Coal Mining and Methane
The big push on the climate change fight has been the shutting down of coal fired power plants. However, this is only part of the problem with coal.
A significant amount of coal mined (rouhly half) is used in the “coking” process in the making of iron. Coal mining releases methane, CH4, a really bad green house gas that is many more times more potent than CO2. Some studies are indicating that methane may have caused up to a third of the global warming over the last one hundred years.
Here is a good article that describes the release of methane from coal mines.