as functions of power. From this perspective this thesis concludes that the gender and climate change discourse needs to move beyond a focus on women’s vulnerabilities, which divide the world into two classes: women as victims and men as perpetrators. This approach rather urge for a focus on the structures of power and domination within laws, behaviors and institutions that generates injustices.
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Huffman, Demie R. "Refractory black carbon at Crawford Point, Greenland: Implications for mitigation policy." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1534523019443308.
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Robinson, Alexander. "Modeling the Greenland Ice Sheet response to climate change in the past and future." Phd thesis, Universität Potsdam, 2011. http://opus.kobv.de/ubp/volltexte/2011/5043/.
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The Greenland Ice Sheet (GIS) contains enough water volume to raise global sea level by over 7 meters. It is a relic of past glacial climates that could be strongly affected by a warming world. Several studies have been performed to investigate the sensitivity of the ice sheet to changes in climate, but large uncertainties in its long-term response still exist. In this thesis, a new approach has been developed and applied to modeling the GIS response to climate change. The advantages compared to previous approaches are (i) that it can be applied over a wide range of climatic scenarios (both in the deep past and the future), (ii) that it includes the relevant feedback processes between the climate and the ice sheet and (iii) that it is highly computationally efficient, allowing simulations over very long timescales.
The new regional energy-moisture balance model (REMBO) has been developed to model the climate and surface mass balance over Greenland and it represents an improvement compared to conventional approaches in modeling present-day conditions. Furthermore, the evolution of the GIS has been simulated over the last glacial cycle using an ensemble of model versions. The model performance has been validated against field observations of the present-day climate and surface mass balance, as well as paleo information from ice cores. The GIS contribution to sea level rise during the last interglacial is estimated to be between 0.5-4.1 m, consistent with previous estimates. The ensemble of model versions has been constrained to those that are consistent with the data, and a range of valid parameter values has been defined, allowing quantification of the uncertainty and sensitivity of the modeling approach.
Using the constrained model ensemble, the sensitivity of the GIS to long-term climate change was investigated. It was found that the GIS exhibits hysteresis behavior (i.e., it is multi-stable under certain conditions), and that a temperature threshold exists above which the ice sheet transitions to an essentially ice-free state. The threshold in the global temperature is estimated to be in the range of 1.3-2.3°C above preindustrial conditions, significantly lower than previously believed. The timescale of total melt scales non-linearly with the overshoot above the temperature threshold, such that a 2°C anomaly causes the ice sheet to melt in ca. 50,000 years, but an anomaly of 6°C will melt the ice sheet in less than 4,000 years. The meltback of the ice sheet was found to become irreversible after a fraction of the ice sheet is already lost – but this level of irreversibility also depends on the temperature anomaly.<br>Das grönländische Inlandeis (GIS) besteht aus einem Wasservolumen das ausreicht, um den globalen Meeresspiegel um 7 Meter ansteigen zu lassen. Es ist ein Relikt der vergangenen Eiszeit, das in einer zunehmend wärmer werdenden Welt stark in Mitleidenschaft gezogen werden könnte. In der vorliegenden Dissertation ist ein neues Verfahren zur Modellierung des Antwortverhaltens des Inlandeises auf Klimaänderungen entwickelt und angewendet worden. Die Vorteile des neuen Verfahrens im Vergleich zu den bisherigen Verfahren sind, (i) dass es über einen groen Bereich von Klimaszenarien (sowohl für die ferne Vergangenheit als auch für die Zukunft) anwendbar ist, (ii) dass es die wesentlichen Rückkopplungsprozesse zwischen Klima und Inlandeis enthält und (iii) dass es wegen seiner guten Rechenzeiteffizienz Simulationen über sehr lange Zeitskalen erlaubt.
Das neue Modell (REMBO) ist für die Modellierung des Klimas und der Massenbilanz an der grönländischen Oberfläche entwickelt worden und stellt ein verbessertes Verfahren im Vergleich zu den bisherigen dar. Die Entwicklung von GIS über den letzten glazialen Zyklus ist mittels eines Ensembles von verschiedenen Modellversionen simuliert worden. Anschließend ist die Tauglichkeit der Modellversionen durch Vergleich mit Beobachtungsdaten des gegenwärtigen Klimas und der Oberflächenmassenbilanz, sowie mit paleoklimatischen Rekonstruktionen von Eisbohrkernen verifiziert worden. Der Anteil von GIS am Meeresspiegelanstieg während des letzten Interglazials ist im Bereich von 0.5 bis 4.1 m berechnet worden, was konsistent mit bisherigen Schätzungen ist. Von den Ensemblesimulationen sind diejenigen ausgewählt worden, deren Ergebnisse gut mit den Daten übereinstimmen. Durch die Auswahl von geeigneten Modellversionen sind gleichzeitig die Unsicherheiten der Parameterwerte begrenzt worden, so dass sich nun mit dem neuen Verfahren die Sensitivität von GIS auf Klimaänderungen bestimmen lässt.
