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Estimating Bedrock Fracture Density Of The Juneau Icefield, Ak, To Inform Glacial Erosion Models, Colby Rand

Honors College

Understanding glacial erosion rates is important because debris eroded by a glacier can impact glacier flow speeds, protect tidewater glaciers from rapid retreat, and impact the productivity of marine ecosystems. Traditionally, glacial erosion models rely on a rock’s inherent “erodibility”, typically presented as a constant, to predict how much debris will be eroded by the glacier. However, the erodibility of bedrock varies spatially as a function of its fracture density, fracture orientation, and lithology, so the notion of applying a constant erodibility term to a whole field site does not fully capture the actual bedrock dynamics of the system. In …

The Microstructural Heterogeneity Of Ice In Jarvis Glacier, Alaska, Renée Clavette

Honors College

Glacier ice behaves as a viscous fluid, where flow is controlled by a number of external and internal processes. One crucial, yet sometimes overlooked, factor is ice microstructure. Studies have shown that ice crystal (grain) size, shape, and orientation influence the viscous strength of ice, and therefore its resistance to flow and deformation. Glacier flow is also impacted by friction at the bed and lateral margins. The magnitude of flow resistance due to the lateral margins is not well quantified. The goal of this overall project is to evaluate how heterogeneous optical properties of ice are that are influenced by …

Remote Sensing Of Icebergs In Greenland's Fjords And Coastal Waters, Jessica Scheick

Electronic Theses and Dissertations

Increases in ocean water temperature are implicated in driving recent accelerated rates of mass loss from the Greenland Ice Sheet. Icebergs provide a key tool for gaining insight into ice-ocean interactions and until recently have been relatively understudied. Here we develop several methods that exploit icebergs visible in optical satellite imagery to provide insight on the ice--ocean environment and explore how iceberg datasets can be used to examine the physics of iceberg decay and parent glacier properties. First, a semi-automated algorithm, which includes a machine learning-based cloud mask, is applied to six years (2000-2002 and 2013-2015) of the Landsat archive …

Increasing The Resolution Of The Last Glacial Maximum Record In The Tropical Andes Using 10be Cosmogenic Surface-Exposure Dating In The Cordillera Carabaya, Peru, Zachary E. Mason

Honors College

Owing to the abundance of heat and moisture, the tropics is a fundamental component of the global climate system. Yet the role of the tropics in climate remains poorly understood. The Andes are home to ~95% of all tropical glaciers, making this the ideal region for studying relationships between tropical glaciers and climate. I conducted a Beryllium-10 surface exposure dating experiment using ten quartz-bearing rock samples from a series of last glacial maximum (LGM) moraines in the Minas Tira glaciofluvial valley system, Cordillera Carabaya, Peru. The AMS measured sample dates (excluding outliers) range from 24.3 ± 0.5 ka to 19.4 …

Roosevelt Island Climate Evolution Project (Rice): Us Deep Ice Core Glaciochemistry Contribution (2011- 2014), Paul Andrew Mayewski, Karl J. Kreutz, Andrei V. Kurbatov

University of Maine Office of Research Administration: Grant Reports

This award supports a project to analyze a deep ice core which will be drilled by a New Zealand research team at Roosevelt Island. The objectives are to process the ice core at very high resolution to (a) better understand phasing sequences in Arctic/Antarctic abrupt climate change, even at the level of individual storm events; (b) determine the impact of changes in the Westerlies and the Amundsen Sea Low on past/present/future climate change; (c) determine how sea ice extent has varied in the area; (d) compare the response of West Antarctica climate to other regions during glacial/interglacial cycles; and (e) …

Collaborative Research: Timing And Structure Of The Last Glacial Maximum And Termination In Southern Peru: Implications For The Role Of The Tropics In Climate Change, Brenda L. Hall

University of Maine Office of Research Administration: Grant Reports

The role of the tropics in climate change has important implications for understanding both orbital-scale and abrupt climate variations. Yet our ability to assess tropical behavior during major climate events, such as the last glacial maximum (LGM), is limited by poor spatial coverage and insufficient control on sample ages. This project will address this problem by developing well-dated records of glacial fluctuations from the LGM through the termination and late-glacial period at Nevados Coropuna and Allinccapac in southern Peru and use these data in numerical simulations of glacier mass balance and local climate. These sites allow an examination of glacier …

