'Free Solo' climber Alex Honnold.National Geographic/Taylor Shaffer'Free Solo' climber Alex Honnold witnessed the effects of climate change throughout his career.He's seen glaciers and ice features melt away in Patagonia and Alaska.It inspired him to start the Honnold Foundation, investing in community-based solar energy projects.In 2023, world-famous climbers Alex Honnold (of "Free Solo" fame) and Tommy Caldwell tackled the Devils Thumb, a hazardous mountain in southeastern Alaska.Before their ascent, Honnold and Caldwell hiked to the mountain's base, tripping over piles of boulders.