As mosquito's home in on CO2, the easiest route is to place updrafts of CO2 in localised areas (all over the place pretty much). It's hard to home in on people if there is a nearby CO2 updraft or it varies at random continuously.
The concentration doesn't even need to be high - just enough (and close enough together) to make prey detection impractical at any range. So it doesn't have to even be lethal to mosquitoes.
This isn't an issue for you, your guests, global warming/climate, or any non-bloodsucker. The only critturs attracted specifically to CO2 will almost by definition be those locating prey by their breath, which is basically bloodsucking insects looking for larger beings. Other insects might be affected by CO2, but the concentration would be low, so it wouldn't be lethal - and the amount of time an insect spends in a CO2 updraft would be linked to its bloodsuckerness - non bloodsuckers only enter updrafts at random, and leave them at random, so they get below average exposure even among all insects. Dedicated bloodsuckers on the other hand may be drawn to the updrafts but can't find prey within a varying environmental level of CO2.
Humans and mammals of course aren't likely to be affected at all. Even exhaled air contains considerable oxygen, and a higher level of CO2 isn't a problem - if needed the level of O2 could be raised slightly, the same way, which would benefit humans and animal life, but give no benefit or encouragement to bloodsuckers. The environment of course won't be affected - on a global scale any amount used will be microscopic in the context of other sources.
A sub-ground distribution mesh based on dry ice or another source, randomised oscillating (both direction and on-off) fans/valves, and perforated pipework directed upward, might be all it needs. You and all you love, including non blood suckers,will feel little beyond normal, and you can admire the mosquitoes as they fly around wondering where the hell their prey is ;-)