High in California’s Sierra Nevada, a group of hikers gathers around an old photo of a glacier. They hold it up, compare it to the bare rock in front of them, and then scramble across a gurgling stream. On the other side, they start taking photos.

Byers: “Some places you look out across a landscape where there used to be a huge glacier, covered with snow and ice, and now you just see a rock cliff or a pile of boulders. And to see that change is really astounding.”

That’s Jonathan Byers, Director of the Alpine of the Americas Project. His group asks people who backpack, hike, or climb to collect data about how climate change is affecting mountain areas. Volunteers choose a historic photo of the American west, hike to the same place the previous photographer stood, and record the scene as it looks today.

Byers: “By going to those exact same places where they took those pictures, and repeating them, we can see the changes that have happened over the past 150 years.”

The photos provide valuable data for climate scientists. They’re also powerful visual proof of the growing impacts of global warming on the American landscape.

Reporting credit: ChavoBart Digital Media.

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Alpine of the Americas Project