DOCSLIB.ORG

This Thesis Has Been Submitted in Fulfilment of the Requirements for a Postgraduate Degree (E.G

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
This Thesis Has Been Submitted in Fulfilment of the Requirements for a Postgraduate Degree (E.G This thesis has been submitted in fulfilment of the requirements for a postgraduate degree (e.g. PhD, MPhil, DClinPsychol) at the University of Edinburgh. Please note the following terms and conditions of use: • This work is protected by copyright and other intellectual property rights, which are retained by the thesis author, unless otherwise stated. • A copy can be downloaded for personal non-commercial research or study, without prior permission or charge. • This thesis cannot be reproduced or quoted extensively from without first obtaining permission in writing from the author. • The content must not be changed in any way or sold commercially in any format or medium without the formal permission of the author. • When referring to this work, full bibliographic details including the author, title, awarding institution and date of the thesis must be given. Satellite investigations of ice dynamics and supraglacial lake development in Greenland Kate H. Briggs PhD University of Edinburgh School of Geosciences College of Science and Engineering 2011 Declaration This thesis embodies 4.5 years of my life. It was composed by myself and the work contained herein is my own, and where chapters have been prepared for submission to journals the authorship and contributions are noted appropriately. This thesis has not been submitted for any other degree or professional qualification. Kate H. Briggs Acknowledgements I have rather a lot of people to thank for the guidance, support and kindness they have shown me throughout the past four (and the rest) years of my PhD. First of all, I am thankful to my supervisors, Andy Shepherd and Pete Nienow, for both their academic guidance and for giving me patience and understanding when I really needed it. Beyond the guidance of my supervisors I have had many useful discussions with, and advice from, the members of the glaciology group in Edinburgh (and now Leeds) past and present - Malcolm McMillan, Steve Palmer, Eero Rinne, Aud Sundal, Ian Bartholomew, Tom Cowton, Stew Jamieson, Vicki Parry, Andy Hein, Mehmet Karatay, Andy Sole, Andy Wright, Neil Ross, Santiago de la Pena and Noel Gourmelen. I want to extend special thanks to Steve Palmer, Eero Rinne and Malcolm McMillan for all the help they have given me. I am grateful to IT help at Edinburgh, in particular Chris Place and Steve Dowers, for resolving my computing woes. As important as the academic support received during my PhD has been the support provided by friends and family. To my office mates Lynsey Callaghan, Michaela Newton, Ian Bartholomew, Matthew Brolly, Martin Hurst, Steve Palmer, Richard Streeter, Eero Rinne, Tom Cowton, Ed Mitchard, Mal McMillan and Katharine Fitzpatrick, who I shared the PhD experience with, for general advice, the occasional rant and a lot of the all important banter- thank you! Thanks to my good friends, Katharine Fitzpatrick, Elizabeth Richardson, Carolyn Anderson, Anna Jagan, Mal McMillan, Rik Higham, Eero Rinne, Tom Russon, Steve Palmer, Innes Keighren, Richard Phillips, Steve Binnie, Addy Pope, Raph Bleakley, Mehmet Karatay, Hannah Mathers and Jennifer Wyllie with whom I have shared many good chats, tasty meals, ESSENTIAL tea and cake breaks, cinema trips, great runs, climbs and walks, and lovely holidays throughout my PhD, all of which have kept me smiling! Thanks to my family; Mum, Adam, Lynda, Pam, Vicky, Daisy, Grandma and Aunty Joan, for being generally wonderful and making me feel so secure. And last, but not least, to my Dad, who in my opinion IS the best Dad in the world – your love and support made this possible for me- thank you! Contents Contents Contents ………………………………………………………………………... i List of figures …………………………………………………………………... iii List of tables ……………………………………………………………………. iv Abstract …………………………………………………………….................... 