Thanks, I'd never really considered the impacts climate change would have on oxygen. I looked into this a bit and it seems to also be the case that rising ocean temperatures also reduce the capacity of the water to hold dissolved oxygen, which causes a nasty feedback loop.

So while there's not an immediate risk of atmospheric oxygen concentration dropping by any significant amount, there is a real concern of oxygen concentrations in the oceans dropping pretty drastically. This then accelerates climate change even further and could have longer term effects on atmospheric levels as well.