Sensitivity Of The Antarctic Ice Sheet To Climate Change Over The Last Two Glacial/Interglacial Cycles, Brenda Hall, George H. Denton

University of Maine Office of Research Administration: Grant Reports

This project was designed to develop knowledge of the extent of the Ross Sea ice sheet during the last two glaciations and to develop a chronology for the last glacial maximum and penultimate glaciation. To this end, we had the following goals:

1) Map the extent of the Ross Sea ice sheet along the western coast of McMurdo Sound from Taylor Valley to the southern Royal Society Range.
2) Develop a radiocarbon chronology for the last glacial maximum from dates of algal mats within moraines.
3) Produce a uranium-thorium chronology to gain information on the timing of the penultimate glaciation. …

Colle Gnifetti Ice Core (Kcc) Progress Report (Year One)—Arcadia Ice Core Proposal: Initiatives On The Science Of The Human Past, Paul Mayewski

University of Maine Office of Research Administration: Grant Reports

The Colle Gnifetti glacier of the Monta Rosa Massif on the Swiss-Italian border is perfectly situated to offer insight into the intersection of environment (climate) and culture (history of the economy, political stability, pollution, disease) in medieval Europe. While ice cores previously collected at Colle Gnifetti were sampled at state-of-the-art resolution for the time, it was nevertheless impossible to differentiate annual or finer layering in the period older than 1500 A.D. The 2013 Colle Gnifetti expedition thus sought to collect a new ice core that could be analyzed using the ultra-high-resolution laser based technology developed in the Climate Change Institute’s …

Collaborative Research: Subglacial Water Intrusion In Greenland, Gordon K. Oswald

University of Maine Office of Research Administration: Grant Reports

The project's goals are:

• To analyse radio echo sounding data acquired over the Greenland Ice Sheet by the University of Kansas / CReSIS team with the objective of discriminating between frozen and thawed conditions at the bed of the ice sheet.
• To provide maps of the bed state, with the aim of making them available via the National Snow and Ice Data Centre.
• To support ice sheet modelling activities by providing information on the bed state, thus related to the temperature at the bed and the rheological conditions at the bed.
• To make available to educational establishments information on the …

Antarctic Climate Change And The Environment, Peter Convey, R. Bindschadler, G. Di Prisco, E. Fahrbach, J. Gutt, D. A. Hodgson, Paul Andrew Mayewski, C. P. Summerhayes, J. Turner, Acce Consortium

Earth Science Faculty Scholarship

The Antarctic climate system varies on timescales from orbital, through millennial to sub-annual, and is closely coupled to other parts of the global climate system. We review these variations from the perspective of the geological and glaciological records and the recent historical period from which we have instrumental data (similar to the last 50 years). We consider their consequences for the biosphere, and show how the latest numerical models project changes into the future, taking into account human actions in the form of the release of greenhouse gases and chlorofluorocarbons into the atmosphere. In doing so, we provide an essential …

State Of The Antarctic And Southern Ocean Climate System, Paul Andrew Mayewski, M. P. Meredith, C. P. Summerhayes, J. Turner, A. Worby, P. J. Barrett, G. Casassa, Nancy Bertler, T. Bracegirdle, A. C. Naveira Garabato, D. Bromwich, H. Campbell, Gordon S. Hamilton, W. B. Lyons, Kirk A. Maasch, S. Aoki, C. Xiao, Tas Van Ommen

Earth Science Faculty Scholarship

This paper reviews developments in our understanding of the state of the Antarctic and Southern Ocean climate and its relation to the global climate system over the last few millennia. Climate over this and earlier periods has not been stable, as evidenced by the occurrence of abrupt changes in atmospheric circulation and temperature recorded in Antarctic ice core proxies for past climate. Two of the most prominent abrupt climate change events are characterized by intensification of the circumpolar westerlies (also known as the Southern Annular Mode) between ∼6000 and 5000 years ago and since 1200–1000 years ago. Following the last …

