Shallow fuels bring bad news

Geologists have discovered underwater deposits of hydrates — icy deposits of frozen methane gas — at far shallower depths under the ocean floor than expected. The finding suggests that, in a globally warmed world, the hydrates could melt suddenly and release their gas into the atmosphere, thus warming the planet even more.

Hydrates are cage-like structures in which molecules of water surround frozen molecules of gas. When dug up and brought to the surface, they release fizzy bubbles of methane into the atmosphere.

As a greenhouse gas, methane has 20 times the global warming potential of carbon dioxide. Large amounts of the world's carbon is locked up in methane hydrates, both in polar permafrost regions and buried in marine sediments worldwide. So scientists have long worried about a potentially catastrophic melting of these hydrates, triggered by an underwater landslide or warming of the ocean waters above them, that could send temperatures soaring.

from Nature