DYNAMICS OF THE WEST ANTARCTIC ICE SHEET

Transcription

1 DYNAMICS OF THE WEST ANTARCTIC ICE SHEET

2 GLACIOLOGY AND QUATERNARY GEOLOGY A Series of Books

3 DYNAMICS OF THE WEST ANTARCTIC ICE SHEET Proceedings of a Workshop held in Utrecht, May 6-8, 1985 Edited by C. J. VAN DER VEEN and J. OERLEMANS Institute of Meteorology and Oceanography, State University of Utrecht, The Netherlands D. REIDEL PUBLISHING COMPANY A MEMBER OF THE KLUWER ACADEMIC PUBLISHERS GROUP DORDRECHT/BOSTON/LANCASTER/TOKYO

4 Library of Congress Cataloging in Publication Data Dynamics of the West Antarctic ice sheet. (g (Glaciology and Quaternary geology) Includes indexes. 1. Ice sheets~antarctic regions~congresses. 2. Oceanography~ Antarctic regions~congresses. l. Veen, C. J. van der (Cornelis J.), II. Oerlemans, J. (Johannes), III. Series. GB2598.W47D '12' ISBN -13: e-isbn -13: I DOl: / Published by D. Reidel Publishing Company, P.O. Box 17, 3300 AA Dordrecht, Holland. Sold and distributed in the U.S.A. and Canada by Kluwer Academic Publishers, 101 Philip Drive, Assinippi Park, Norwell, MA 02061, U.S.A. In all other countries, sold and distributed by Kluwer Academic Publishers Group, P.O. Box 322,3300 AH Dordrecht, Holland. All Rights Reserved 1987 by D. Reidel Publishing Company, Dordrecht, Holland Softcover reprint of the hardcover 1st edition 1987 No part of the material protected by this copyright notice may be reproduced or utilized in any form or by any means, electronic or mechanical including photocopying, recording or by any information storage and retrieval system, without written permission from the copyright owner

5 TABLE OF CONTENTS Preface List of participants vii ix The West Antarctic Ice Sheet C J VAN DER VEEN the need to understand its dynamics 1 Force budget of ice sheets I M WHILLANS 17 On the oceanic circulation near a shelf-ice edge G J F VAN HEIJST 37 Quantitative estimates of the mass flux and ice movement along the ice edges 1n the eastern and southern Weddell Sea M A LANGE 57 Some aspects of the flow of the Ronne Ice Shelf C S M DOAKE 75 Unconfined ice-shelf flow L W MORLAND 99 Plane and radial ice-shelf flow with prescribed temperature profile L W MORLAND and R ZAINUDDIN 117 Ice-shelf backpressure : form drag versus dynamic drag D R MACAYEAL 141 Ice stream-ice shelf interaction in West Antarctica R A BINDSCHADLER, D R MACAYEAL and S N STEPHENSON 161 A few preliminary results from the glaciogeophysical survey of the interior Ross Embayment (GSlRE) C R BENTLEY, S SHABTAIE, D D BLANKENSHIP, R B ALLEY and S T ROONEY 181 On the flow within the transition zone between ice sheet and ice shelf K HERTERICH 185

6 vi TABLE OF CONTENTS The finite-element method applied to a time-dependent flowband model J L FASTOOK 203 Longitudinal stresses and basal sliding C J VAN DER VEEN a comparative study 223 A subglacial aquifer bed model and water pressure dependent basal sliding relationship for a West Antarctic ice stream C S LINGLE and T J BROWN 249 The heat budget of the Ross drainage basin J OERLEMANS 287 Numerical modelling of the large-scale basal water flux under the West Antarctic Ice Sheet W F BUDD and D JENSSEN 293 Modelling the response of the West Antarctic Ice Sheet to a climatic warming W F BUDD, B J MCINNES, D JENSSEN and I N SMITH 321 Subject index 359 Geographic index 367