Ice Core Record Of Rising Lead Pollution In The North Pacific Atmosphere, E. Osterberg, Paul Andrew Mayewski, Karl J. Kreutz, D. Fisher, Michael Handley, Sharon Sneed, C. Zdanowicz, J. Zheng, M. Demuth, M. Waskiewicz, J. Bourgeois

Earth Science Faculty Scholarship

A high-resolution, 8000 year-long ice core record from the Mt. Logan summit plateau (5300 m asl) reveals the initiation of trans-Pacific lead (Pb) pollution by ca. 1730, and a >10-fold increase in Pb concentration (1981–1998 mean = 68.9 ng/l) above natural background (5.6 ng/l) attributed to rising anthropogenic Pb emissions from Asia. The largest rise in North Pacific Pb pollution from 1970–1998 (end of record) is contemporaneous with a decrease in Eurasian and North American Pb pollution as documented in ice core records from Greenland, Devon Island, and the European Alps. The distinct Pb pollution history in the North Pacific …

Calving Giant Icebergs: Old Principles, New Applications, James P. Kenneally, Terence J. Huges

Earth Science Faculty Scholarship

Earth-orbiting satellites can now monitor calving of large icebergs from ice shelves bordering the marine West Antarctic Ice Sheet, and recent calving events have stimulated interest in calving mechanisms. To advance this interest pioneering work in brittle and ductile fracture mechanics is reviewed, leading to a new application to calving of giant icebergs from Antarctic ice shelves. The aim is to view iceberg calving as more than terminal events for Antarctic ice when glaciologists lose interest. Instead calving launches Antarctic ice into the larger dynamic system of Earth's climate machine. This encourages a holistic approach to glaciology.

Snow Chemistry Across Antarctica, Nancy Bertler, Paul Andrew Mayewski, Alberto Aristarain, P. Barrett, S. Becagli, Ronaldo Torma Bernardo, Xiao Cunde, M. Curran, Qin Dahe, Daniel Dixon, Francisco Adolfo Ferron, H. Fischer, Markus Frey, M. Frezzotti, F. Fundel, Christophe Genthon, R. Gragani, Gordon Hamilton, M. Handley, Sungmin Hong, E. Isaksson, Ren Jiawen, Kokichi Kamiyama, Satoru Kanamori, Eija Karkas, L. Karlöf, S. Kaspari, K. Kreutz, A. Kurbatov, E. Meyerson, Hideaki Motoyama, R. Mulvaney, Zhang Mingjun, H. Oerter, E. Osterberg, M. Proposito, A. Pyne, U. Ruth, Jefferson Cardia Simoes, B. Smith, S. Sneed, Kimmo Teinila, F. Traufetter, R. Udisti, Aki Virkkula, Okitsugu Watanabe, B. Williamson, E. Wolff, Li Zhongqin

Earth Science Faculty Scholarship

An updated compilation of published and new data of major-ion (Ca, Cl, K, Mg, Na, NO₃, SO₄) and methylsulfonate (MS) concentrations in snow from 520 Antarctic sites is provided by the national ITASE (International Trans-Antarctic Scientific Expedition) programmes of Australia, Brazil, China, Germany, Italy, Japan, Korea, New Zealand, Norway, the United Kingdom, the United States and the national Antarctic programme of Finland. The comparison shows that snow chemistry concentrations vary by up to four orders of magnitude across Antarctica and exhibit distinct geographical patterns. The Antarctic-wide comparison of glaciochemical records provides a unique opportunity to improve …

The International Trans-Arctic Scientific Expedition (Itase): An Overview, Paul Andrew Mayewski, Massimo Frezzotti, Nancy Bertler, Tas Van Ommen, Gordon S. Hamilton, Tim H. Jacka, Brian Welch, Markus Frey, Dahe Qin, Jiawen Ren, Jefferson Simões, Michel Fily, Hans Oerter, Fumihiko Nishio, Elisabeth Isaksson, Robert Mulvaney, Per Holmund, Volodya Lipenkov, Ian Goodwin

Earth Science Faculty Scholarship

From its original formulation in 1990 the International Trans-Antarctic Scientific Expedition (ITASE) has had as its primary aim the collection and interpretation of a continent-wide array of environmental parameters assembled through the coordinated efforts of scientists from several nations. ITASE offers the ground-based opportunities of traditional-style traverse travel coupled with the modern technology of GPS, crevasse detecting radar, satellite communications and multidisciplinary research. By operating predominantly in the mode of an oversnow traverse, ITASE offers scientists the opportunity to experience the dynamic range of the Antarctic environment. ITASE also offers an important interactive venue for research similar to that afforded …