Mit den ausgewählten Modellversionen ist die Sensitivität von GIS auf langfristige Klimaänderungen untersucht worden. Es zeigt sich, dass das GIS ein Hystereseverhalten besitzt (d.h., eine Multistabilität für gewisse Klimazustände) und dass ein Temperaturschwellwert existiert. Bei Überschreiten des Schwellwertes bleibt das GIS nicht erhalten und wird langsam eisfrei werden. Der Temperaturschwellwert der globalen Mitteltemperatur relativ zur vorindustriellen Mitteltemperatur ist im Bereich 1.3-2.3°C ermittelt worden und liegt damit deutlich niedriger als bisher angenommen. Die Zeitdauer bis zum völligen Abschmelzen zeigt ein nichtlineares Verhalten hinsichtlich einer Erwärmung über den ermittelten Schwellwert. Eine Erwärmung von 2°C relativ zur vorindustriellen Zeit führt zu einem Abschmelzen nach 50.000 Jahren, aber eine Erwärmung um 6°C lässt das Inlandeis bereits nach 4.000 Jahren abschmelzen. Ein weiteres Ergebnis ist, dass der Abschmelzvorgang irreversibel werden kann, nachdem ein gewisser Anteil des Inlandeises abgeschmolzen ist – jedoch ist die Irreversibilität eines Abschmelzvorganges auch von der Temperaturanomalie abhängig.
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Wheelock-Davis, Emily J. "Elevation Changes in Greenland over Two Decades from Cross-Platform LIDAR Analysis." The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1366223499.
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Higgins, Lindsey. "Construction and Analysis of an Ice Core-Derived Melt History from West Central Greenland (1765-2006)." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1338303023.
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Carlzon, Linnéa, and Amanda Karlsson. "Extreme weather affects the peregrine falcon’s (Falco peregrinus tundrius) breeding success on South Greenland." Thesis, Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-35160.
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In order to understand the effects of climate change on the peregrine’s future prospects, we investigated the relationship between weather variables (extreme weather) and breeding success parameters for the peregrine in South Greenland. We defined two variables for comparison with weather data: young per known territory and nest success, i.e. proportion of known sites producing young, for each monitored year (N = 33). Weather data were obtained from two weather stations in the study area. From the weather data four extreme predictor variables were calculated: extreme low temperature, extreme precipitation, consecutive rainy days and total days with extreme weather. Peregrine breeding success (both parameters) was correlated negatively with number of days with extreme weather; the strongest correlation found was between total days in the season with extreme weather and breeding success. Low temperature and total days with extreme weather during the pre-laying and incubation period were also significantly negatively correlated with breeding success. Thereby, extreme weather is an important factor in explaining the peregrine’s breeding success. However, other factors also influence the breeding success, in the last few years there has been a strong downward trend but not an increase of extreme weather events during the same period.<br>Den globala uppvärmningen påverkar Arktis klimat vilket orsakar en snabbt föränderlig miljö för den Arktiska biotan. Effekten av klimatförändringarna är ökade väder variationer och extremer. Pilgrimsfalken är en väl studerad toppredator men få studier har undersökt hur extremt väder påverkar pilgrimsfalkens häckningsframgång i arktiska miljöer. Därför undersöker vi förhållandet mellan extrema väder och häckningsframgången för pilgrimsfalken på södra Grönland. Vi har i denna studie använt data om pilgrimsfalkens häckningsframgång på södra Grönland som sträcker sig från år 1981 och fram till 2015. Väderdata som använts för att kalkylera variablerna: extrem temperatur, extremt regn, regndagar i följd och totalt antal dagar med extremt väder har erhållits från två väderstationer inom studieområdet. Häckningssäsongen analyserades i sin helhet samt delades in i perioderna: “innan äggläggnings-”, “ruvnings-” och “ungar-i-boet-perioden”, vilka korrelerades mot vädervariablerna. Vi fann att dagar med extremt väder påverkar pilgrimsfalkens häckningsframgång negativt under hela säsongen samt under perioderna “innan äggläggning” och “ruvning”. Extrema väderhändelser kan alltså förklara variationer i häckningsframgången för pilgrimsfalken på södra Grönland. Resultatet indikerar även att andra faktorer påverkar häckningsframgången då det finns en stark nedåtgående trend i pilgrimsfalkens häckningsframgång men inte en ökning av extrema väderhändelser under samma period.
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Enderlin, Ellyn Mary. "Observations and Modeling of Greenland Outlet Glacier Dynamics." The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1372609057.
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Briere, Michelle. "Paleodemography of the North American Arctic, Subarctic, and Greenland in Relation to Holocene Climate and Environmental Change." Thesis, Université d'Ottawa / University of Ottawa, 2020. http://hdl.handle.net/10393/40013.
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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.
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Bakker, P., A. Schmittner, J. T. M. Lenaerts, et al. "Fate of the Atlantic Meridional Overturning Circulation: Strong decline under continued warming and Greenland melting." AMER GEOPHYSICAL UNION, 2016. http://hdl.handle.net/10150/622754.
