John Metcalfe was CityLab’s Bay Area bureau chief, covering climate change and the science of cities.
Warm, dry weather could spell the doom of this Yosemite landmark.
How warm has California been lately? Well, look at the bottom image below and see if you can tell it was once a mighty glacier:
The top photo, taken in 1883 by Israel Russell of the U.S. Geological Survey, shows the expanse of California’s Lyell Glacier, the biggest in Yosemite National Park. In its golden years the frozen block was a true behemoth, but balmy weather has melted it down to a virtual ice cube, as shown in the 2015 photo by the National Park Service’s Keenan Takahashi.
As of this year, the landmark has lost about 80 percent of its 19th-century surface area of a half square-mile—and more than 10 percent of that loss happened in the past four years, according to NASA. Much of the blame can be ascribed to the hot, dry weather that’s been plaguing the West, and NASA isn’t shy about throwing in the double-C term. The space agency writes:
Yosemite National Park Glaciers are important indicators of climate change because they are sensitive to environmental conditions. The Lyell Glacier, larger of the two glaciers in Yosemite National Park and second largest in the Sierra Nevada mountains, has thinned noticeably even in just the last few years.
The pace of recent melting is evident in this comparison from the Septembers of 2009 and 2014:
“Newly exposed bedrock is visible on the east (left) side of the 2014 image,” says NASA. “The glacier is currently estimated to be 15 to 20 feet thick, losing about three feet of thickness each year. Slowly flowing glaciers are credited with sculpting much of Yosemite’s scenery.”
Here’s one more historical contrast from 1901 and 2011 posted by Yosemite park ranger Bob Roney:
In a poignant discussion of Lyell’s withering, Roney bemoans the likely fact that future generations won’t get to walk the glacier’s gelid barrens:
The ice continues to melt and by Yosemite National Park’s second centennial [in 2116] it may be completely gone. For hundreds of years, snow and ice melt from the foot of these two glaciers has fed the Tuolumne River and kept it flowing even in late summer and fall when other streams have dried.
Over the years I’ve made several attempts to climb Mount Lyell and its glacier but each time lightning storms in summer or avalanche danger in winter prevented me from completing the ascent. Although this may be disappointing to me, I am truly saddened by the fact that the last of our glaciers, these icy icons of wildness, may disappear within the lifetimes of my children and with them a source of late summer water for streamside life along the Tuolumne River.