1 Chapter 1 Introduction …………………………………………………. 3 1.1 Aim ……………………………………………….……….......... 3 1.2 Motivation ……………………………………………………… 3 1.2 Thesis structure…………………………………………………. 8 Chapter 2 Greenland Ice Sheet flow dynamics ………………………… 9 2.1 Introduction …………………………………………………….. 9 2.2 Dynamic changes at marine margins due to ice-ocean interactions ……………………………………………………... 10 2.2.1 Ocean induced acceleration of marine-terminating glaciers ... 11 2.2.2 Atmosphere induced acceleration of marine-terminating glaciers ……………………………………………………… 15 2.2.3 Deceleration and stabilisation of marine-terminating glaciers 16 2.3 Surface meltwater forcing of inland and land-terminating ice dynamic changes………………………………………………... 17 2.3.1 Daily to seasonal velocity variations of inland and land- terminating ice ………………………………………………. 18 2.3.2 Interannual velocity variations of inland and land- terminating ice ………………………………………………. 22 2.4 Summary ……………………………………………………….. 24 2.5 Thesis objectives ……………………………………………….. 26 Chapter 3 Review of methods ………………………………………….. 28 3.1 Ice velocity retrieval methods ………………………………….. 28 3.1.1 Interferometric SAR (InSAR) ………………………………. 29 3.1.2 Feature tracking with optical images ……………………….. 33 3.1.3 Offset tracking with SAR images …………………………… 35 3.2 Digital elevation models ………………………………………... 37 3.2.1 Ground based DEM acquisition …………………………….. 37 3.2.2 Airborne DEM acquisition ………………………………….. 38 3.2.3 Spaceborne DEM acquisition ……………………………….. 41 3.3 Supraglacial lake analysis ……………………………………… 50 3.3.1 Data …………………………………………………………. 51 3.3.2 Classification of lake areas ………………………………….. 53 3.4 Summary ……………………………………………………….. 57 Chapter 4 Seasonal flow variability of outlet glaciers in Northeast Greenland …………………………………………………… 59 4.1 Abstract ………………………………………………………… 60 4.2 Introduction …………………………………………………….. 60 4.3 Data and methods ………………………………………………. 64 4.4 Results …………………………………………………………. 66 4.4.1 Along glacier velocity profiles ……………………………… 66 i Contents 4.4.2 Time series observations ……………………………………. 68 4.5 Discussion ……………………………………………………… 73 4.5.1 Spatial flow patterns ………………………………………… 73 4.5.2 Seasonal flow patterns ………………………………………. 75 4.6 Conclusions …………………………………………………….. 78 4.7 Limitations ……………………………………………………... 79 4.8 Appendix ……………………………………………………...... 82 Chapter 5 Coincidence of supraglacial lakes and topographic depressions in Northeast Greenland ………………………… 84 5.1 Abstract ………………………………………………………… 85 5.2 Introduction …………………………………………………….. 86 5.3 Methods ………………………………………………………... 88 5.3.1 InSAR DEM ………………………………………………… 88 5.3.2 Sinks in the InSAR DEM …………………………………… 92 5.3.3 Supraglacial lakes in optical imagery ……………………….. 92 5.3.4 Sink and lake area comparisons …………………………….. 93 5.4 Results ………………………………………………………….. 94 5.5 Discussion ……………………………………………………… 98 5.6 Conclusions …………………………………………………….. 100 5.7 Limitations ……………………………………………………... 101 5.8 Appendix ……………………………………………………...... 102 Chapter 6 Investigating and predicting supraglacial lake drainage on the Greenland Ice Sheet ……………………………………... 103 6.1 Abstract ………………………………………………………… 105 6.2 Introduction …………………………………………………….. 106 6.3 Methods ………………………………………………………... 108 6.3.1 MODIS image processing …………………………………... 109 6.3.2 DEM generation …………………………………………….. 110 6.3.3 Temperature data ……………………………………………. 110 6.3.4 Slope profiles ………………………………………………... 111 6.4 Results ………………………………………………………….. 111 6.5 Discussion …………………………………………………….... 