Fracture And Back Stress Along The Byrd Glacier Flowband On The Ross Ice Shelf, James P. Kenneally, Terence J. Hughes

Earth Science Faculty Scholarship

East Antarctic ice discharged by Byrd Glacier continues as a flowband to the calving front of the Ross Ice Shelf. Flow across the grounding line changes from compressive to extensive as it leaves the fjord through the Transantarctic Mountains occupied by Byrd Glacier. Magnitudes of the longitudinal compressive stress that suppress opening of transverse tensile cracks are calculated for the flowband. As compressive back stresses diminish, initial depths and subsequent growth of these cracks, and their spacing, are calculated using theories of elastic and ductile fracture mechanics. Cracks are initially about one millimeter wide, with approximately 30 in depths and …

El Niño Suppresses Antarctic Warming, Nancy A. N. Bertler, Peter J. Barrett, Paul Andrew Mayewski, Ryan L. Fogt, Karl J. Kreutz, James Shulmeister

Earth Science Faculty Scholarship

Here we present new isotope records derived from snow samples from the McMurdo Dry Valleys, Antarctica and re-analysis data of the European Centre for Medium-Range Weather Forecasts (ERA-40) to explain the connection between the warming of the Pacific sector of the Southern Ocean [Jacka and Budd, 1998; Jacobs et al., 2002] and the current cooling of the terrestrial Ross Sea region [Doran et al., 2002a]. Our analysis confirms previous findings that the warming is linked to the El Niño Southern Oscillation (ENSO) [Kwok and Comiso, 2002a, 2002b; Carleton, 2003; Ribera and Mann …

Variability In Accumulation Rates From Gpr Profiling On The West Antarctic Plateau, Vandy B. Spikes, Gordon S. Hamilton, Steven A. Arcone, Susan Kaspari, Paul Andrew Mayewski

Earth Science Faculty Scholarship

Isochronal layers in firn detected with ground-penetrating radar (GPR) and dated using results from ice-core analyses are used to calculate accumulation rates along a 100 km across-flow profile in West Antarctica. Accumulation rates are shown to be highly variable over short distances. Elevation measurements from global positioning system surveys show that accumulation rates derived from shallow horizons correlate well with surface undulations, which implies that wind redistribution of snow is the leading cause of this variability. Temporal changes in accumulation rate over 25-185 year intervals are smoothed to along-track length scales comparable to surface undulations in order to identify trends …

Geometrical Force Balance In Glaciology, Terence J. Hughes

Earth Science Faculty Scholarship

The analytical force balance traditionally used in glaciology relates gravitational forcing to ice surface slope for sheet flow and to ice basal buoyancy for shelf flow. It is unable to represent stream flow as a transition from sheet flow to shelf flow by having gravitational forcing gradually passing from being driven by surface slope to being driven by basal buoyancy downslope along the length of an ice steam. This is a serious defect, because ice streams discharge up to 90% of ice from ice sheets into the sea. The defect is overcome by using a geometrical force balance that includes …

Antarctic Oversnow Traverse-Based Southern Hemisphere Climate Reconstruction, Paul Andrew Mayewski

Earth Science Faculty Scholarship

On 2 January 2003, the U.S. component of the International Trans Antarctic Scientific Expedition (U.S. ITASE) (Figure 1) arrived at the South Pole after completing more than 5000 km of oversnow traverses that included much of west Antarctica and a portion of east Antarctica (Figure 2). During the traverses, which were performed from 1999 through 2003, U.S. ITASE focused on collecting data that will allow the reconstruction of sub-annual scale climate variability and changes in the chemistry of the atmosphere over the last 200+ years.

