More science on H2S and methane releases in relation to ozone collapse and corresponding catastrophic UV levels (PDF):

[link to acd.ucar.edu]

I'll quote a little:

"However, we also find that large quantities of
hydrogen sulfide create a significant decrease in tropospheric hydroxyl radical, leading to a commensurate increase in atmospheric methane. Therefore a large methane flux (possibly from methane clathrate destabilization, Siberian traps or hydrothermal vent complexes) combined with a large hydrogen sulfide oceanic flux is much more likely to lead to an ozone collapse than methane or hydrogen sulfide alone with implications to the Permian-Triassic boundary extinction 250 million years ago."

Given how things are frying from the Sun now, and this frying has been increasing rapidly over the last two years, I would contend that this sequence of events is already well under way, and is probably an unstoppable juggernaut of doom at this point.

And see how everything feeds into everything else. The oceans belch H2S. This destroys the hydroxyl radicals in the atmosphere, which would normally react away methane. But with the hydroxyl radicals destroyed, the methane lingers much longer, heating things up more, which makes more ferocious H2S plumes and melts more methane, making the ozone layer wither away yet more, adding yet more heat...and so on.

This is like a sickness upon the Earth that has to burn itself out before it gets better. This phase won't be done until all the methane has been released, the ozone layer is destroyed, and pretty much everything in the oceans and (to a lesser degree) on land is dead. I truly doubt that anyone on the surface of the Earth has more than five years left to live.