Below the highest peaks in Yosemite National Park sit the park’s last two remaining glaciers, Lyell and Maclure. Yosemite Glaciers are slowly yet undeniably making a hasty retreat up the steep slopes they have been a part of for hundreds of years. Why should we care? These glaciers are responsible for replenishing the Tuolumne River, a key water source for northern California and powerful evidence of the ill effects of climate change.

Glaciers and Climate Change:

By definition, glacier ice has been around for a long time – hundreds to several hundred thousand years – making them a valuable tool for climate research. By drilling into the glacier an ice core can be extracted, providing pertinent clues about climate conditions over time, including global warming. A glacier’s inherent sensitivity to temperature fluctuations is a big help. Since the early days of data collection, Yosemite’s glaciers have been in steady retreat. Scientists point to the industrial revolution as the smoking gun, so to speak, firing up global warming.

“The reason glaciers are good indicators of climate change is because they are simple. Snowfall and temperature are the only two things that control a glacier’s health. So if you have less snow or warmer temperatures, the glaciers are going to retreat.” Greg Stock, a Yosemite National Park glaciologist.

Brief Backstory:

Yosemite’s glacier’s have been explored and studied, in earnest, since John Muir begain in 1872. Muir charted and mapped the glaciers as they changed over time. His passion caught the attention of President Theodore Roosevelt in 1903 and shortly thereafter the first American national park was born: Yosemite National Park. Today’s resident geologist, Gregg Stock, continues to track the glaciers and their dwindling appearance, hoping he will not be the last.