This thread is too long to read in detail right now so I am sorry if this is repetitive.
Methane does not stink. It is totally odorless. That's why gas detectors are needed in coal mines. In earlier years canaries were taken into mines and when they died the miners got out quickly. What stinks is other gases sometimes found mixed in like hydrogen sulphide and sulpher dioxide. Methane constantly leaks from both land and seabed into the atmosphere, especially from coal deposits. It is said to be many times stronger as a greenhouse gas tha CO2.
In coal mining areas you can often watch bubbles rise in ponds and lakes, or if by the ocean, from docks on a calm day. When ponds freeze over in colder areas methane is sometimes trapped beneath the ice and sometimes by drilling a small hole a flare can be made by igniting the escaping gas. Scientists tell us that we can change global warming by reducing CO2 emissions. They offer no solution for natural methane emission which is far worse so I doubt that CO2 reduction by itself will do it!