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The most recent Intergovernmental Panel on Climate Change assessment report concludes that the Atlantic Meridional Overturning Circulation (AMOC) could weaken substantially but is very unlikely to collapse in the 21st century. However, the assessment largely neglected Greenland Ice Sheet (GrIS) mass loss, lacked a comprehensive uncertainty analysis, and was limited to the 21st century. Here in a community effort, improved estimates of GrIS mass loss are included in multicentennial projections using eight state-of-the-science climate models, and an AMOC emulator is used to provide a probabilistic uncertainty assessment. We find that GrIS melting affects AMOC projections, even though it is of secondary importance. By years 2090-2100, the AMOC weakens by 18% [-3%, -34%; 90% probability] in an intermediate greenhouse-gas mitigation scenario and by 37% [-15%, -65%] under continued high emissions. Afterward, it stabilizes in the former but continues to decline in the latter to -74% [+4%, -100%] by 2290-2300, with a 44% likelihood of an AMOC collapse. This result suggests that an AMOC collapse can be avoided by CO2 mitigation.
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Yang, Qian. "Applications of Satellite Geodesy in Environmental and Climate Change." Scholar Commons, 2016. http://scholarcommons.usf.edu/etd/6440.
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Satellite geodesy plays an important role in earth observation. This dissertation presents three applications of satellite geodesy in environmental and climate change. Three satellite geodesy techniques are used: high-precision Global Positioning System (GPS), the Gravity Recovery and Climate Experiment (GRACE) and Interferometric Synthetic Aperture Radar (InSAR). In the first study, I use coastal uplift observed by GPS to study the annual changes in mass loss of the Greenland ice sheet. The data show both spatial and temporal variations of coastal ice mass loss and suggest that a combination of warm atmospheric and oceanic condition drove these variations. In the second study, I use GRACE monthly gravity change estimates to constrain recent freshwater flux from Greenland. The data show that Arctic freshwater flux started to increase rapidly in the mid-late 1990s, coincident with a decrease in the formation of dense Labrador Sea Water, a key component of the deep southward return flow od the Atlantic Meridional Overturning Circulation (AMOC). Recent freshening of the polar oceans may be reducing formation of Labrador Sea Water and hence may be weakening the AMOC. In the third study, I use InSAR to monitor ground deformation caused by CO2 injection at an enhanced oil recovery site in west Texas. Carbon capture and storage can reduce CO2 emitted from power plants, and is a promising way to mitigate anthropogenic warming. From 2007 to 2011, ~24 million tons of CO2 were sequestered in this field, causing up to 10 MPa pressure buildup in a reservoir at depth, and surface uplift up to 10 cm. This study suggests that surface displacement observed by InSAR is a cost-effective way to estimate reservoir pressure change and monitor the fate of injected fluids at waste disposal and CO2 injection sites.
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Popp, Trevor J. "The speed and timing of climate change: Detailed ice core stable isotope records from NorthGRIP, Greenland and Mt. Moulton, West Antarctica." Connect to online resource, 2008. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3337142.
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Jeong, Seongsu. "Time Series Reconstruction of Surface Flow Velocity on Marine-terminating Outlet Glaciers." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1437602064.
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Lindeberg, Carola. "Long-term changes of mercury, lead and persistent organic pollutants in arctic environments." Doctoral thesis, Umeå : Department of Ecology and Environmental Science, Umeå Univ, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-1060.
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Nylund, Andreas. "A Lead (Pb) Mass-Balance Budget for a Dry Periglacial Catchment in West Greenland : Discussing the fate of pollutant Pb." Thesis, Umeå universitet, Institutionen för ekologi, miljö och geovetenskap, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-171856.
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Lead (Pb), occurs both naturally and as a pollutant in Arctic landscape systems. The ongoing climate change, especially pronounced in the Arctic, changes the premises for Pb transport and mobility. Thus, to predict future development of both natural and pollution Pb, an increased understanding of their storages and flows in an Arctic system is of interest. Here, a Pb mass-balance budget for an entire catchment in West Greenland was calculated. The budget shows that most Pb is stored in terrestrial soils (94%), while 6% of total catchment Pb is in lake sediments. Other Pb-pools are small in comparison (<1% combined). The entire catchment system has a negative balance, with annual inputs of 44 g Pb from precipitation and 67 g Pb from eolian deposition, while 150 g Pb is removed from the system (through sedimentation). Limited lake water outflow (o.15 g Pb yr-1) suggests that the catchment in its entirety acts as a Pb-sink. The terrestrial system, however (wet deposition input of 34 g Pb and hydrological export of 68 g Pb annually), is considered to be a Pb-source to the aquatic system. The magnitude of hydrological and eolian transport is similar, however the former is more important for pollution Pb transport where the latter is more important for natural Pb. The fate of pollutant Pb is determined by future climate change. Wetter conditions could lead to a prolonged export of Pb further down-stream. If drier conditions prevail, eolian transport will be more important and pollution Pb could stay in soils.
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Lindbäck, Katrin. "Hydrology and Bed Topography of the Greenland Ice Sheet : Last known surroundings." Doctoral thesis, Uppsala universitet, Luft-, vatten och landskapslära, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-259076.