120 6.5.1 Distribution of lakes ………………………………………… 120 6.5.2 Lake drainage ……………………………………………….. 121 6.5.3 Timing of lake drainage events relative to PDD temperatures 122 6.5.4 Projecting lake formation and drainage to higher elevations .. 123 6.6 Conclusions …………………………………………………….. 124 6.7 Limitations ……………………………………………………... 125 Chapter 7 Synthesis and conclusions …………………………………... 127 7.1 Introduction …………………………………………………….. 127 7.2 Summary of the principal conclusions …………………………. 128 7.2.1 Seasonal velocity variability in the northeast of Greenland … 128 7.2.2 Comparison of sink and lake locations in the northeast of Greenland …………………………………………………… 129 7.2.3 Spatial and temporal trends in lake formation and drainage in the west of Greenland ……………………………………….. 131 7.2.4 Synthesis …………………………………………………….. 133 7.3 Wider implications ……………………………………………... 134 ii Contents 7.3.1 Seasonal velocity variability ………………………………... 134 7.3.2 Complex tidewater glacier behaviour ………………………. 138 7.3.3 Predicting the future formation and drainage of lakes ……… 139 7.4 Further work …………………………………………………… 141 7.4.1 Future work on velocity variability at the northeast margin of the GrIS ……………………………………………………... 141 7.4.2 Future work on the use of DEMs to map and predict supraglacial lake coverage ………………………………….. 143 7.4.3 Future work on understanding and predicting supraglacial lake drainage events ………………………………………… 144 7.6 Concluding remarks ……………………………………………. 145 References ……………………………………………………………………… 146 List of figures Figure 1.1: Past and future global mean sea level ……………………………… 4 Figure 1.2: The extent of the GrIS today and during the last interglacial ……… 5 Figure 1.3: Modelled future evolution of the GrIS …………………………….. 6 Figure 1.4: Remote sensing estimates of GrIS mass balance ………………….. 7 Figure 2.1: West Greenland ocean temperatures 1991-2006 …………………... 13 Figure 2.2: Circulation in a West Greenland fjord ……………………………... 14 Figure 2.3: Supraglacial lakes …………………………………………………. 22 Figure 3.1: SAR phase shift ……………………………………………………. 30 Figure 3.2: Differential interferometry ………………………………………… 32 Figure 3.3: Ice surface feature displacement …………………………………… 34 Figure 3.4: Coherence tracking image …………………………………………. 36 Figure 3.5: Terrestrial photogrammetry DEM …………………………………. 38 Figure 3.6: NASA ATM flightlines in Greenland
Load more

Recommended publications
  • 2007 – 2008 – Roger Moe, Former Democratic Letter from Will Steger
    ANNUAL REPORT 2007–2008 INSPIRE EMPOWER EDUCATE SOLAR WIND TABLE OF CONTENTS 1 The Will Steger Foundation (WSF) is dedicated to creating programs that foster international “ [Will Steger and the leadership and cooperation through environmental education and policy. WSF] were the ones that brought the left and the WSF seeks to inspire, educate and empower the world to understand the threat of and solutions right into the center on to global warming. this issue [global warm- CHANGE ACTION ing].” ANNUAL REPORT 2007 – 2008 – Roger Moe, former Democratic Letter from Will Steger...................................................................................................... 2 Congressman Letter from the Executive Director ................................................................................... 4 Fostering Leadership and International Cooperation ...................................................... 6 Inspiring Others through the Eyewitness Account .......................................................... 8 Empowering Others through Education ........................................................................ 10 Global Warming 101 initiative ....................................................................................... 18 Media Outreach .............................................................................................................. 24 Supporters ....................................................................................................................... 26 2801 21st Avenue South, Suite
