Scientists estimate that Alaska contains more than 100,000 glaciersincluding about 60 active and former tidewater glacierswhich cover approximately 75,000 km2, or about 5 percent of the State.
According to a new book published by the U.S. Geological Survey (USGS), most glaciers in every mountain range and island group in Alaska are undergoing significant retreat, thinning, or stagnation, especially glaciers at lower elevations. In places, these changes began as early as the middle of the 18th century.
Although a handful of Alaska's large glaciers are, surprisingly, advancing, more than 99 percent of them are retreating. In the past decade, Alaska's coastal glaciers have added as much (or more) meltwater to the global ocean as the ice sheets of Greenland or Antarctica, making these glaciers a significant factor in global sea-level rise.
Glaciers of Alaska, authored by USGS research geologist Bruce Molnia, presents a comprehensive overview of the state of Alaskan glaciers at the end of the 20th century and beginning of the 21st century. Richard Williams, Jr., an emeritus senior research glaciologist with the USGS, said the 550-page volume will serve as a major reference work for glaciologists studying glaciers in Alaska for decades to come.
The report uses a combination of satellite images, vertical aerial photographs (black-and-white and color-infrared photos taken from airplanes, looking straight down), oblique aerial photographs (color photos taken from the air at an angle, such as most regular photos), and maps, supported by the scientific literature, to document the distribution and behavior of glaciers throughout Alaska.
The author concludes that, because of the vast areas encompassed by the glaciated regions of Alaska, satellite remote sensing provides the only feasible means of monitoring changes in glacier area and in position of terminithe ends of glaciersin response to short- and long-term changes in the marine and continental climates of Alaska.
Alaskan glaciers occur in 11 mountain ranges, one large island, one island chain, and one archipelago. Details about the recent behavior of many of Alaska's glaciers are contained in this richly illustrated book, with multiple photographs and satellite images, as well as hundreds of aerial photographs taken by Molnia during his more than 4 decades of fieldwork in Alaska.
Three other USGS glaciologists authored two sidebar sections of the book: "Columbia and Hubbard Tidewater Glaciers," by Robert M. Krimmel; and "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. A third section, "Geospatial Inventory and Analysis of Glaciers: A Case Study for the Eastern Alaska Range," was authored by William F. Manley, Institute of Arctic and Alpine Research (INSTAAR), University of Colorado.
This book (USGS Professional Paper 1386-K), which is available in print and online at URL http://pubs.usgs.gov/pp/p1386k/, is the eighth chapter to be published in the Satellite Image Atlas of Glaciers of the World series. More than 100 glaciologists from the United States and other nations have collaborated with the USGS to produce this series, which will eventually contain 11 chapters. (See USGS Fact Sheet 2005-3056.)
in this issue:
Alaskan Glaciers Retreating