The acidification of the ocean is proportionate to the amount of carbon dioxide humans are pumping into the ocean. Once the ocean reaches a precipice of being saturated with carbon dioxide, the effects are catastrophic. Once the threshold is breached, earth scientists say it doesn’t matter how. Scientists are developing models to predict how the earth is going to respond, once the threshold is breached. Shells in the sea use carbon dioxide to build their homes. Too much or the wrong type and the sea creatures needing carbon dioxide can’t build their homes. Materials that aren’t used continue to build up and sink in the ocean. This creates a cascade effect further acidifying the ocean. Scientists theorize, once the threshold is breached, the earth takes over and determines the response.
https://phys.org/news/2019-07-breaching-carbon-threshold-mass-extinction.html