Knock Knock. Who’s There? Not a Glacier, They’re Retreating

Paige Lary
May 30, 2017

This semester, many science students have been working on their end-of-the-year science projects, and my friend Kiley and I are no exception. For our project, Kiley and I decided to analyze photographs of local glaciers taken from the past and juxtapose them with recent photographs of the same glaciers to observe the effects of climate change.

While it is common to see environmentalists on TV or on the internet warning of glacial retreat due to climate change, it is easy to neglect the danger these big hunks of ancient ice face. After all, eastern California isn’t like Greenland, covered in enormous ice sheets. However, eastern California does possess Alpine glaciers (for example, the southernmost glacier in the continental US is the Palisade glacier near Big Pine) high in the mountains. Kiley and I chose to study glaciers in local areas, such as Yosemite National Park, and the results were shocking.

This image is a comparison of a photograph taken by G. K. Gilbert of Maclure Glacier in 1903 and Basagic’s photograph taken in 2004. Adapted from Hassan’s Sierra Nevada RePhoto digital photo album.

According to research conducted by Hassan Basagic, a scientist who is well-known for his glacier rephotographs, over the 101 years between 1903 and 2004, three important Yosemite glaciers have melted significantly. The surface area of Dana glacier decreased by 64% between 1903 and 2004, the surface area of Maclure glacier decreased by 47%, while the westernmost portion of Lyell glacier decreased by 40% and the eastern section of Lyell glacier decreased by 78%.

 This image shows West Lyell, and was taken in 1932 by Jeff Thomson during the Yosemite National Park glacier survey. Adapted from Report of Glacier Measurements, Mt. Lyell, Mt. Maclure, Mt. Dana, Mt. Conness, Mt. Koip, Mt. Kuna by C. A. Harwell, published in 1932. Courtesy of glaciers.us.
For comparison, this image, taken by Hassan Basagic, shows West Lyell from the same vantage point (the west moraine). Adapted from Basagic’s photograph collection High Sierra Glacier Change: A Collection of Repeat Photography 1883-2008.

These glaciers have great ecological value. Dana glacier’s summertime runoff contributes to the Lee Vining Creek, which feeds into Mono Lake. Mono Lake relies on inlets to maintain its delicate ecosystem, and without Dana glacier, Mono Lake would be losing a valuable hydrological input. Maclure and Lyell glaciers are also the headwaters of the Tuolumne River that flows throughout Yosemite National Park. The Tuolumne River is a significant water source for many local organisms, and if its glacial headwaters disappeared, the wildlife and vegetation in the national park would be put at risk. The Tuolumne River not only encourages tourists to visit Yosemite as well, but the river also provides water to the Hetch-Hetchy reservoir, the main water source of San Francisco and much of the Bay Area. Without these glaciers, there would be much environmental and economical damage to the Sierra Nevada. Wildlife and vegetation would be negatively affected, and without the beauty contributed to by the runoff of these glaciers, tourism would certainly decrease.

Glaciers serve as an exemplary indicator concerning climate change, and, as is observed in the comparison of historical and modern day glaciers, climate change is in effect in the Sierra Nevada.

The top image of Lyell Glacier was taken by D. H. Hubbard in 1954. The rephoto was taken by Hassan Basagic in 2004. Adapted from Basagic’s photograph collection High Sierra Glacier Change: A Collection of Repeat Photography 1883-2008.
This graph, courtesy of Greg Stock, is a visual representation of the surface area change of the Maclure and Lyell Glaciers from 1883-2014, with data obtained from Basagic and Fountain’s Quantifying 20th Century Glacier Change in the Sierra Nevada, California (2011). According to Stock’s article Vanishing Ice, Vanishing History, the surface area of the Maclure and Lyell Glaciers has decreased by 80%, with 10% of that decrease occurring within the last four years (as of 2015).

 

 

 

This image was taken during the 1969 Yosemite National Park glacier survey by either Edwin Rockwell or Norman Messinger. Adapted from Report of Glacier Studies in Yosemite National Park 1969 by assistant park naturalist of Yosemite National Park William R. Jones, published in 1969. Courtesy of glaciers.us.
This image was taken by Jeff Thomson during Yosemite National Park’s glacier survey in 1932. Adapted from Report of Glacier Measurements, Mt. Lyell, Mt. Maclure, Mt. Dana, Mt. Conness, Mt. Koip, Mt. Kuna by C. A. Harwell, published in 1932. Courtesy of glaciers.us.