To return to the subject of terraforming, can you remove gases, especially methane and oxygen?
The former should be possible using bugs or algae (specially tailored algae should do the trick), but the time frame may need to be speeded up. In fact it should be possible to remove methane and carbon dioxide while adding oxygen at the same time using such a system.
Removing oxygen should not be impossible ? higher oxygen pressure should mean combustion is pretty ferocious, and the addition of an easily oxidizable substrate to the atmosphere should enable you to bring the oxygen pressure to within your species tolerances.
Regards