GLACIERS OF NORTH AMERICA-GLACIERS OF ALASKA.
In the Preface, this book is referred to as a 'chapter'; it is the eighth released by the USGS as part of Professional Paper 1386: Satellite Image Atlas of Glaciers of the World, a series of 11 chapters. Remotely sensed images, principally from Landsat 1, 2, and 3, are employed in a study of the glacierized regions of the world produced under the series editorship of Richard S. Williams Jr. and Jane G. Ferrigno.
The Landsat images were acquired primarily during the mid to late 1970s and were used by an international team of glaciologists to study the various glacierized regions of the world and to discuss glaciological topics. Thus the present publication is one part of an immense project. Chapter 1386-K includes sections entitled "Columbia and Hubbard Tidewater Glaciers," by Robert M. Krimmel; "The 1986 and 2002 Temporary Closures of Russell Fiord by the Hubbard Glacier," by Bruce F. Molnia, Dennis C. Trabant, Rod S. March, and Robert M. Krimmel; and "Geospatial Inventory and Analysis of Glaciers: A Case Study for the Eastern Alaska Range," by William F. Manley.
In addition to the large number of satellite images, reproduced in both various forms of colour and monochrome, and the excellent maps derived from them, there are hundreds of oblique photographs taken from low-flying aircraft and from the ground. There are also historical photographs, many of them replicated during recent field visits. Together, this superb coverage provides the ultimate representation of Alaska's glaciers and, for most of them, illustrates their progressive thinning and retreat from the mid-19th century to the 21st century.
The wide range of reproductive techniques employed includes false-colour infrared image mosaics, digital enlargements, annotated Landsat 7 ETM+, and standard colour and black-and-white photography. The great majority of the images are nothing short of spectacular, providing not only a vital glaciological tool, but also a collection of great aesthetic beauty. Furthermore, the figures are supported by lengthy captions that contain a wealth of factual and interpretive detail.
In his introductory passages, author Molnia points out that Alaska has an area of 1 530693 [km.sup.2] of which 5% (about 75 000 [km.sup.2]) is presently covered by glacier ice. While there is no absolute count, the number of Alaska's glaciers exceeds 100000, even though a number have melted away completely in recent decades.
Part 1 of the book includes a section on 18th and 19th century glacier observations listed under well-known explorers, such as Vitus Bering, James Cook, Alexandra Malaspina, and George Vancouver. As coverage approaches the end of the 19th century, the available detail increases markedly. The Alaska-Canada Boundary Surveys between 1893 and 1920 produced an invaluable source of glacier photographs, as did the National Geographic Society Expeditions that began in the 1880s. This section continues through the work of William O. Field, Bradford Washburn, Austin Post, up to the present period, exemplified by Robert M. Krimmel.
Part 2 provides a series of individual essays on tidewater glaciers, surge-type glaciers, jokulhlaups (glacier outburst floods), and debris-covered glaciers. Each essay is illustrated by photographic examples.
Part 3, the main part of the book (pages 84 to 467), provides detailed descriptions of Alaska's 14 glacierized regions. It is followed by an exhaustive list of references cited (pages 487 to 504) and four useful appendices. Appendix A is an index of the 1:250 000-scale USGS topographical quadrangle maps of Alaska that show glaciers. Appendix B lists the l:63 360-scale USGS topographical quadrangle maps cited in the text. Appendix C, an index of all Alaskan glaciers that have been given official names by the United States Board on Geographic Names, also includes each glacier's latitude and longitude and the map sheet name (1:250 000) on which it appears. Finally, Appendix D provides a chronological list of pre-20th century Alaskan explorers, cartographers, historians, naturalists, and expeditions.
The USGS has embarked on an ambitious project; the item under review is only one part of it, yet a massive part. When complete, the entire exercise will have resulted in the most comprehensive world inventory and analysis of glaciers ever contemplated. Not only is this work invaluable for the advance of the discipline of glaciology, but it will also become the standard baseline upon which to assess the impacts of climate warming. While it is widely understood that glacier mass balance is controlled by several factors in addition to temperature, the current warming trend is of critical importance. Twenty years ago, the claims that climate warming was occurring initially met with widespread scepticism. As the field evidence from surveys of glaciers or the mapping of sea ice in high latitudes has multiplied, together with other evidence, so the news media and many of the original sceptics have changed their stand. This trend has continued to the point that today the public at large is regaled almost daily with catastrophe stories, which often are grossly exaggerated. In itself, this is a challenge to those who are committed to encouraging appropriate political response. To have at hand such an excellent factual baseline and analytical discussion of its implications represents a critical step forward. The fact that the satellite images date from more than 30 years ago encourages an immediate response for replication and determination of the extent of glacier change.
Jack D. Ives
Professor Emeritus, University of California
Honorary Research Professor,
Carleton University, Ottawa
412 Thessaly Circle, Ottawa, Ontario K1H 5W5, Canada
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|Author:||Ives, Jack D.|
|Article Type:||Book review|
|Date:||Dec 1, 2009|
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