[acetofenone]

My main concern is the acidification of the ocean due to the carbon dioxide equilibrium between the atmosphere and the sea. There is a threshold level threshold at wich the shell of plankton just dissolves. After that happens I think the whole ocean ecosystem will collapse (maybe no more fishes?) Also the deep ocean has an inertia of thousands years meaning that we are going to stick with industrial coal revolution levels of co2 in the atmosphere for a lot of time even if we emit nothing.

People wasn't seeing immediate effects because it was hidden in saturating the ocean and now there's no way back in my opinion

[asah]

Competing species (non-calcifying) then take over...

[M95D]

What you probably don't know yet is that ocean calcifying organisms are the only ones left that still remove CO2 from the atmosphere long term.

Trees take CO2, but when they die, bacteria and fungi oxidize the wood back to CO2. Same for everything else that's greenwashed as "removing CO2". That removal is temporary - only a few years or decades at most.

Without the oceans to trap CO2 into new limestone deposits, we're doomed and we can do absolutely nothing about it.

[rstuart4133]

It's not the only mechanism for CO2 removal. There is also a geo cycle. I've forgotten the exact details, but it involves the acidity created by CO2 increasing the speed of rock weathering, and the result sediments being incorporated into the plates, plate tectonics removing the carbon from the upper crust and volcanoes re-introducing it. It's self regulating but very slow, taking millions of years.

Granted, biological removal is much faster, now. But during snowball earth in particular there was so little biological activity the geo cycles dominated CO2 regulation.

Neither of those two mechanisms are relevant right now, as mankind's production of CO2 has swamped both mechanisms. That will stop one way or another of course.

[consumer451]

Will those species replace plankton's role of producing the majority of the Earth's oxygen?

[bryanlarsen]

After a few million years, sure.