    [Show full text]
  • Rapid Loss of the Ayles Ice Shelf, Ellesmere Island, Canada Luke Copland,1 Derek R
    GEOPHYSICAL RESEARCH LETTERS, VOL. 34, L21501, doi:10.1029/2007GL031809, 2007 Click Here for Full Article Rapid loss of the Ayles Ice Shelf, Ellesmere Island, Canada Luke Copland,1 Derek R. Mueller,2 and Laurie Weir3 Received 24 August 2007; accepted 5 October 2007; published 3 November 2007. [1] On August 13, 2005, almost the entire Ayles Ice Shelf permanent, as there is little to no evidence of recent ice (87.1 km2) calved off within an hour and created a new shelf regrowth after calving. 2 66.4 km ice island in the Arctic Ocean. This loss of one of [4] This paper focuses on the rapid loss of almost all of the six remaining Ellesmere Island ice shelves reduced their the Ayles Ice Shelf on August 13, 2005, and associated overall area by 7.5%. The ice shelf was likely weakened events involving the calving of the Petersen Ice Shelf and prior to calving by a long-term negative mass balance loss of semi-permanent MLSI along N. Ellesmere Island. related to an increase in mean annual temperatures over the We document and explain these phenomena using a series past 50+ years. The weakened ice shelf then calved during of satellite images, seismic records, buoy drift tracks, the warmest summer on record in a period of high winds, weather records, climate reanalysis and tide models. All record low sea ice conditions and the loss of a semi- times quoted here have been standardized to Coordinated permanent landfast sea ice fringe. Climate reanalysis Universal Time (UTC). suggests that a threshold of >200 positive degree days À1 year is important in determining when ice shelf calving 2.
    [Show full text]
  • Iceberg Calving Dynamics of Jakobshavn Isbrę, Greenland
    ICEBERG CALVING DYNAMICS OF JAKOBSHAVN ISBRÆ, GREENLAND By Jason Michael Amundson RECOMMENDED: Advisory Committee Chair Chair, Department of Geology and Geophysics APPROVED: Dean, College of Natural Science and Mathematics Dean of the Graduate School Date ICEBERG CALVING DYNAMICS OF JAKOBSHAVN ISBRÆ, GREENLAND A THESIS Presented to the Faculty of the University of Alaska Fairbanks in Partial Fulfillment of the Requirements for the Degree of DOCTOR OF PHILOSOPHY By Jason Michael Amundson, B.S., M.S. Fairbanks, Alaska May 2010 iii Abstract Jakobshavn Isbræ, a fast-flowing outlet glacier in West Greenland, began a rapid retreat in the late 1990’s. The glacier has since retreated over 15 km, thinned by tens of meters, and doubled its discharge into the ocean. The glacier’s retreat and associated dynamic adjustment are driven by poorly-understood processes occurring at the glacier-ocean in- terface. These processes were investigated by synthesizing a suite of field data collected in 2007–2008, including timelapse imagery, seismic and audio recordings, iceberg and glacier motion surveys, and ocean wave measurements, with simple theoretical considerations. Observations indicate that the glacier’s mass loss from calving occurs primarily in sum- mer and is dominated by the semi-weekly calving of full-glacier-thickness icebergs, which can only occur when the terminus is at or near flotation. The calving icebergs produce long-lasting and far-reaching ocean waves and seismic signals, including “glacial earth- quakes”. Due to changes in the glacier stress field associated with calving, the lower glacier instantaneously accelerates by ∼3% but does not episodically slip, thus contradicting the originally proposed glacial earthquake mechanism.
