Changes in Glacier Facies Zonation on Devon Ice Cap, Nunavut, Detected
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Lecture 21: Glaciers and Paleoclimate Read: Chapter 15 Homework Due Thursday Nov
Learning Objectives (LO) Lecture 21: Glaciers and Paleoclimate Read: Chapter 15 Homework due Thursday Nov. 12 What we’ll learn today:! 1. 1. Glaciers and where they occur! 2. 2. Compare depositional and erosional features of glaciers! 3. 3. Earth-Sun orbital parameters, relevance to interglacial periods ! A glacier is a river of ice. Glaciers can range in size from: 100s of m (mountain glaciers) to 100s of km (continental ice sheets) Most glaciers are 1000s to 100,000s of years old! The Snowline is the lowest elevation of a perennial (2 yrs) snow field. Glaciers can only form above the snowline, where snow does not completely melt in the summer. Requirements: Cold temperatures Polar latitudes or high elevations Sufficient snow Flat area for snow to accumulate Permafrost is permanently frozen soil beneath a seasonal active layer that supports plant life Glaciers are made of compressed, recrystallized snow. Snow buildup in the zone of accumulation flows downhill into the zone of wastage. Glacier-Covered Areas Glacier Coverage (km2) No glaciers in Australia! 160,000 glaciers total 47 countries have glaciers 94% of Earth’s ice is in Greenland and Antarctica Mountain Glaciers are Retreating Worldwide The Antarctic Ice Sheet The Greenland Ice Sheet Glaciers flow downhill through ductile (plastic) deformation & by basal sliding. Brittle deformation near the surface makes cracks, or crevasses. Antarctic ice sheet: ductile flow extends into the ocean to form an ice shelf. Wilkins Ice shelf Breakup http://www.youtube.com/watch?v=XUltAHerfpk The Greenland Ice Sheet has fewer and smaller ice shelves. Erosional Features Unique erosional landforms remain after glaciers melt. -
Minimal Geological Methane Emissions During the Younger Dryas-Preboreal Abrupt Warming Event
UC San Diego UC San Diego Previously Published Works Title Minimal geological methane emissions during the Younger Dryas-Preboreal abrupt warming event. Permalink https://escholarship.org/uc/item/1j0249ms Journal Nature, 548(7668) ISSN 0028-0836 Authors Petrenko, Vasilii V Smith, Andrew M Schaefer, Hinrich et al. Publication Date 2017-08-01 DOI 10.1038/nature23316 Peer reviewed eScholarship.org Powered by the California Digital Library University of California LETTER doi:10.1038/nature23316 Minimal geological methane emissions during the Younger Dryas–Preboreal abrupt warming event Vasilii V. Petrenko1, Andrew M. Smith2, Hinrich Schaefer3, Katja Riedel3, Edward Brook4, Daniel Baggenstos5,6, Christina Harth5, Quan Hua2, Christo Buizert4, Adrian Schilt4, Xavier Fain7, Logan Mitchell4,8, Thomas Bauska4,9, Anais Orsi5,10, Ray F. Weiss5 & Jeffrey P. Severinghaus5 Methane (CH4) is a powerful greenhouse gas and plays a key part atmosphere can only produce combined estimates of natural geological in global atmospheric chemistry. Natural geological emissions and anthropogenic fossil CH4 emissions (refs 2, 12). (fossil methane vented naturally from marine and terrestrial Polar ice contains samples of the preindustrial atmosphere and seeps and mud volcanoes) are thought to contribute around offers the opportunity to quantify geological CH4 in the absence of 52 teragrams of methane per year to the global methane source, anthropogenic fossil CH4. A recent study used a combination of revised 13 13 about 10 per cent of the total, but both bottom-up methods source δ C isotopic signatures and published ice core δ CH4 data to 1 −1 2 (measuring emissions) and top-down approaches (measuring estimate natural geological CH4 at 51 ± 20 Tg CH4 yr (1σ range) , atmospheric mole fractions and isotopes)2 for constraining these in agreement with the bottom-up assessment of ref. -
Modelling the Transfer of Supraglacial Meltwater to the Bed of Leverett Glacier, Southwest Greenland
