Arctic Sinkholes Preview
Preview: Season 49 Episode 1 | 30s | Video has closed captioning.
Colossal explosions shake a remote corner of the Siberian tundra, leaving behind massive craters. In Alaska, a huge lake erupts with bubbles of inflammable gas. Scientists are discovering that these mystifying phenomena add up to a ticking time bomb, as long-frozen permafrost melts and releases vast amounts of methane, a potent greenhouse gas.
Problems Playing Video? | Closed Captioning