Don't know if this site or its analysis of this study are reliable, this is just something I saw on Twitter. In fact I don't know if the study itself is reliable. I just think it would be morbidly funny if human driven climate changed wiped out enough of the major oxygen producing organisms to cause a reverse Great Oxidation Event.
God talking to humankind:
"Heyy you loving that oxygen? Pretty sweet isn't it? Wanna know how I did it? It's really clever, you're going to love this. See, at the beginning I crafted the rules that underpin everything, yadda yadda yadda, some bacteria in an anaerobic world gain crude photosynthesis and BAM, complex multicellular life is possible. Those godless scientists call it the G-O-E, it even kinda sounds like my name. You must be pretty grateful. I mean, without, you wouldn't exist or be around to ponder the nature of the universe and we wouldn't be talking. Ha ha—
Hey, what the fuck? Don't do that. Do not do that. No. You can't kill those. You cannot kill- well there they fucking go. Now I have to wait another six billion years for complex life to evolve somewhere else. This game sucks. It should be way more hands on. Can we re-enable divine intervention?"
The analysis is robust from my brief skim but comes to a different conclusion than "plankton face extinction", specifically:
That's still quite bad when 4 degrees of warming hits ecosystems all at once - for example this study didn't account for bleaching impacts on symbiotic foraminifera