The mountain glaciers of Yosemite National Park are projected to melt away in 75 years or less. Now, new research finds that their loss will be the first time humans have ever seen the Sierra Nevada mountains without ice.
According to a new study, published Wednesday (Oct. 1) in the journal Science Advances, the Sierra Nevada's glaciers have not disappeared since the last ice age. Because they reached their maximum extent during the ice age about 30,000 years ago, and because humans aren't thought to have arrived in North America until after 30,000 years ago, that means people have never witnessed an ice-free Sierra Nevada, according to the study.
