A Yosemite glacier is dead, what that means for the planet's future

Mt Lyell, viewed from the John Muir Trail / Pacific Crest Trail on the shoulder North of Donahue Pass. Ansel Adams Wilderness, Sierra Nevada mountains, California. Credit: Wikimedia.org

John Muir, who’s known as the father of National Parks, was a key player in the efforts to preserve what is now Yosemite. He first gained fame for proving that massive glaciers carved the park’s iconic valley and the area around it. Muir did that by finding and documenting those glaciers in the late 1800s; since then, those glaciers have taught us a lot about the Earth. But now, one of those glaciers is dead.