The northern hemisphere obviously is more of a problem than the southern, except for an Argentinian hot spot.
It would seem that aggressive oil and gas development with losses in drilling, fracking, casing, and even flaring could be contributing factors that reportedly are grotesquely underestimated by the latest testing.
Permafrost melt due to global warming, and metling of ice sheets in Siberia, have also been put forth as contributing to “global warming” these daze.
Warming methane cathrates releases methane from the hydrate, raising concerns about deep sea deposits.