    [Show full text]
  • Holocene Dynamics of the Arcticts Largest Ice Shelf
    Holocene dynamics of the Arctic’s largest ice shelf SEE COMMENTARY Dermot Antoniadesa,1,2, Pierre Francusa,b,c, Reinhard Pienitza, Guillaume St-Ongec,d, and Warwick F. Vincenta aCentre d’études nordiques, Université Laval, Québec, QC, Canada G1V 0A6; bInstitut National de la Recherche Scientifique: Eau, Terre et Environnement, Québec, QC, Canada G1K 9A9; cGEOTOP Research Center, Montréal, QC, Canada H3C 3P8; and dInstitut des sciences de la mer de Rimouski, Rimouski, QC, Canada G5L 3A1 Edited by Eugene Domack, Hamilton College, Clinton, NY, and accepted by the Editorial Board September 21, 2011 (received for review April 20, 2011) Ice shelves in the Arctic lost more than 90% of their total surface deposition (17, 18); driftwood-based dates are consequently rec- area during the 20th century and are continuing to disintegrate ognized as providing only upper limits to ice-shelf ages (12, 18, rapidly. The significance of these changes, however, is obscured 19). The history of the ice shelves of northern Ellesmere Island by the poorly constrained ontogeny of Arctic ice shelves. Here we and the significance of their recent decline therefore remains use the sedimentary record behind the largest remaining ice shelf unclear. Here we present a continuous paleoenvironmental re- in the Arctic, the Ward Hunt Ice Shelf (Ellesmere Island, Canada), to construction of conditions within the water column of Disraeli establish a long-term context in which to evaluate recent ice-shelf Fiord, where changes directly caused by the WHIS were recorded deterioration. Multiproxy analysis of sediment cores revealed pro- by a series of biological and geochemical proxy indicators.
    [Show full text]
  • Routine Monitoring of Ice Islands
    Ice Analyst Workshop Case Study Routine Monitoring Of Ice Islands WMO IAW-2 Tromso Norway Laurie Weir CIS Vladimir Bessonov AARI June 15-19 2009 Outline • Ice Shelves to Ice Islands • Resources & tools for analysis • Partnerships in tracking • Imagery Review Ice Shelf Genesis • Ice shelves found in the Canadian High arctic are created by very different processes than their Antarctic counterparts. • The Canadian ice shelves are Ward Hunt Ice Shelf created by accumulations of snow and basal accretion on multiyear Ayles Ice Shelf land-fast ice occurring over a long period of time, while the Antarctic Milne Ice Shelf and southern Greenlandic is shelves are created by glacial Petersen Ice systems located on land Shelf extending over the ocean. Serson Ice • This has sometimes led to the Shelf former being termed “ice shelves” and the latter being termed “glacial ice tongues”. (Dowdeswell et al 1994, Jeffries 1987) Wesley Van Wychen CIS CO-OP 2007 Whats going on? • Ice Shelves are Calving as a result of a combination of: – Long-term temperature increases leads to – Long-term reduction in ice shelf thickness; – Dramatic reductions in arctic sea ice leads to more ▪ Open water at the shelf face for extended periods in summer – 2005 & 2008 saw record warm temperatures – High winds (Dr Luke Copland University of Ottawa) Ice Island Calving Mechanisms • With warmer temperatures weakening the ice structure here are some scenarios: • Scenario 1: Persistent winds, tidal action and pressure from the surrounding ice pack may cause cracks to develop within ice shelf: thus producing and ice island. (Holdsworth 1971, Jeffries 1985) Winds Tidal Action Ice Pack Pressure Wesley Van Wychen CIS CO-OP 2007 Ice Island Calving Mechanisms • Scenario 2: Vibrations due to wave action cause a resonance that causes stresses in the ice shelf to the point where a fracture can occur.
