Marine life is being destroyed, including plankton, and it would be reasonable to expect that oceanic oxygen production has declined as a result, something the "experts" don't necessarily highlight. This could be related to rising ocean temperatures or not. I don't know. Trying to peer through the deceptions makes my head hurt and I just want to take a nap. That's an intended effect.
I think I read 30 years ago that 90% of our oxygen comes from photosynthesis by algae in the water.
I pulled the 50% figure from NOAA. We have our choice of deceptions. They say that plankton include algae among other things, and claim that marine life consumes the oxygen produced there. (See https://oceanservice.noaa.gov/facts/ocean-oxygen.html -- read this site like you were reading a work of fiction. Also see https://www.britannica.com/science/plankton.)
Marine life is being destroyed, including plankton, and it would be reasonable to expect that oceanic oxygen production has declined as a result, something the "experts" don't necessarily highlight. This could be related to rising ocean temperatures or not. I don't know. Trying to peer through the deceptions makes my head hurt and I just want to take a nap. That's an intended effect.