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The increased temperatures in the Arctic accelerate the loss of land based ice stored in glaciers. The Greenland Ice Sheet is the largest ice mass in the Northern Hemisphere and holds ~10% of all the freshwater on Earth, equivalent to ~7 metres of global sea level rise. A few decades ago, the mass balance of the Greenland Ice Sheet was poorly known and assumed to have little impact on global sea level rise. The development of regional climate models and remote sensing of the ice sheet during the past decade have revealed a significant mass loss. To monitor how the Greenland Ice Sheet will affect sea levels in the future requires understanding the physical processes that govern its mass balance and movement. In the southeastern and central western regions, mass loss is dominated by the dynamic behaviour of ice streams calving into the ocean. Changes in surface mass balance dominate mass loss from the Greenland Ice Sheet in the central northern, southwestern and northeastern regions. Little is known about what the hydrological system looks like beneath the ice sheet; how well the hydrological system is developed decides the water’s impact on ice movement. In this thesis, I have focused on radar sounding measurements to map the subglacial topography in detail for a land-terminating section of the western Greenland Ice Sheet. This knowledge is a critical prerequisite for any subglacial hydrological modelling. Using the high-resolution ice thickness and bed topography data, I have made the following specific studies: First, I have analysed the geological setting and glaciological history of the region by comparing proglacial and subglacial spectral roughness. Second, I have analysed the subglacial water drainage routing and revealed a potential for subglacial water piracy between adjacent subglacial water catchments with changes in the subglacial water pressure regime. Finally, I have looked in more detail into englacial features that are commonly observed in radar sounding data from western Greenland. In all, the thesis highlights the need not only for accurate high-resolution subglacial digital elevation models, but also for regionally optimised interpolation when conducting detailed hydrological studies of the Greenland Ice Sheet.<br>De ökade temperaturerna i Arktis påskyndar förlusten av landbaserad is lagrad i glaciärer och permafrost. Grönlands inlandsis är den största ismassan på norra halvklotet och lagrar ca 10% av allt sötvatten på jorden, vilket motsvarar ca 7 meter global havsnivåhöjning. För ett par decennier sedan var inlandsisens massbalans dåligt känd och antogs ha liten inverkan på dagens havsnivåhöjning. Utvecklingen av regionala klimatmodeller och satellitbaserad fjärranalys av inlandsisen har under de senaste decenniet påvisat en betydande massförlust. För att förutse vilken inverkan inlandsisen har på framtida havsnivåhöjningar krävs en förståelse för de fysikaliska processerna som styr dess massbalans och isrörelse. I de sydöstra och centrala västra delarna av inlandsisen domineras massförlusten av dynamiska processer i isströmmar som kalvar ut i havet. Massförlusten i de centrala norra, sydvästra och nordöstra delarna domineras av isytans massbalans. Ytterst lite är känt om hur det hydrologiska systemet ser ut under inlandsisen; hur väl det hydrologiska systemet är utvecklat avgör vattnets påverkan på isrörelsen. I denna doktorsavhandling har jag använt markbaserade radarmätningar för att kartlägga den subglaciala topografin för en del av den västra landbaserade inlandsisen. Denna kunskap är en viktig förutsättning för att kunna modellera den subglaciala hydrologin. Med hjälp av rumsligt högupplöst data över istjockleken och bottentopografin har jag gjort följande specifika studier: Först har jag analyserat de geologiska och glaciologiska förhållandena i regionen genom att jämföra proglacial och subglacial spektralanalys av terrängens ytojämnheter. Sedan har jag analyserat den subglaciala vattenavrinningen och påvisat en potential för att avrinningsområdena kan ändras beroende på vattentryckförhållandena på botten. Slutligen har jag tittat mer i detalj på englaciala radarstrukturer som ofta observerats i radardata från västra Grönland. Sammanfattningsvis belyser avhandlingen behovet av inte bara noggranna rumsligt högupplösta subglaciala digitala höjdmodeller, utan även regionalt optimerad interpolering när detaljerade hydrologiska studier ska utföras på Grönlands inlandsis.
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Guillemot, Typhaine. "Réponses sédimentaires et moléculaires des remplissages lacustres groenlandais aux changements climatiques holocènes et à l'évolution des pratiques agropastorales." Thesis, Besançon, 2015. http://www.theses.fr/2015BESA2034/document.