    [Show full text]
  • Factors Contributing to Recent Arctic Ice Shelf Losses
    Chapter 10 Factors Contributing to Recent Arctic Ice Shelf Losses Luke Copland, Colleen Mortimer, Adrienne White, Miriam Richer McCallum, and Derek Mueller Abstract A review of historical literature and remote sensing imagery indicates that the ice shelves of northern Ellesmere Island have undergone losses during the 1930s/1940s to 1960s, and particularly since the start of the twenty-first century. These losses have occurred due to a variety of different mechanisms, some of which have resulted in long-term reductions in ice shelf thickness and stability (e.g., warm- ing air temperatures, warming ocean temperatures, negative surface and basal mass balance, reductions in glacier inputs), while others have been more important in defining the exact time at which a pre-weakened ice shelf has undergone calving (e.g., presence of open water at ice shelf terminus, loss of adjacent multiyear land- fast sea ice, reductions in nearby epishelf lake and fiord ice cover). While no single mechanism can be isolated, it is clear that they have all contributed to the marked recent losses of Arctic ice shelves, and that the outlook for the future survival of these features is poor. Keywords Ice shelf • Calving • Multiyear landfast sea ice • Mass balance • Climate warming • Glaciers L. Copland (*) • A. White Department of Geography, Environment and Geomatics, University of Ottawa, Ottawa, ON, Canada e-mail: [email protected]; [email protected] C. Mortimer Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, AB, Canada e-mail: [email protected] M. Richer McCallum • D. Mueller Department of Geography and Environmental Studies, Carleton University, Ottawa, ON, Canada e-mail: [email protected]; [email protected] © Springer Science+Business Media B.V.
    [Show full text]
  • Ebook Download Arctic Ice Shelves and Ice Islands 1St Edition Kindle
    ARCTIC ICE SHELVES AND ICE ISLANDS 1ST EDITION PDF, EPUB, EBOOK Luke Copland | 9789402410990 | | | | | Arctic Ice Shelves and Ice Islands 1st edition PDF Book Point 7 deserves a bit of elaboration. Invertebrate Zoology, 11 1 , 1—2. Derek Mueller. Kahl, J. Afanasyev, I. Army Corps of Engineers. Given the rate of climate change across the Arctic, this book is an extremely timely contribution and will interest a range of individuals. The buttressing shelves accumulate cracks on their surfaces as glaciers push against them from behind, and cracks also appear as the shelf pushes against the curvature of the shoreline. Displacement, it stays the same. Global Change Biology, 17 2 , — Scientists theorize that this is what happened to an ice shelf known as Larsen B, which lost 1, square miles 3, square kilometers of ice over the course of a few weeks in , according to The National Snow and Ice Data Center. Mueller and his collaborators at the University of British Columbia and University of California, Davis were studying the flow of water through this channel. Radionov Eds. Time is of the essence. Polychaeta of the Arctic Ocean p. Zasko, D. A tale of two basins: An integrated physical and biological perspective of the deep Arctic Ocean. Life on an ice island [Pod Nogami Ostrov Ledyanoi] 2nd ed. Recent fracturing and breakup events of ice shelves in the Canadian High Arctic have attracted significant scientific and public attention, and produced large ice islands which may pose a risk to Arctic shipping and offshore infrastructure. The Canadian Ice Service will monitor the remaining ice shelves and track these islands, especially if they drift further south where they can pose a hazard to oil rigs and ships.
    [Show full text]
  • Dynamic Response of an Arctic Epishelf Lake to Seasonal and Long-Term Forcing: Implications for Ice Shelf Thickness Andrew K
    The Cryosphere Discuss., doi:10.5194/tc-2017-19, 2017 Manuscript under review for journal The Cryosphere Discussion started: 16 March 2017 c Author(s) 2017. CC-BY 3.0 License. Dynamic response of an Arctic epishelf lake to seasonal and long-term forcing: implications for ice shelf thickness Andrew K. Hamilton1,2, Bernard E. Laval1, Derek R. Mueller2, Warwick F. Vincent3, and Luke Copland4 1Department of Civil Engineering, University of British Columbia, Vancouver, British Columbia, Canada 2Geography and Environmental Studies, Carleton University, Ottawa, Ontario, Canada 3Department of Biology and Centre for Northern Studies (CEN), Université Laval, Quebec City, Quebec, Canada 4Department of Geography, Environment, and Geomatics, University of Ottawa, Ottawa, Ontario, Canada Correspondence to: A. K. Hamilton ([email protected]) Abstract. Changes in the depth of the freshwater-seawater interface in epishelf lakes have been used to infer long-term changes in the thickness of ice shelves, however, little is known about the dynamics of epishelf lakes and what other factors may influence their depth. Continuous observations collected between 2011 and 2014 in the Milne Fiord epishelf lake, in the Canadian Arctic, 5 showed that the depth of the halocline varied seasonally by up to 3.3 m, which was comparable to interannual variability. The seasonal depth variation was controlled by the magnitude of surface meltwater inflow and the hydraulics of the inferred outflow pathway, a narrow basal channel in the Milne Ice Shelf. When seasonal variation and an episodic mixing of the halocline were accounted for, long-term records of depth indicated there was no significant change in thickness of ice along the basal channel 1 from 1983 to 2004, followed by a period of steady thinning at 0.50 m a− between 2004 and 2011.