The Cryosphere, 9, 123–138, 2015 www.the-cryosphere.net/9/123/2015/ doi:10.5194/tc-9-123-2015 © Author(s) 2015. CC Attribution 3.0 License. Modelling the transfer of supraglacial meltwater to the bed of Leverett Glacier, Southwest Greenland C. C. Clason1, D. W. F. Mair2, P. W. Nienow3, I. D. Bartholomew3, A. Sole4, S. Palmer5, and W. Schwanghart6 1Department of Physical Geography and Quaternary Geology, Stockholm University, 106 91 Stockholm, Sweden 2Geography and Environment, University of Aberdeen, Aberdeen, AB24 3UF, UK 3School of Geosciences, University of Edinburgh, Edinburgh, EH8 9XP, UK 4Department of Geography, University of Sheffield, Sheffield, S10 2TN, UK 5Geography, College of Life and Environmental Sciences, University of Exeter, Exeter, EX4 4RJ, UK 6Institute of Earth and Environmental Science, University of Potsdam, 14476 Potsdam-Golm, Germany Correspondence to: C. C. Clason ([email protected]) Received: 23 June 2014 – Published in The Cryosphere Discuss.: 29 July 2014 Revised: 12 December 2014 – Accepted: 24 December 2014 – Published: 22 January 2015 Abstract. Meltwater delivered to the bed of the Greenland melt to the bed matches the observed delay between the peak Ice Sheet is a driver of variable ice-motion through changes air temperatures and subsequent velocity speed-ups, while in effective pressure and enhanced basal lubrication. Ice sur- the instantaneous transfer of melt to the bed in a control sim- face velocities have been shown to respond rapidly both ulation does not. Although both moulins and lake drainages to meltwater production at the surface and to drainage of are predicted to increase in number for future warmer climate supraglacial lakes, suggesting efficient transfer of meltwa- scenarios, the lake drainages play an increasingly important ter from the supraglacial to subglacial hydrological systems. -
Sea Level and Climate Introduction
Sea Level and Climate Introduction Global sea level and the Earth’s climate are closely linked. The Earth’s climate has warmed about 1°C (1.8°F) during the last 100 years. As the climate has warmed following the end of a recent cold period known as the “Little Ice Age” in the 19th century, sea level has been rising about 1 to 2 millimeters per year due to the reduction in volume of ice caps, ice fields, and mountain glaciers in addition to the thermal expansion of ocean water. If present trends continue, including an increase in global temperatures caused by increased greenhouse-gas emissions, many of the world’s mountain glaciers will disap- pear. For example, at the current rate of melting, most glaciers will be gone from Glacier National Park, Montana, by the middle of the next century (fig. 1). In Iceland, about 11 percent of the island is covered by glaciers (mostly ice caps). If warm- ing continues, Iceland’s glaciers will decrease by 40 percent by 2100 and virtually disappear by 2200. Most of the current global land ice mass is located in the Antarctic and Greenland ice sheets (table 1). Complete melt- ing of these ice sheets could lead to a sea-level rise of about 80 meters, whereas melting of all other glaciers could lead to a Figure 1. Grinnell Glacier in Glacier National Park, Montana; sea-level rise of only one-half meter. photograph by Carl H. Key, USGS, in 1981. The glacier has been retreating rapidly since the early 1900’s. -
Calving Processes and the Dynamics of Calving Glaciers ⁎ Douglas I
Earth-Science Reviews 82 (2007) 143–179 www.elsevier.com/locate/earscirev Calving processes and the dynamics of calving glaciers ⁎ Douglas I. Benn a,b, , Charles R. Warren a, Ruth H. Mottram a a School of Geography and Geosciences, University of St Andrews, KY16 9AL, UK b The University Centre in Svalbard, PO Box 156, N-9171 Longyearbyen, Norway Received 26 October 2006; accepted 13 February 2007 Available online 27 February 2007 Abstract Calving of icebergs is an important component of mass loss from the polar ice sheets and glaciers in many parts of the world. Calving rates can increase dramatically in response to increases in velocity and/or retreat of the glacier margin, with important implications for sea level change. Despite their importance, calving and related dynamic processes are poorly represented in the current generation of ice sheet models. This is largely because understanding the ‘calving problem’ involves several other long-standing problems in glaciology, combined with the difficulties and dangers of field data collection. In this paper, we systematically review different aspects of the calving problem, and outline a new framework for representing calving processes in ice sheet models. We define a hierarchy of calving processes, to distinguish those that exert a fundamental control on the position of the ice margin from more localised processes responsible for individual calving events. The first-order control on calving is the strain rate arising from spatial variations in velocity (particularly sliding speed), which determines the location and depth of surface crevasses. Superimposed on this first-order process are second-order processes that can further erode the ice margin. -
