Really depends on what happens with phytoplankton; if they can adapt well enough to survive the excessive heat. Some of them can but others are dying out. If we lose all of them, then everything that breaths oxygen is extremely fucked since they make ~70-80% of that oxygen. Then we only have plants and forests like the amazon to make O^2^ (and we all know how that ones going), and then we would also have to deal with the gasses produced by all the oceans on the face of the earth dying and everything in them rotting... if they're not par-boiled.