[aerohead]

Originally Posted by litesong

Hundreds of years ago, methane was 0.7ppm. As perma-frost thaws from AGW, theory considered that methane would be produced from the bio-mass. Ten(?) years ago, spot regions of Arctic perma-frost regions were reported over 2ppm methane & later 3ppm. Most recent evidence show spot readings of methane as high as 16ppm over waters on Siberian continental shelves. As methane bubbles toward the surface, much(most?) methane is absorbed in the waters, before reaching the sea & ocean surfaces. Of course, perma-frost thaws on land do not have absorptive ocean waters.
Yeah, we're below 2ppm methane.......... but not for long. Of course, there is way over the amount of perma-frost bio-mass, if heated, to produce many multiples of 2ppm atmospheric methane.

Also, small recent studies of third place GHG nitrous oxide emissions, long considered to be of negligible concern, show twelve times greater perma-frost thawing release than previously thought.

How 'bout this tidbit:
https://www.theguardian.com/environm...climate-crisis

Just wanted to share that,all the quanta I've seen for atmospheric Methane has been reported in parts-per-billion-by volume (ppbv)