    [Show full text]
  • Ice Island Calvings and Ice Shelf Changes, Milne Ice Shelf and Ayles Ice Shelf, Ellesmere Island, N.W.T
    ARCTIC VOL. 39, NO. 1 (MARCH 1986) P. 15-19 Ice Island Calvings and Ice Shelf Changes, Milne Ice Shelf and Ayles Ice Shelf, Ellesmere Island, N.W.T. MARTIN 0.JEFFRIES’ (Received 14 November 1984; accepted in revised form 1 I April 1985) ABSTRACT. Analysisof vertical air photographs taken 1959 in and 1974 reveals that a total of 48 km’, involving 3.3 km3, ofice calved from Milne and Ayles ice shelves between July 1959 and July 1974. In addition, Ayles Ice Shelf moved about 5 km out of Ayles Fiord. It still occupied this exposed position in July1984. The ice losses and movements have allowed the growth of thickice that sea has developed an undulating topographysimilar to but smaller scale than that of theice shelves. It is suggested that regular monitoring ofcoastal the ice of northernEllesmere Island wouldenable such changes to be registered and assessed, as they could be of concern to offshoreoperations in the Beaufort Sea. Key words: air photographs, Milne Ice Shelf, Ayles Ice Shelf, ice island calvings, thick sea ice growth R6SUME. Une analysede photographies driennes verticales prises en1959 et 1974 rdvdla qu’un totalde 48 km2, comprenant 3.3 km3, de dktachades plateaux de glace Milne et Ayles entre juillet 1959 et juillet 1974. De plus, le plateau de glace Ayles seddplaCa de quelque 5 km a l’extdrieur du fjord Ayles. Le plateau occupait toujourscette position enjuillet 1984. Le vtlage et les ddplacements de la glace ont peds la formation d’une dpaisse glace marine qui a ddvelopp6 une topographie vallonnde semblable h celle des plateaux de glace, mais une plus petite dchelle.
    [Show full text]
  • Ice-Shelf Collapse, Climate Change, and Habitat Loss in the Canadian High Arctic W
    Polar Record 37 (201): 133-142 (2001). Printed in the United Kingdom. 133 Ice-shelf collapse, climate change, and habitat loss in the Canadian high Arctic W. F. Vincent De'partement de Biologie and Centre d'Etudes Nordiques, University Laval, Sainte-Foy, Quebec G1K 7P4, Canada J.A.E. Gibson CSIRO Marine Research, GPO Box 1538, Hobart, Tasmania 7001, Australia M.O. Jeffries Geophysical Institute, University of Alaska, PO Box 757320 Fairbanks, AK 99775-7320, USA Received July 2000 ABSTRACT. Early explorers in the Canadian high Arctic described a fringe of thick, landfast ice along the 500-km northern coast of Ellesmere Island. This article shows from analyses of historical records, aerial photographs, and satellite imagery (ERS-1, SPOT, RADARSAT-1) that this ancient ice feature ('Ellesmere Ice Shelf) underwent a 90% reduction in area during the course of the twentieth century. In addition, hydrographic profiles in Disraeli Fiord (83°N, 74° W) suggest that the ice-shelf remnant that presently dams the fiord (Ward Hunt Ice Shelf) decreased in thickness by 13 m (27%) from 1967 to 1999. Mean annual air temperatures at nearby Alert station showed a significant warming trend during the last two decades of this period, and a significant decline in the number of freezing degree days per annum. The ice-dammed fiord provides a stratified physical and biological environment (epishelf lake) of a type that is otherwise restricted to Antarctica. Extensive meltwater lakes occur on the surface of the ice shelf and support a unique microbial food web. The major contraction of these ice-water habitats foreshadows a much broader loss of marine cryo-ecosystems that will accompany future wanning in the high Arctic.