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Dans le cadre du changement climatique global, mieux comprendre les interactions Hommes/Environnement/Climat au sud-ouest du Groenland est aujourd’hui un enjeu majeur pour développer des stratégies d’adaptation tout en préservant au mieux les écosystèmes. Pour cela, une approche rétrospective a été réalisée sur trois séquences lacustres retraçant l’histoire paléo-environnementale sur les 5000 derniers millénaires. Le lac d’Igaliku (N61°00’22’’, O45°26’28’’), situé à 2 km de la capitale épiscopale médiévale au cœur de la région agricole groenlandaise, a une sédimentation principalement influencée par les activités anthropiques. Un inventaire moléculaire complet a été réalisé sur cette séquence pour caractériser les dynamiques agropastorales passées et leurs impacts sur les écosystèmes. Les biomarqueurs fécaux identifié ont notamment permis de mettre en évidence deux phases agropastorales majeures (la période d’occupation viking et la période récente) séparées par le Petit Âge Glaciaire (PAG), pratiquant un élevage prédominant d’ovins. Les biomarqueurs moléculaires de végétation (n-alcanes, acétates de triterpényles) couplées à des données palynologiques montrent une réduction du couvert arbustif au cours de ces deux phases. Par ailleurs, les biomarqueurs d’érosion des sols (TTHCs) couplées aux données sédimentaires indiquent une érosion drastique qu’autour des années 1980 lors de la création de parcelles de fourrage par labour mécanisé. De même, ce n’est que sur le dernier siècle qu’une altération de l’état trophique du lac d’Igaliku associée à des pratiques de fertilisation des parcelles de fourrage est observée avec une augmentation des chaines courtes d’n-alcanes et plus particulièrement des diatomées mésotrophes. Les lacs de Qallimiut (N60°43’27’’, O45°23’12’’) et de Little Kangerluluup (N60°38’32’’, O45°38’11’’), situés en contexte faiblement anthropisé, sont alimentés par des tributaires à forte variabilité hydrologique. Ils correspondent à des systèmes sédimentaires dominés par des apports clastiques sous contrôle climatique dominant. Afin d’améliorer la résolution spatiale et temporelle des changements climatiques holocènes dans cette région, une étude sédimentaire multi-paramètre a été réalisée sur ces deux sites. Des analyses pétrophysiques, granulométriques, minéralogiques et géochimiques ont mis en évidence des niveaux de crues fréquents au cours des épisodes froids et humides comme la transition Milieu/Fin de l’Holocène (ca. 2500 BC), la transition Sub-boréal/Sub-atlantique (ca. 700 BC) et le PAG (entre ca. 1300 AD et ca. 1900 AD), synchrones à des périodes de minimas solaires. Ces épisodes de détériorations climatiques ont particulièrement influencé les sociétés humaines successives installées dès ca. 2500 BC au Groenland. Un maximum de fréquence de crues et une baisse drastique des températures sont notamment enregistrés pendant le PAG, indiquant qu’il s’agit de l’épisode le plus froid enregistré au sud du Groenland au cours de la seconde moitié de l’Holocène, responsable en grande partie de l’abandon de ces terres par les agriculteurs vikings au milieu du XVème siècle<br>In the current context of global change, understanding the interactions between Human/Environment/Climate is necessary to develop adaptive strategies and preserve ecosystems. A retrospective approach is therefore realized in three lacustrine cores to reconstruct the paleo-environmental history during the last five millennia. Lake Igaliku (N61°00’22’’, W45°26’28’’), located at 2km from the medieval episcopal cathedral in the historical farming center, has a sedimentation mainly driven by anthropogenic activities. A complete molecular inventory has been made on this sequence to characterize past agropastoral dynamics and their impacts on south Greenlandic ecosystems. The identified fecal biomarkers revealed two agropastoral phases, during the Norse settlement and recently, separated by the Little Ice Age (LIA) and mainly characterized by sheep breeding. Vegetation molecular biomarkers (n-alkanes, triterpenyl acetates) and palynological data showed a reduction of trees and shrubs cover during these two periods especially. Erosion biomarkers (TTHCs) and sedimentological data identified only one drastic erosion in the 1980s synchronous with the mechanized creation of fodder parcels. Moreover, an eutrophication of the lake waters was recorded with short chain length n-alkanes and mesotrophic diatoms. Lake Qallimiut (N60°43’27’’, W45°23’12’’) and Little Kangerluluup (N60°38’32’’, W45°38’11’’), less impacted by anthropogenic activities, are fed by major streams influenced by hydrological variations. Their sedimentation is therefore mainly driven by climate changes. To improve the temporal and spatial resolution of climate changes during the Holocene, a multi-proxy sedimentological study was made on these two sites. Petrophysical, mineralogical and geochemical analyses have identified flood events especially occurring during cooler and wetter periods such as the Middle to Late Holocene transition (ca. 2500 BC), the Sub-boreal/Sub-atlantic transition (ca. 700 BC) and the LIA (between ca. AD 1300 et ca. AD 1900). These climate pejorations have impacted local human societies. For example, during the LIA, a maximum of flood events and drop of temperatures are recorded, partly responsible of the Norse demise
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Cussans, Julia E. "Changes in the size and shape of domestic mammals across the North Atlantic region over time. The effects of environment and economy on bone growth of livestock from the Neolithic to the Post Medieval period with particular reference to the Scandinavian expansion westwards." Thesis, University of Bradford, 2010. http://hdl.handle.net/10454/5734.