Ice Flow Impacts the Firn Structure of Greenland's Percolation Zone
University of Montana ScholarWorks at University of Montana Graduate Student Theses, Dissertations, & Professional Papers Graduate School 2019 Ice Flow Impacts the Firn Structure of Greenland's Percolation Zone Rosemary C. Leone University of Montana, Missoula Follow this and additional works at: https://scholarworks.umt.edu/etd Part of the Glaciology Commons Let us know how access to this document benefits ou.y Recommended Citation Leone, Rosemary C., "Ice Flow Impacts the Firn Structure of Greenland's Percolation Zone" (2019). Graduate Student Theses, Dissertations, & Professional Papers. 11474. https://scholarworks.umt.edu/etd/11474 This Thesis is brought to you for free and open access by the Graduate School at ScholarWorks at University of Montana. It has been accepted for inclusion in Graduate Student Theses, Dissertations, & Professional Papers by an authorized administrator of ScholarWorks at University of Montana. For more information, please contact [email protected]. ICE FLOW IMPACTS THE FIRN STRUCTURE OF GREENLAND’S PERCOLATION ZONE By ROSEMARY CLAIRE LEONE Bachelor of Science, Colorado School of Mines, Golden, CO, 2015 Thesis presented in partial fulfillMent of the requireMents for the degree of Master of Science in Geosciences The University of Montana Missoula, MT DeceMber 2019 Approved by: Scott Whittenburg, Dean of The Graduate School Graduate School Dr. Joel T. Harper, Chair DepartMent of Geosciences Dr. Toby W. Meierbachtol DepartMent of Geosciences Dr. Jesse V. Johnson DepartMent of Computer Science i Leone, RoseMary, M.S, Fall 2019 Geosciences Ice Flow Impacts the Firn Structure of Greenland’s Percolation Zone Chairperson: Dr. Joel T. Harper One diMensional siMulations of firn evolution neglect horizontal transport as the firn column Moves down slope during burial. -
N National Museum of Natural History June 2002 Number 10
ewsletterewsletter Smithsonian Institution NN National Museum of Natural History June 2002www.mnh.si.edu/arctic Number 10 NOTES FROM THE DIRECTOR for the University of Maryland. Irwin Shapiro, Director of By Bill Fitzhugh the Smithsonian Astrophysical Observatory, has been named Interim Under Secretary; and Douglas Erwin has been named In thirty two years at the Smithsonian, I have never Interim Director of NMNH while the search for a permanent experienced a year quite like the last one. In the past, the person for both positions continues. Yours Truly has become Smithsonian seemed immune from worldly upheavals, and Chair of Anthropology (a post I held from 1975-80). By this sailed steadily forward even in troubled times. During these time next year the Science Commission Report will have been years, the Institution changed physically and intellectually, on the table for six months, and I hope to report new directions increased the social and ethnic diversity of its staff and and improved prospects for Smithsonian science. programming, and began to diversify its funding stream; but the basic commitment to scholarship and research remained solid. *** Today, this foundation is being challenged as never before. The result has been an unusual year, to say the least. A Despite difficult times, the ASC has maintained its core stream of directors—seven or eight at last count—have left programs and has initiated new projects. At long last, Igor their posts; a special commission has investigated American Krupnik and I, with assistance from Elisabeth Ward, History’s exhibition program; a congressional science succeeded in realizing the dream of a dedicated ASC monograph commission is evaluating Smithsonian science; and two series. -
High Arctic Holocene Temperature Record from the Agassiz Ice Cap and Greenland Ice Sheet Evolution
