Board Thread:Questions and Answers/@comment-90.244.94.220-20141004224535/@comment-4621372-20141022204743

Congratulations: you basically just turned the atmosphere into what it was a few 100 million years ago, during the Carboniferous era. Few differences, but nothing that's make much of a difference.

Makes it a LOT easier to be an insect or a fish. Makes it nigh on impossible to be a human, since the excess of oxygen would make us constantly giddy. But, that can't be sustained for long. It would fall down to around 30% O2 after a 100 million years or so, then stabilize there.