> Bivalves grown under near preindustrial CO2 levels displayed thicker, more robust shells than individuals grown at present CO2 concentrations, whereas bivalves exposed to CO2 levels expected later this century had shells that were malformed and eroded. These results suggest that the ocean acidification that has occurred during the past two centuries may be inhibiting the development and survival of larval shellfish and contributing to global declines of some bivalve populations.
i'm not sure where the claim "all of the shellfish species that currently exist lived back then too" is coming from, although it is correct that CO2 was higher in the past (https://www.skepticalscience.com/co2-higher-in-past.htm)
Look at the study, not just the summary. What does "preindustrial levels" mean? Preindustrial includes over 4 billion years, including years with no life on earth. It includes the absolute highest and absolute lowest levels of atmospheric CO2 ever in the history of the planet. They chose a very low level that would give them the biggest results, and compared it to a hypothetical future level which isn't actually possible to achieve because there's not enough carbon stored in all the fossil fuels on the planet to get close to it if we burned every drop. Yes, record low atmospheric CO2 means shellfish have slightly thicker shells. Does that have an actual benefit for shellfish, much less entire global ecology? Those low CO2 levels are unquestionably bad for other things, like plants, and humans. Shellfish survived previous high CO2 levels just fine, we have the fossils, they existed. They can go ahead and have slightly thinner shells, while we have more plants and more food.
Also, we're talking about coral bleaching and it being blamed on CO2 despite absolutely no evidence, and despite the fact that some coral reefs are seeing normal growth, while others which are in major pollution streams from Asian rivers are seeing bleaching events. But it has to be CO2 because Al Gore says so! Ignore the billions of tons of toxic waste being pumped into the Ocean by China and India and Africa! Europeans and North Americans are the problem with their evil CO2! They need to become poor like everyone else to save the planet!
says:
> Bivalves grown under near preindustrial CO2 levels displayed thicker, more robust shells than individuals grown at present CO2 concentrations, whereas bivalves exposed to CO2 levels expected later this century had shells that were malformed and eroded. These results suggest that the ocean acidification that has occurred during the past two centuries may be inhibiting the development and survival of larval shellfish and contributing to global declines of some bivalve populations.
i'm not sure where the claim "all of the shellfish species that currently exist lived back then too" is coming from, although it is correct that CO2 was higher in the past (https://www.skepticalscience.com/co2-higher-in-past.htm)