Atmospheric conditions - what impact do they have?

[Jubala]

I beg to differ. To change a planets atmosphere you would most likey have to change the entire ecosystem. Just removing the gas you don't like (Methane) and inserting the gas you like (Oxygen) won't cut it as the planet ecosystem (plants and animals) will most likely reverse it. You'd have to introduce "your" plants and animals to replace the indigenous ones. Besides, changing the atmosphere should improve the conditions slightly as well. I sure as hell would think the conditions where better if I could breathe.