Repeat Photography Project
Glaciers re-photographed by USGS since 1997
|Click on map for larger version. The red dots on this map represent selected repeat photographs of glaciers taken throughout Glacier National Park, Montana.|
Climate change research in Glacier National Park, Montana entails many methods of documenting the landscape change, including the decline of the parks namesake glaciers. While less quantitative than other high-tech methods of recording glacial mass, depth, and rate of retreat, repeat photography has become a valuable tool for communicating effects of global warming. With evidence of worldwide glacial recession and modeled predictions that all of the parks glaciers will melt by the year 2030, USGS scientists have begun the task of documenting glacial decline through photography. The striking images created by pairing historic images with contemporary photos has given global warming a face and made climate change a relevant issue to viewers. The images are an effective visual means to help viewers understand that climate change contributes to the dynamic landscape changes so evident in Glacier National Park.
The Repeat Photography Project began in 1997 with a systematic search of the archives at Glacier National Park. We began searching for historic photographs of glaciers in the vast collection that spans over a century. Many high quality photographs exist from the parks early photographers such as Morton Elrod, T.J. Hileman, Ted Marble, F.E. Matthes, and others who scoured the park to publicize its beauty and earn their livings. Copies of the historic photos were taken in the field to help determine the exact location of the original photograph. Photographing the glaciers cannot occur until the previous winters snow has melted on the glacial ice and when air quality conditions are considered at least good. This creates a narrow window in the northern clime of Glacier National Park where smoke from forest fires prevented photography on many occasions in the past few years. Since 1997 over sixty photographs have been repeated of seventeen different glaciers. Thirteen of those glaciers have shown marked recession and some of the more intensely studied glaciers have proved to be just 1/3 of their estimated maximum size that occurred at the end of the Little Ice Age (circa 1850). In fact, only 26 named glaciers presently exist of the 150 glaciers present in 1850 and those that do are mere remnants of their previous size. Other glaciers, such as Piegan Glacier, have remained visibly unchanged as a result of their north- northeast aspect and tendency to accumulate wind deposited snow along the Continental Divide. The photos of Piegan Glacier though, record dramatic change in foreground vegetation in response to climate change factors such as change in wildfire frequency and infestation of white pine blister rust. Close inspection of the photo pairs in this collection reveal many changes on a more subtle level than the obvious size reduction in glacial ice see what changes you can detect.