Historic Photos Show Yosemite's Lyell Glacier as It Edges Towards Oblivion

The glaciers in California's Yosemite National Park could be lost in just 28 years. The glaciers' retreat can be seen in historic images, with images dating back almost 150 years showing the extent of how much has been lost.

Glaciers, which were first formed 10,000 years ago, were essential to the formation of Yosemite's landscape. Now only two glaciers remain in the park—the Lyell glacier and the Maclure glacier.

The Lyell Glacier, which lies on the slopes of Mount Lyrell, in the Sierra Nevada range of California, is the largest glacier in Yosemite National Park. It was discovered in 1871 by John Muir.

But it is rapidly disappearing and could be gone entirely by 2050, a new study by the United Nations Educational, Scientific and Cultural Organization (UNESCO) and the International Union for Conservation of Nature (IUCN) has found.

The study pointed to climate change as the reason for the shrinking glaciers. As carbon dioxide and other greenhouse gasses continue to pollute the world's atmosphere, the climate is getting warmer, melting the world's ice as a result.

The result can be seen in one image, taken of the Lyell glacier in 1883.

In the image, the glacier is nearly completely covered in snow, while by comparison, a picture taken in 2013 shows ice only covering its top portion.

When they are thick enough, glaciers move and flow under their own weight. A 2012 study found that the Maclure glacier was moving of one inch per day. However, the Lyell glacier no longer moves because the ice is too thin.

Yosemite's glaciers are not the only ones to face this threat.

The UNESCO study, published on November 3, found that the glaciers of the world are melting at a rapid rate. These include UNESCO World Heritage sites such as Mount Kilimanjaro, Yellowstone National Park and the Canadian Rocky Mountains. The study said it is necessary to limit gloabal warming to 1.5C (34.7F) to avoid any more glacier loss.

"Melting glaciers are the largest contributor to rising sea levels, and a poignant symbol of how human actions are transforming our environment," Climate scientist and presenter Ella Gilbert told Newsweek. "The [UNESCO] report shows that we have already pushed some glaciers too far, with the loss of iconic tropical glaciers like those on Kilimanjaro now inevitable. But two-thirds of the world's remaining glaciers can still be saved. This saddening report should serve as a stark reminder of the necessity to take action and keep warming to 1.5C."

Lyell glacier, in particular, is vital to local ecosystems as it provides a year-round supply of water to the Lyell Fork of the Tuolumne River. According to the National Park Service, from 1883 to 2017, the surface areas of both the Lyell Glacier and Maclure Glacier decreased by 67 to 78 percent.

But this is not the only reason melting glaciers are bad news.

Simon Cook, senior lecturer in environmental change at the University of Dundee told Newsweek that melting glaciers can make landscapes increasingly dangerous.

"Glaciers are shrinking in almost all parts of the world. And they appear to be shrinking very rapidly," Cook said. "There's a sense that as these glasses shrink, these landscapes are becoming more dangerous. So more of these ice avalanches and glacier collapses. There's also more potential for landslides and catastrophic floods, and so on."

"There are more widespread impacts as well, in some parts of the world glaciers are very important for water supply, and for driving hydropower, and for irrigation and as these glaciers become small, they can't continue to supply water at the same rate, and then that becomes a problem."

The major question is whether these vital glaciers can be saved.

"In this situation, with glaciers, there tends to be a lag time between any kind of climate influence and glaciers responding, so... we're kind of committed to a certain amount of glacier recession," Cook said. "Even if we're managed to keep global warming to within 1.5 degrees C of sort of pre-industrial temperature, we're going to lose some of these glaciers. But if we are able to limit global warming to that 1.5 C limit, then we might preserve many of these around the world and that is of significant importance because they are an incredibly important water supply."