For generations, Samuel Mendoza’s family operated the lift of the world’s highest ski resort on Mount Chacaltaya in the Bolivian Andes, elevation 17,785 feet. Samuel continues this tradition with quiet stoicism. From just outside La Paz, tourists come to this precarious, breathtaking destination to walk out in the clouds, onto a summit higher than the base camp of Mount Everest. Samuel treats them to tea and sympathy even as some succumb to altitude sickness. A few hundred feet below, at the Chacaltaya GAW Station, scientists monitor symptoms of climate change from the highest atmospheric observatory on earth. The mountain’s 18,000-year-old glacier has melted, and Samuel’s way of life is dissolving along with it.  DP