High Arctic Holocene temperature record from the Agassiz ice cap and Greenland ice sheet evolution Benoit S. Lecavaliera,1, David A. Fisherb, Glenn A. Milneb, Bo M. Vintherc, Lev Tarasova, Philippe Huybrechtsd, Denis Lacellee, Brittany Maine, James Zhengf, Jocelyne Bourgeoisg, and Arthur S. Dykeh,i aDepartment of Physics and Physical Oceanography, Memorial University, St. John’s, Canada, A1B 3X7; bDepartment of Earth and Environmental Sciences, University of Ottawa, Ottawa, Canada, K1N 6N5; cCentre for Ice and Climate, Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark, 2100; dEarth System Science and Departement Geografie, Vrije Universiteit Brussel, Brussels, Belgium, 1050; eDepartment of Geography, University of Ottawa, Ottawa, Canada, K1N 6N5; fGeological Survey of Canada, Natural Resources Canada, Ottawa, Canada, K1A 0E8; gConsorminex Inc., Gatineau, Canada, J8R 3Y3; hDepartment of Earth Sciences, Dalhousie University, Halifax, Canada, B3H 4R2; and iDepartment of Anthropology, McGill University, Montreal, Canada, H3A 2T7 Edited by Jeffrey P. Severinghaus, Scripps Institution of Oceanography, La Jolla, CA, and approved April 18, 2017 (received for review October 2, 2016) We present a revised and extended high Arctic air temperature leading the authors to adopt a spatially homogeneous change in reconstruction from a single proxy that spans the past ∼12,000 y air temperature across the region spanned by these two ice caps. 18 (up to 2009 CE). Our reconstruction from the Agassiz ice cap (Elles- By removing the temperature signal from the δ O record of mere Island, Canada) indicates an earlier and warmer Holocene other Greenland ice cores (Fig. 1A), the residual was used to thermal maximum with early Holocene temperatures that are estimate altitude changes of the ice surface through time. -
Comparison of Remote Sensing Extraction Methods for Glacier Firn Line- Considering Urumqi Glacier No.1 As the Experimental Area
E3S Web of Conferences 218, 04024 (2020) https://doi.org/10.1051/e3sconf/202021804024 ISEESE 2020 Comparison of remote sensing extraction methods for glacier firn line- considering Urumqi Glacier No.1 as the experimental area YANJUN ZHAO1, JUN ZHAO1, XIAOYING YUE2and YANQIANG WANG1 1College of Geography and Environmental Science, Northwest Normal University, Lanzhou, China 2State Key Laboratory of Cryospheric Sciences, Northwest Institute of Eco-Environment and Resources/Tien Shan Glaciological Station, Chinese Academy of Sciences, Lanzhou, China Abstract. In mid-latitude glaciers, the altitude of the snowline at the end of the ablating season can be used to indicate the equilibrium line, which can be used as an approximation for it. In this paper, Urumqi Glacier No.1 was selected as the experimental area while Landsat TM/ETM+/OLI images were used to analyze and compare the accuracy as well as applicability of the visual interpretation, Normalized Difference Snow Index, single-band threshold and albedo remote sensing inversion methods for the extraction of the firn lines. The results show that the visual interpretation and the albedo remote sensing inversion methods have strong adaptability, alonger with the high accuracy of the extracted firn line while it is followed by the Normalized Difference Snow Index and the single-band threshold methods. In the year with extremely negative mass balance, the altitude deviation of the firn line extracted by different methods is increased. Except for the years with extremely negative mass balance, the altitude of the firn line at the end of the ablating season has a good indication for the altitude of the balance line. -
Glacier (And Ice Sheet) Mass Balance
Glacier (and ice sheet) Mass Balance The long-term average position of the highest (late summer) firn line ! is termed the Equilibrium Line Altitude (ELA) Firn is old snow How an ice sheet works (roughly): Accumulation zone ablation zone ice land ocean • Net accumulation creates surface slope Why is the NH insolation important for global ice• sheetSurface advance slope causes (Milankovitch ice to flow towards theory)? edges • Accumulation (and mass flow) is balanced by ablation and/or calving Why focus on summertime? Ice sheets are very sensitive to Normal summertime temperatures! • Ice sheet has parabolic shape. • line represents melt zone • small warming increases melt zone (horizontal area) a lot because