7 PREFACE Few scientists doubt the prediction that the antropogenic release of carbon dioxide in the atmosphere will lead to some warming of the earth's climate. So there is good reason to investigate the possible effects of such a warming, in dependence of geographical and socialeconomic setting. Many bodies, governmental or not, have organized meetings and issued reports in which the carbon dioxide problem is defined, reviewed, and possible threats assessed. The rate at which such reports are produced still increases. However, while more and more people are getting involved in the 'carbon dioxide business', the number of investigators working on the basic problems grows, in our view, too slowly. Many fundamental questions are still not answered in a satisfactory way, and the carbon dioxide building rests on a few thin pillars. One such fundamental question concerns the change in sea level associated with a climatic warming of a few degrees. A number of processes can be listed that could all lead to changes of the order of tens of centimeters (e.g. thermal expansion, change in mass balance of glaciers and ice sheets). But the picture of the carbon dioxide problem has frequently be made more dramatic by suggesting that the West Antarctic Ice Sheet is unstable, implying a certain probability of a 5 m higher sea-level stand within a few centuries. The massive amount of paper used to describe the possible consequences of such an event is in large contrast with the few scientific publications in which this potential instability of the West Antarctic Ice Sheet is discussed. In view of this situation, we were very pleased that we could find sponsors for a workshop on the dynamics of the West Antarctic Ice Sheet. The Ministry of Education and Science, the Royal Netherlands Meteorological Institute, and the Ministry of Housing, Development and Physical Planning all gave financial support, enabling us to invite a number of leading experts. The meeting was held in May 1985, at the Institute of Meteorology and Oceanography (University of Utrecht, The Netheriands). This book forms the proceedings, and consists of papers that were all written after the workshop, and certainly benefitted from the many discussions we had. We thank the reviewers for their work and cooperation, and we hope that the material in this volume will prove to be a valuable contribution to our understanding of the dynamics of the West Antarctic Ice Sheet. Utrecht, August 1986 C J van der Veen J Oerlemans vii

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9 LIST OF PARTICIPANTS C R BENTLEY Department of Geology and Geophysics / Geophysical and Polar Research Center, University of Wisconsin-Madison 1215 W Dayton Street, Madison, Wisconsin 53706, USA R A BINDSCHADLER NASA / Goddard Space Flight Center Code 671 Greenbelt, Maryland 20771, USA W F BUDD Meteorology Department, University of Melbourne Parkville, Victoria 3052, Australia H DECLEIR Geografisch Instituut, Vrije Universiteit Brussel Pleinlaan 2, B-1050 Brussel, Belgium C S M DOAKE British Antarctic Survey Madingley Road, Cambridge CB3 OET, England J L FASTOOK Institute for Quaternary Studies, University of Maine at Orono Boardman Hall, Orono, Maine 04469, USA T FICHEFET Institut d'astronomie et de geophysique, Universite Catholique de Louvain Chemin du Cyclotron 2, B-1348 Louvain-la-Neuve, Belgium W GREUELL Instituut voor Meteorologie en Oceanografie, Rijksuniversiteit Utrecht Princetonplein 5, 3584 CC Utrecht, The Netherlands K HERTERICH Max-Planck-Institut fur Meteorologie Bundesstrasse 55, 2000 Hamburg, West Germany G J F VAN HEIJST Instituut voor Meteorologie en Oceanografie, Rijksuniversiteit Utrecht Princetonplein 5, 3584 CC Utrecht, The Netherlands

10 x LIST OF PARTICIPANTS A KATTENBERG Royal Netherlands Meteorological Institute Postbus 201, 3730 AE De Bi1t, The Netherlands M A LANGE A1fred-Wegener-Institut fur Po1ar- und Meeresforschung Postfach , Columbusstrasse, D-2850 Bremerhaven, West Germany C S LINGLE CIRES / NOAA, University of Colorado Campus Box 449, Boulder, Colorado 80309, USA Now at Division of Polar Programs, National Science Foundation Washington,DC 20550, USA D R MACAYEAL Department of Geophysical Sciences, University of Chicago 5734 S Ellis Avenue, Chicago, Illinois 60637, USA L W MORLAND School of Mathematics and Physics, University of East Anglia Norwich NR4 7TJ, England J OERLEMANS Instituut voor Meteoro1ogie en Oceanografie, Rijksuniversiteit Utrecht Princetonplein 5, CC Utrecht, The Netherlands N REEH Section for Glaciology, Geological Survey of Greenland ~ster Voldgade 10., DK-1350 Copenhagen N, Denmark CRITZ Laboratoire de Glaciologie et Geophysique de l'environmehc B.P. 96, Saint Martin d'heres, France C J VAN DER VEEN Instituut voor Meteoro1ogie en Oceanografie, Rijksuniversiteit Utrecht Princetonplein 5, 3584 CC Utrecht, The Netherlands S VAN DER VEEN Instituut voor Meteoro1ogie en Oceanografie, Rijksuniversiteit Utrecht Princetonplein 5, 3584 CC Utrecht, The Netherlands I M WHILLANS Institute of Polar Studies and Department of Geology, Ohio State University 103 Mendenhall, 125 So.uth Oval Mall, Columbus, Ohio 43210, USA