How does the Greenhouse mechanism work
 

"Rodney Blackall" wrote
But we must not forget that every little rise in temperature melts a
little
bit of permafrost releasing methane. CH4 may be shorter lived in the
atmosphere but it has a much greater "greenhouse power" than CO2.

Methane levels are being monitored and are in decline for the moment -
probably a result of the tightening of industrial methane releases.

Nevertheless they are going down.

That may change as the tundra melts and rots.