    [Show full text]
  • The Way of the Reindeerp. 12–13
    Arctic Bulletin No 1.07 • PUBLISHED BY THE WWF I nte R N Ati O N A L AR C T I C P RO G RA MME The way of the reindeer p. 12–13 Arctic view on latest global climate report p. 4–5, p. 16–17 Summer sea ice gone by 2040? p. 6 Pressure on Greenland’s narwhals p. 8 Canadian tar sands and the Arctic p. 21–22 2 WWF ARCTIC BULLETIN • No. 1.07 Contents l Bush lifts drilling ban in Alaska’s Bristol Bay p. 11 l Rapid climate change and the sea ice ecosystem p. 14–16 Sustainable livelihoods in Kamchatka p. 12–13 l l Hunting of Chukotka’s polar bears? p. 9 l Pipeline assessment must include how gas will be used p. 10 l What in tar nation? p. 21–22 l IPCC and the Arctic p. 4–5 l Intense period of polar research p. 8 Ice-free arctic summers by 2040? p. 6–7 l l Populations of polar bear in decline p. 9 Winter sea ice close to record low p. 6 l l Interview: Arctic view on global climate report p. 16–17 l Time for action p. 20–21 Massive ice sheet breaks away p. 7 l l WWF and Canon join forces on Polar Bear Tracker p. 23 l Greenland’s narwhals still in trouble p. 8 l Whaling undermines whale watching in Iceland p. 18–19 l WWF assists with Norwegian oil spill p. 10 l New director for the WWF International Arctic Programme p.
    [Show full text]
  • Tanker Attack Probe On
    DAILY COLLECTION OF MARITIME PRESS CLIPPINGS 2010 – 222 Number 222 *** COLLECTION OF MARITIME PRESS CLIPPINGS *** Tuesday 10-08-2010 News reports received from readers and Internet News articles copied from various news sites. SVITZER OCEAN TOWAGE Jupiterstraat 33 Telephone : + 31 2555 627 11 2132 HC Hoofddorp Telefax : + 31 2355 718 96 The Netherlands E-mail: [email protected] www : www.svitzer-coess.com The 95 ton bollard pull tug SMIT PANTHER seen moored in the Scheurhaven Rotterdam - Europoort Photo : Piet Sinke (c) Distribution : daily 13400+ copies worldwide 10-08-2010 Page 1 DAILY COLLECTION OF MARITIME PRESS CLIPPINGS 2010 – 222 Your feedback is important to me so please drop me an email if you have any photos or articles that may be of interest to the maritime interested people at sea and ashore PLEASE SEND ALL PHOTOS / ARTICLES TO : [email protected] If you don't like to receive this bulletin anymore : To unsubscribe click here (English version) or visit the subscription page on our website. http://www.maasmondmaritime.com/uitschrijven.aspx?lan=en-US EVENTS, INCIDENTS & OPERATIONS COLLISION OFF MUMBAI The Indian Coast Guard (ICG) has sounded an alert over the oil spill off the Mumbai coast, as the slick covered a large area, up to five nautical miles, from the spot where two ships collided on Saturday morning. The spill from MSC Chitra, after it collided with mv Khalijia-III, is estimated to be three to four tonnes an hour. Aggravating the situation is the continual falling of containers from the cargo of MSC Chitra, which is sinking, as the vessel tilted precariously “The oil has spread up to Uran, Mandwa, Elephanta Island and Butcher Island.
    [Show full text]