Skip to main content

Up Next

Arctic Sinkholes

Arctic Sinkholes

Season 49 Episode 1
53:30
What Are UFOs?

What Are UFOs?

Season 52 Episode 1
53:43
Extreme Airport Engineering

Extreme Airport Engineering

Season 52 Episode 2
53:40
Dino Birds

Dino Birds

Season 52 Episode 3
53:35
Egypt's Tombs of Amun

Egypt's Tombs of Amun

Season 52 Episode 4
53:40
Pompeii's Secret Underworld

Pompeii's Secret Underworld

Season 52 Episode 5
53:40
Baltimore Bridge Collapse

Baltimore Bridge Collapse

Season 52 Episode 6
53:32
Revolutionary War Weapons

Revolutionary War Weapons

Season 52 Episode 7
53:39
Secrets of the Forest

Secrets of the Forest

Season 52 Episode 8
53:41
Ultimate Crash Test: Countdown

Ultimate Crash Test: Countdown

Season 52 Episode 10
53:29
NOVA Season 52

Ultimate Crash Test: Impact

Season 52 Episode 11
53:27
Back to Show
NOVA

Arctic Sinkholes Preview

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.