Never thought of it that way. Could be an interesting experiment.
However, as Carbon Monoxide is not on the naughty list for global warming, a properly controlled experiment would need to eliminate that and other non global warming related gases. Toxic or not. Then, you would also need to remove the humans as they, also, would emit carbon.
This is where the carbon argument is all awry. We may eliminate all carbon related global warming and still be left with a world where only toxic gasses exist.
The argument is so much more convincing when the words are in pictures.
Sadly, methinks you are flogging a dead bovine.
I still remember what it was like accessing a text based BBS using a 2400bps dial-up modem on a 286 PC running MS-DOS. If we had filled the bandwidth with all the cr*p that we have today, it would have taken about an hour just to say hello.
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"No friend ever served me, and no enemy ever wronged me, whom I have not repaid in full."