California's glaciers are retreating

Ice-free peaks of Sierra Nevada have never been seen by humans

- By Ian James

THE EAST LYELL glacier, shown in 2021, has lost an estimated 95% of its volume since the late 1800s.

Ian James Los Angeles Times

For as long as there have been people in what is now California, the granite peaks of the Sierra Nevada have held masses of ice, according to new research that shows the glaciers have probably existed since the last Ice Age more than 11,000 years ago.

The remnants of these glaciers, which have already shrunk dramatically since the late 1800s, are retreating year after year, and are projected to melt completely this century as global temperatures continue to rise.

In a study published last week, scientists examined the distant past of some of the largest glaciers in the Sierra Nevada by chipping away pieces of bedrock near the edges of the ice and analyzing the rocks.

They found that at two large glaciers, one in Yosemite National Park and another bordering the park, the rocks have continuously been covered, most likely by ice, since the end of the last Ice Age. They also found that another smaller glacier, which has mostly melted, has probably existed for at least 7,000 years, longer than previously known.

“It means that when these glaciers die off, we will be the first humans to see ice-free peaks in Yosemite,” said Andrew Jones, a researcher at the University of Wisconsin, Madison, who led the study.

The findings in the journal Science Advances indicate the Sierra's glaciers are older than suggested by previous research.