Some Arctic lakes are starting to look like witches’ cauldrons. In the Arctic, a frozen layer of soil – permafrost – trapped dead plants and animals for thousands of years. As the climate warms, that soil is beginning to thaw, releasing carbon dioxide and methane.

The above video shows an increasingly common site in northern latitudes. As global warming heats these areas up, the frozen ground is melting. And when permafrost turns from solid ground to looser mud, it releases gases that have been trapped inside.