Arctic seafloor a big source of methane

Sediments had been thought to be capped by subsea permafrost

Prodigious plumes of planet-warming methane are bubbling from sediments across a broad region of Arctic seafloor previously thought to be sealed by permafrost, new analyses indicate. The resulting increase of methane gas in the atmosphere may accelerate climate warming, scientists say.

WARMING SIGNS With a boot for scale, this photo shows methane-rich bubbles accumulating beneath the sea ice of the East Siberian Arctic Shelf — a shallow, Greenland-sized swath of the Arctic Ocean that scientists recently discovered is leaking large amounts of planet-warming methane.