ITASE is a multi-disciplinary research program supported by 19 nations and endorsed by the Scientific …

Chemical Composition Of Fresh Snow On Xixabangma Peak, Central Himalaya, During The Summer Monsoon Season, Shichang Kang, Dahe Qin, Paul Andrew Mayewski, Sharon B. Sneed

Earth Science Faculty Scholarship

The physical and chemical analysis of ice cores recovered from glaciers in the Himalaya provide some of the best records of past climate change in the region (e.g. Qin and others, 2000; Thompson and others, 2000; Kang and others, 2001, 2002). In order to better understand the climatic and environmental records preserved in snow and ice, studies have investigated the precipitation chemistry in the high Himalaya, notably that the northern slopes of the central Himalaya (Mayewski and others, 1986; Jenkins and others 1987) and the southern slopes of the central Himalaya (Shrestha and others, 1997; Marinoni and others, 2001).

Methanesulfonate In The Firn Of King George Island, Antarctica, Jiankang Han, Zichu Xie, Xinping Zhang, Dongsheng Dai, Paul Andrew Mayewski, M. S. Twickler

Earth Science Faculty Scholarship

Methanesulfonate was investigated as a potential contributor to the sulfur budget, based on analysis of a firn core from Collins Ice Cap, King George Island, Antarctica (62°10' S, 58°50' W). The anion was found to be present at a mean concentration of 0.17 μeq L^-1, with a maximum of 0.73 μeq L^-1. Dating based on the δ¹⁸O profile suggests that the principal peaks of methanesulfonate are associated with snow deposited in summer and autumn. A careful examination of MSA, SO₄^2-and nssSO₄^2- profiles indicates that two of the three peaks …

High-Precision Dating Of Volcanic Events (A.D. 1301–1995) Using Ice Cores From Law Dome, Antarctica, Anne S. Palmer, Tas D. Van Ommen, Mark A. J. Curran, Vin Morgan, Joe M. Souney, Paul Andrew Mayewski

Earth Science Faculty Scholarship

A record of volcanic activity over the period A.D. 1301–1995 has been extracted from three Law Dome ice cores (East Antarctica). The record dating is unambiguous at the annual level from A.D. 1807 to 1995 and has an uncertainty of ±1 year at A.D. 1301. Signals from 20 eruptions are preserved in the record, including those of two unknown eruptions with acid deposition beginning in A.D. 1810.8 and A.D. 1685.8. The beginning of the ice core signal from the A.D. 1815 Tambora eruption is observed in the austral summer of A.D. 1816/1817. The mean observed stratospheric transport and deposition time …

The Effect Of Spatial And Temporal Accumulation Rate Variability In West Antarctica On Soluble Ion Deposition, K. J. Kreutz, Paul Andrew Mayewski, L. D. Meeker, M. S. Twickler, S. I. Whitlow

Earth Science Faculty Scholarship

Annually‐dated snowpit and ice core records from two areas of West Antarctica are used to investigate spatial accumulation patterns and to evaluate temporal accumulation rate/glaciochemical concentration and flux relationships. Mean accumulation rate gradients in Marie Byrd Land (11–23 gcm⁻²yr⁻¹ over 150 km, decreasing to the south) and Siple Dome (10–18 gcm⁻²yr⁻¹ over 60 km, decreasing to the south) are consistent for at least the last several decades, and demonstrate the influence of the offshore quasi‐permanent Amundsen Sea low pressure system on moisture flux into the region. Local and regional‐scale topography in both regions appears …

Sea Level Pressure Variability In The Amundsen Sea Region Inferred From A West Antarctic Glaciochemical Record, K. J. Kreutz, Paul Andrew Mayewski, I. I. Pittalwala, L. D. Meeker, M. S. Twickler, S. I. Whitlow

Earth Science Faculty Scholarship

Using European Center for Medium-Range Weather Forecasts (ECMWF) numerical operational analyses, sea ice extent records, and station pressure data, we investigate the influence of sea level pressure variability in the Amundsen Sea region on a West Antarctic (Siple Dome) glaciochemical record. Empirical orthogonal function analysis of the high-resolution Siple Dome multivariate ice core chemical time series record (SDEOF1) documents lower tropospheric transport of sea-salt aerosols to the site. During 1985–1994 the SDEOF1 record of high (low) aerosol transport corresponds to anomalously low (high) sea level pressure (SLP) in the Amundsen Sea region. Spatial correlation patterns between ECMWF monthly SLP fields …