of shape! Slightly warmer Influence of shape Warmer climate freezing line Normal freezing line ground Furthermore temperature has a powerful influence on melting rate Temperature and Ice Mass Balance Summer Temperature main factor determining ice growth e.g., a warming will Expand ablation area, lengthen melt season, increase the melt rate, and increase proportion of precip falling as rain It may also bring more precip to the region Since ablation rate increases rapidly with increasing temperature – Summer melting controls ice sheet fate* – Orbital timescales - Summer insolation must control ice sheet growth *Not true for Antarctica in near term though, where it ʼs too cold to melt much at surface Temperature and Ice Mass Balance Rule of thumb is that 1C warming causes an additional 1m of melt (see slope of ablation curve at right) -
Glacial Morphology of the Cary Age Deposits in a Portion of Central Iowa John David Foster Iowa State University
Iowa State University Capstones, Theses and Retrospective Theses and Dissertations Dissertations 1-1-1969 Glacial morphology of the Cary age deposits in a portion of central Iowa John David Foster Iowa State University Follow this and additional works at: https://lib.dr.iastate.edu/rtd Recommended Citation Foster, John David, "Glacial morphology of the Cary age deposits in a portion of central Iowa" (1969). Retrospective Theses and Dissertations. 17570. https://lib.dr.iastate.edu/rtd/17570 This Thesis is brought to you for free and open access by the Iowa State University Capstones, Theses and Dissertations at Iowa State University Digital Repository. It has been accepted for inclusion in Retrospective Theses and Dissertations by an authorized administrator of Iowa State University Digital Repository. For more information, please contact [email protected]. GLACIAL MORPHOLOGY OF THE CARY AGE DEPOSITS IN A PORTION OF CENTRAL IOWA by John David Foster A Thesis Submitted to the . • Graduate Faculty in Partial Fulfillment of The Requirements for the Degree of MASTER OF SCIENCE Major Subject: Geology Approved: Signatures have been redacted for privacy rs ity Ames, Iowa 1969 !/Y-J ii &EW TABLE OF CONTENTS Page ABSTRACT vii INTRODUCTION Location 2 Drainage 3 Geologic Description 3 Preglacial Topography 6 Pleistocene Stratigraphy 12 Acknowledgments . 16 GLACIAL GEOLOGY 18 General Description 18 Glacial Geology of the Study Area 18 Till Petrofabric Investigation 72 DISCUSSION 82 Introduction 82 Hypothetical Regime of the Cary Glacier 82 Review -
Greenland's Ice Cap Super Melting Is Currently Losing 200 Cubic Kilometres Our Swiss Army Kit for of Ice Each Year — and Accelerating
MORE GOOD STUFF Speeding up! ADSL DIY We show you how to make Turbocharge your Internet your PC run faster. without having to call in the geeks. Communities: Mon, 21 Aug 2006 You are in: Cooltech > Science & Nature BLOGS CLASSIFIEDS ENVIRONMENT CONVERTERS Greenland's ice cap super DOWNLOADS melting FEATURES Fri, 11 Aug 2006 GAMES MOBILE MAGIC The vast ice cap that covers most of NEW IDEAS Greenland is melting at a spectacular rate, and three times faster than five NEWSLETTER years ago, reports National Geographic SCIENCE & NATURE News. Swiss Army Kit SPACE SWISS ARMY KIT This is according to a new study, Frustrated published online by the journal Science, More Science & Nature TECH NEWS with your PC? which further indicates that Greenland Check out THE GADGET CORNER Greenland's ice cap super melting is currently losing 200 cubic kilometres our Swiss Army Kit for of ice each year — and accelerating. 'Warrior' gene 'linked' to Maori violence the answer! eMail the Ads by Goooooogle Where there's muck, there's Monet Cooltech Editor if you The study also finds that the melting Electric Snow Melt have a problem, and polar ice is raising sea levels around the Elephants show capacity for compassion we'll do our best to Cables globe. This could have a serious impact First koala born in Africa help! Waterproof Electric as global sea levels will rise by 6.5 Heating Cable Thick metres if all the ice on Greenland were China promises smog-free Olympics means durability.Since The Tech Set to melt, which could result in many Adventurer finishes 327km Thames swim 1930 islands being wiped out and even low- www.WarmYourFloor.com lying countries such as the Netherlands.