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A large database of domestic mammal bone measurements from sites across Greenland, Iceland, the Faroe Islands, and the Northern and Western Isles of Scotland is presented. The reasons for variations in bone growth of domestic ungulates are examined in detail; nutrition is identified as a key factor in the determination of adult bone size and shape. Possible sources of variation in bone size in both time and space in the North Atlantic region are identified. Four hypotheses are proposed; firstly that bone dimensions, particularly breadth, will decrease with increasing latitude in the study region; secondly that higher status sites will raise larger livestock than lower status sites within the same time period and region; thirdly the size of domestic mammals in the Northern and Western Isles of Scotland will increase in the Later Iron Age, possibly in relation to increased fodder supply; finally at times of environmental degradation (climatic and/or landscape) domestic mammal size will decrease. The latitude hypothesis could only be partly upheld; there is no evidence for increased size with site status; a small increase in size is noted at some Scottish Iron Age sites and varying results are found for the environmental degradation hypothesis. The results are discussed with particular reference to how changes in the skeletal proportions of domestic mammals affect their human carers and beneficiaries. The potential of further expanding the dataset and integrating biometrical data with other forms of evidence to create a powerful tool for the examination of economic and environmental changes at archaeological sites is discussed.<br>The Division of AGES (University of Bradford), the Andy Jagger Fund (University of Bradford), the Francis Raymond Hudson Fund (University of Bradford), the Viking Society, the Prehistoric Society, SYNTHESIS and the Paddy Coker Research Fund (Biogeographical Society)
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Tan, Ning. "Comprendre l’évolution de la cryosphère et du climat du Pliocène à la transition Plio-Pléistocène." Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLV032/document.
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Cette thèse est consacrée à l’étude de l’interaction cryosphère-climat depuis le milieu du Pliocène jusqu’au quaternaire pendant l’installation pérenne de la calotte groenlandaise. Nous étudions d’abord les causes du développement et de la disparition de l’importante mais courte glaciation qui a eu lieu pendant le stade isotopique marin M2 (MIS M23.264-¬3.312 Ma). Ensuite, dans le cadre du programme international sur la modélisation du Pliocène (PLIOMIP2), nous étudions le climat de la période chaude du Plaisancien moyen(MPWP, 3.3-3.0Ma). Enfin, la troisième période étudiée est la transition Plio-Pléistocène transition (PPT, 3.0-2.5Ma), que nous avons étudiée grâce à un couplage asynchrone entre un modèle de climat et un modèle de calotte. A travers ces différentes périodes, nous avons amélioré la connaissance des relations entrepCO2, tectonique et climat pendant la transition d’un monde chaud et riche en CO2 vers le monde bien plus froid et à faible pCO2 des glaciations quaternaires. Ce résultat montre l’importance de mieux comprendre les relations entre dynamique océanique, pCO2 et climat<br>This thesis is devoted tounderstanding the interaction betweencryosphere and climate from the mid Plioceneto the early Quaternary during the onset ofNorthern Hemisphere Glaciation (NHG).Firstly, we investigate the causes for thedevelopment and decay of the large but shortliving glaciation that occurred during MarineIsotope Stage 2 (M2, 3.264-¬3.312 Ma);Secondly, in the framework of the internationalPliocene Model Intercomparison Project(PLIOMIP2), we study the climate of Mid-Piacenzian Warm Period (MPWP, 3.3-3.0Ma).Thirdly, we explore the Plio-PleistoceneTransition (PPT, 3.0-2.5Ma) with anappropriate asynchronously coupled climatecryosphere model. Through these differentperiods, we provide a better understanding ofthe relationship between pCO2, tectonics andclimat during the transition from a warm andhigh-CO2 world to the cold and low-CO2Quaternary glaciations. This work also pointsout the necessity to further study the linkbetween ocean dynamics, carbon cycle andclimate
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Cussans, Julia Elise. "Changes in the size and shape of domestic mammals across the North Atlantic region over time : the effects of environment and economy on bone growth of livestock from the Neolithic to the post-medieval period, with particular reference to the Scandinavian expansion westwards." Thesis, University of Bradford, 2010. http://hdl.handle.net/10454/5734.
Full textAbstract:
A large database of domestic mammal bone measurements from sites across Greenland, Iceland, the Faroe Islands, and the Northern and Western Isles of Scotland is presented. The reasons for variations in bone growth of domestic ungulates are examined in detail; nutrition is identified as a key factor in the determination of adult bone size and shape. Possible sources of variation in bone size in both time and space in the North Atlantic region are identified. Four hypotheses are proposed; firstly that bone dimensions, particularly breadth, will decrease with increasing latitude in the study region; secondly that higher status sites will raise larger livestock than lower status sites within the same time period and region; thirdly the size of domestic mammals in the Northern and Western Isles of Scotland will increase in the Later Iron Age, possibly in relation to increased fodder supply; finally at times of environmental degradation (climatic and/or landscape) domestic mammal size will decrease. The latitude hypothesis could only be partly upheld; there is no evidence for increased size with site status; a small increase in size is noted at some Scottish Iron Age sites and varying results are found for the environmental degradation hypothesis. The results are discussed with particular reference to how changes in the skeletal proportions of domestic mammals affect their human carers and beneficiaries. The potential of further expanding the dataset and integrating biometrical data with other forms of evidence to create a powerful tool for the examination of economic and environmental changes at archaeological sites is discussed.
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Veitch, Stephen Alexander. "Glacial Earthquakes and Glacier Seismicity in Greenland." Thesis, 2016. https://doi.org/10.7916/D8J1035T.
