As permafrost laced with buried ice thaws, the ground collapses, forming craters or lakes. This story appears in the September 2019 issue of National Geographic magazine. Sergey Zimov, right ...

After ten years, the mine had reached its present depth of 116 meters, and Yakutsk became known as the cradle of permafrost science. Permanently frozen ground, or permafrost, is a relic of the last ...