BOB HIRSHON (host):
Mysterious undersea craters explained. I’m Bob Hirshon and this is Science Update.
Enormous craters more than three football fields wide pock the floor of the Barents Sea near Norway. University of Norway geophysicist Karin Andreassen describes them in the journal Science.
KARIN ANDREASSEN (University of Norway, and CAGE Centre for Arctic Gas Hydrate, Environment and Climate):
They are actually carved into lithified hard bedrock.
Andreassen and her colleagues report that the craters formed from eruptions of natural gas. The glaciers of the last Ice Age acted as a lid on those gases, squeezing them into a solid form known as methyl hydrate.
And when the ice sheets retreated, the gas hydrates abruptly decomposed and formed these huge craters.
The scientists say retreating glaciers in Greenland and Antarctica might trigger similar eruptions of methane — a potent greenhouse gas that will add to yet more warming. I’m Bob Hirshon, for AAAS, the science society.
Story by Bob Hirshon