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The loss of ice from the Greenland ice sheet is an important contributor to current and future sea level rise occurring due to ongoing changes in the global climate. A significant portion of this ice mass loss comes through the calving of large icebergs at Greenland’s many marine-terminating outlet glaciers. However, the dynamics of calving at these glaciers is currently not well understood, complicating projections of future behaviour of these glaciers and mass loss from the Greenland ice sheet. The use of seismological tools has shown promise as a means of both monitoring and better understanding the dynamics of the calving process at these glaciers. On the global scale, data from the long-standing global seismic network has recorded the occurrence of glacial earthquakes, large long period earthquakes that occur during large calving events at near-grounded outlet glaciers. The occurrence and source parameters of these earthquakes provide insight into the link between glacier calving and climatic and oceanic forcings, as well as information on the large-scale glacier-dynamic conditions under which these major calving events occur. On the more local scale, a deployment of seismometers around an individual glacier has provided insights on the seismic environment of a calving glacier, as well as the more immediate, short-term external drivers of calving events. We consider both local and global seismic data in order to further understanding of the dynamics of the calving process at Greenland outlet glaciers, and find that glacial earthquake production is indicative of a near-grounded terminus at the source glacier. We find that the locations derived from these events are accurate and are sensitive to changes in the calving-front position of the source glacier, and that the active-force azimuths are representative of the orientation of the glacier at the time of calving. We also find that these glaciers are the source of abundant small icequakes, which are strongly tied to the occurrence of major calving events. The small icequakes that occur at Helheim glacier are modulated by semi-diurnal variations in tide height, and potentially control the timing of major calving events by progressively damaging the glacier tongue.
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Chu, Wing Yin. "Variability of Subglacial Drainage Across the Greenland Ice Sheet: A Joint Model/Radar Study." Thesis, 2017. https://doi.org/10.7916/D8348XSV.
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Over the last several decades, the majority of the Greenland outlet glaciers have accelerated due to the increased warming in both the atmosphere and the oceans around the polar latitudes. While there is a clear overall acceleration trend over this period, there is significant variability in the glacier responses to climate on seasonal and year-to-year timescales. This variability observed around Greenland is very likely tied to the differences in internal dynamics of individual glaciers and the complex interaction with its local environment. Here I investigate the interaction between ice and water along the ice base as an important mechanism contributing to the observed variability among glaciers in Greenland. I use a range of modeling and radar sounding approaches to study the subglacial hydrology for three types of outlet glaciers, including slow moving, marine terminating glaciers in the west, a land-terminating system in the southwest, and a fast moving, marine-terminating glacier in northern Greenland. These case studies allow me to characterize the basal water distribution, its variability throughout the year and how this drainage behavior varies across different regions of Greenland.
To start, I use a hydrological routing model to characterize the subglacial hydrology for three neighboring slow moving (< 100myr−1), marine terminating glaciers in western Greenland. The hydrologic model allows me to examine the sensitivity of basal water routing to subtle changes in basal water pressures. My results reveal that Greenland subglacial drainage can be rerouted across 100’s of km in response to changes in basal water pressures as small as 10%. I conclude that water piracy and subsequent dramatic changes in ice velocity, similar to that observed around the Siple Coast in West Antarctica, can occur in Greenland. Next, I move to a more data-orientated approach and use airborne radar sounding to examine the seasonal variability of basal water distribution. To robustly characterize basal water from radar bed power, I use a novel radar analysis approach that integrates a thermomechanical ice-sheet model to predict the spatial variations of radar attenuation. I improve this approach by including a least-squares minimization to correct for power offsets due to the different radar systems deployed in multiple field seasons.
This improved method is first applied to two land-terminating glaciers in the southwest, Russell Glacier, and Isunnguata Sermia. Using two seasons of radar sounding data, I find that the basal water distribution can change between the wintertime and the summertime. My results reveal that during the winter, water resides primarily in small pockets on top of bedrock ridges. In the summer, these pockets of water on the ridges connect and drain into the nearby basal troughs. This seasonal shift in the basal water distribution is actively controlled by the material properties of the bed. Therefore, in addition to the bed topography, the permeability of the bed and the presence of basal sediments could also exert a critical influence on the seasonal development of subglacial drainage.
Finally, I apply the radar analysis approach to a fast-flowing marine terminating glacier for Petermann Glacier in Northern Greenland. Here I incorporate an additional step to address the spatial variation in ice chemistry and its effect on radar attenuation. I use this approach to examine the relationship between basal water, ice deformation and the onset of glacier flow. In addition to finding basal water in the fastest flowing region near the ice margin, I identify substantial basal water in the ice sheet interior where meltwater must either be related to the advection of water from upstream or be generated by internal heating due to ice deformation. My results show there are three basal water networks beneath Petermann that connect the ice sheet interior to the margin. Together, the interaction between these basal water networks and the ice deformation enhances and sustains fast flow in the interior of the Petermann catchment. Overall, the research presented in this dissertation suggests that subglacial hydrology is high variable in both space and time. This variation in the hydrologic system can influence the fundamental structure of the ice sheet through changing the transport and storage of basal water and through interacting with ice deformation and the thermal properties of the bed.
