The Shamrock Glacier in Lake Clark National Park and Preserve, Alaska, USA, has receded about 2 miles from its 1928 position near its terminal moraine. Some newly exposed morainal surfaces are now vegetated. 1928 photograph by Stephen R. Capps. 2004 repeat photography by M. Torre Jorgenson.


The Southwest Alaska Inventory & Monitoring Network (SWAN) is an office of the National Park Service dedicated to providing the scientific foundation for effective, long-term protection and management of natural resources in five units of the national park system. Collectively these units comprise approximately 9.4 million acres, 11.6 percent of the land managed by the National Park Service, or 2 percent of the Alaska landmass, and include a diversity of geologic features, ecosystems, fish, wildlife, and climatic conditions that are equaled few places in North America.
A multi-year project was initiated to assess landscape changes in the SWAN parks through the use of repeat photography. A total of 1,076 historical photographs dating as far back as 1895 have been acquired for these parks. A digital archive structure and ThumbsPlus-Access database have been developed to compile information about the photographs and prioritize them for repeat photography. The photographs are stored as high-resolution images for archiving and research, and low-resolution images for rapid review and broader distribution. The database allows the user to easily sort and view photographs by the desired data fields. A total of 214 photographs were recently repeated in three SWAN units: 59 in Lake Clark National Park and Preserve; 136 in Katmai National Park and Preserve, and 19 in Aniakchak National Monument and Preserve.
In comparing the old and recent photographs, it is evident that a variety of changes associated with vegetation succession and geomorphic processes have occurred within the parks. Volcanism in Katmai and Aniakchak has created extensive barren landscapes that for the most part have been slowly colonized except in favorable microsites. Most glaciers have shown dramatic retreat since the early 1900s, with newly exposed surfaces becoming rapidly vegetated by tall shrubs and trees at low elevations but remaining sparsely vegetated at higher elevations. Expansion of trees and shrubs was observed in western Katmai, and altitudinal increase in treeline was observed at many locations in Lake Clark and Katmai.
View the photo pairs.