Various wild excitement about methane emissions from the Arctic shelf… Hot Topic, Inel and The Indescribably Overhyped, which latter reveals “exclusively” what Magnus translated several weeks ago.
Inel, very sensibly, asks for context: what are we to make of “millions of tons of a gas 20 times more damaging than carbon dioxide”? I think the best thing to look at would be the global methane concentration. If that isn’t going up strongly, then this isn’t a big thing at present. Whether or not its a sign for the future is another matter. Unfortunately I couldn’t find the current methane concs on the wub, so I thought I’d ask you lot.
[Update: pulled out from a comment by C (thanks):
“Atmospheric composition, radiative forcing, and climate change as a consequence of a massive methane release from gas hydrates” Shmidt/Shindell 2003.
From Table 2.1:
M ….. T
1 ….. 8.4
2.5 … 10.1
4 ….. 11.5
7 ….. 13.4
10 …. 16.7
40 …. 26.9
100 … 41.1
200 … 42.5
M = multiple of current concentration.
T = CH4 lifetime (years)
Shakhova states there’s 540 Gt total at least and 50 Gt of CH4 ready to go on the Siberian shelf (see Gareth above). So that could double residence time.]