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Koenig, Sebastian Jan. "Greenland ice sheet variability and sensitivity to forcing during the warm Pliocene A numerical modeling study." 2012. https://scholarworks.umass.edu/dissertations/AAI3498351.
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The cryosphere and its interactions with other components of the climate system are considered to be major influences on global climate change through the Cenozoic and into the future. However, fundamental dynamics and secondary feedbacks that drive long-term ice sheet variability on Greenland remain poorly understood. Here, a numerical climate-ice sheet modeling study is conducted with the aim of reconstructing most likely locations, timing and variability of continental ice in the mid to late Pliocene and the transition into the Pleistocene. Simulations using the GENESIS v3 General Circulation Model coupled to the Penn State Ice Sheet-Shelf Model are compared with a range of independent numerical ice sheet model simulations under Pliocene boundary conditions and validated against available proxy reconstructions. This study aims at investigating the sensitivity of an ice-free and glaciated Greenland to changes in climate forcings, and the modulation of those forcings through internal feedbacks with focus on the dynamical thresholds involved in the growth and retreat of continental ice on Greenland. Orbital changes of latitudinal and seasonal solar radiation, in combination with prevalent atmospheric pCO2 levels, are found to pace the timing of the cryospheric response. Internal feedbacks invoked though local surface characteristics on Greenland in concert with far field changes in Arctic sea surface temperature and sea ice conditions control the energy and moisture budget on Greenland with consequences for its mass balance. In the Pliocene, inception of Greenland ice is inhibited during interglacials and ice volume is limited even when orbits are favorable for ice sheet growth. During Pliocene warmth, a present-day Greenland Ice Sheet cannot be maintained and ice was most likely restricted to the highest elevations in the East and South, contributing ∼6m of equivalent sea level rise. This assessment of the sensitivity and survivability of Greenland Ice Sheet in a warmer-than-modern world implies the potential for a long-term commitment to future sea level rise from a smaller Greenland Ice Sheet.
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Steeves, Holly. "Non-Parametric Statistical Tests for Differences in Fatty Acid Composition of Greenland Sharks." 2013. http://hdl.handle.net/10222/42657.
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Variations in predator diets is important in ecology to help us understand their top-down effects on the ecosystem. In predator diets, their fatty acid signatures reflect the proportions of prey consumed. Since fatty acid signatures are compositional and often longer than the sample size, a standard MANOVA test is unsuitable. Here, non-parametric MANOVA techniques are developed to test for differences in fatty acid signatures among locations, years, and seasons which infer differences in diets. Simulations show that the test has good power and appropriate type I error rates. The tests developed were applied to data on Greenland Sharks to test for differences in diets between individuals from Cumberland Sound, Canada, versus those from Svalbard, Norway and whether there is a yearly and/or seasonal effect on the diets. Diet compositions were found to vary between the locations, seasons and years, possibly caused by differing prey species distributions, migrations, and climate change.
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Robinson, Alexander [Verfasser]. "Modeling the Greenland ice sheet response to climate change in the past and future / vorgelegt von Alexander Robinson." 2011. http://d-nb.info/1013214315/34.
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Charalampidis, Charalampos. "Climatology and firn processes in the lower accumulation area of the Greenland ice sheet." Doctoral thesis, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-284365.
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The Greenland ice sheet is the largest Northern Hemisphere store of fresh water, and it is responding rapidly to the warming climate. In situ observations document the changing ice sheet properties in the lower accumulation area, Southwest Greenland. Firn densities from 1840 meters above sea level retrieved in May 2012 revealed the existence of a 5.5-meter-thick, near-surface ice layer in response to the recent increased melt and refreezing in firn. As a consequence, vertical meltwater percolation in the extreme summer 2012 was inefficient, resulting in surface runoff. Meltwater percolated and refroze at six meters depth only after the end of the melt season. This prolonged autumn refreezing under the newly accumulated snowpack resulted in unprecedented firn warming with temperature at ten meters depth increased by more than four degrees Celsius. Simulations confirm that meltwater reached nine meters depth at most. The refrozen meltwater was estimated at 0.23 meters water equivalent, amounting to 25 % of the total 2012 ablation. A surface energy balance model was used to evaluate the seasonal and interannual variability of all surface energy fluxes at that elevation in the years 2009 to 2013. Due to the meltwater presence at the surface in 2012, the summer-averaged albedo was significantly reduced (0.71 in 2012; typically 0.78). A sensitivity analysis revealed that 71 % of the subsequent additional solar radiation in 2012 was used for melt, corresponding to 36 % of the total 2012 surface lowering. This interplay between melt and firn properties highlights that the lower accumulation area of the Greenland ice sheet will be responding rapidly in a warming climate.<br>Stability and Variations of Arctic Land Ice (SVALI)<br>Programme for Monitoring of the Greenland Ice Sheet (PROMICE)<br>Greenland Analogue Project (GAP)
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"What climate change for the 21st century ? A projection with LMD5-CLIO2 and its sensitivity to freshwater flux from the Greenland ice sheet." Université catholique de Louvain, 2003. http://edoc.bib.ucl.ac.be:81/ETD-db/collection/available/BelnUcetd-08162003-120351/.
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