Evidence For Recent Climate Change From Ice Cores In The Central Himalaya, Qin Dahe, Paul Andrew Mayewski, Cameron P. Wake, Kang Shichang, Ren Jiawen, Hou Shugui, Yao Tandong, Yang Qinzhao, Jin Zhefan, Mi Desheng

Earth Science Faculty Scholarship

Comparison of the terminus locations of Rongbuk Glacier, Mount Everest, measured in 1966 and 1997 shows that in the past 30 years the glacier has retreated 170-270 m, equivalent to a retreat speed of 5.5-8.7 m a⁻¹. During summer 1997, a 15 m firn core was recovered from Dasuopu glacier (28°23′N, 85°44′E; 7000 m a.s.l.) on the northwest margin of Xixabangma Feng, Xizang (Tibet). The seasonal variations of δ¹⁸O values in the core indicate that monsoon signals are clearly recorded in the glacier. δ¹⁸O values are controlled by the amount effect in the monsoon …

Monsoon And Dust Signals Recorded In Dasuopu Glacier, Tibetan Plateau, Kang Shichang, Cameron P. Wake, Qin Dahe, Paul Andrew Mayewski, Yao Tandong

Earth Science Faculty Scholarship

During summer 1997, a 15m firn core was recovered from Dasuopu glacier (28°23'N, 85° 44' E; 7000 m a.s.l.) on the northwest margin of Xixabangma Feng in the central Himalaya. Oxygen isotope values and concentrations of Ca²⁺, Mg²⁺, NH₄⁺, SO₄^2- and NO₃^- were measured over the 10 years of snow accumulation captured in the firn core. The seasonal variations of δ¹⁸O values and major-ion concentrations in the Dasuopu core indicated that summer monsoon and dust signals are clearly recorded in Dasuopu glacier. Annual variations in the δ …

Maximum Temperature Trends In The Himalaya And Its Vicinity: An Analysis Based On Temperature Records From Nepal For The Period 1971-94, Arun B. Shrestha, Camerson P. Wake, Paul Andrew Mayewski, Jack E. Dibb

Earth Science Faculty Scholarship

Analyses of maximum temperature data from 49 stations in Nepal for the period 1971-94 reveal warming trends after 1977 ranging from 0.06° to 0.12°C yr¹ in most of the Middle Mountain and Himalayan regions, while the Siwalik and Terai (southern plains) regions show warming trends less than 0.03°C yr¹. The subset of records (14 stations) extending back to the early 1960s suggests that the recent warming trends were preceded by similar widespread cooling trends. Distributions of seasonal and annual temperature trends show high rates of warming in the high-elevation regions of the country (Middle Mountains and Himalaya), …

Antarctic's Role Pursued In Global Climate Change, Paul Andrew Mayewski, I. Goodwin

Earth Science Faculty Scholarship

The impact of Antarctica on global climate change and the impact of global climate change on Antarctica are the focal points of a current series of expeditions there, and an international, interdisciplinary array of researchers met this past spring to go over the expeditions' progress. Advances were reported in describing the impact of the seasonal cycle, semiannual oscillation, and the El Niño-Southern Oscillation (ENSO) cycle on Antarctic accumulation in recent decades.

Difficulties still remain, however, in explaining fully the history and forcing of the Antarctic climate and the links between tropical forcing and high-latitude response. The difficulties arise largely because …

Spatial Variability Of Climate And Past Atmospheric Circulation Patterns From Central West Antarctic Glaciochemistry, David B. Reusch, Paul Andrew Mayewski, Sallie I. Whitlow, Iqbal I. Pittalawa, Mark S. Twickler

Earth Science Faculty Scholarship

Atmospheric circulation patterns and the spatial variability of atmospheric chemistry and moisture transport in central West Antarctica are investigated using new 40 year long (1954–1994 A.D.) glaciochemical and accumulation rate records developed from four firn cores from this region. The core sites lie on a 200 km traverse from 82° 22′ S, 119° 17′ W to 81° 22′ S, 107° 17′ W. The glaciochemical records represent the major ionic species present in Antarctic snow: Na⁺, K⁺, Mg²⁺, Ca²⁺, Cl⁻, NO₃⁻, and SO₄²⁻. High spatial …