Methane, a notorious greenhouse gas, is leaking from the permafrost under the Siberian seabed.

The apparent rapid decay of permafrost as a result of global warming.
The permafrost has small holes in it leading to the surface. Researchers found elevated levels of methane being emitted from the holes and even more in the water below the ground. The seabed is the source of the gas.
Methane is more than 20 times more efficient than carbon dioxide in trapping solar heat, so this is a huge problem. It is also emitted from many bogs and swamps across the world as organic matter decays and decomposes.
Scientists fear that global warming may cause Siberia’s permafrost to thaw and thereby release even more amounts of methane into the atmosphere. The effects of global warming are already readily apparent in the Arctic region from the melting of the polar ice caps etc.