At the top of this board muso has a tread on the likely effects of increasing  CO2 and trots out "calcification" requirements of corals and shellfish. So the argument goes up goes CO2 and shells have much lower ability to utilize calcium or their shells get thinner or can't be formed at all and certainly would not be preserved in such an acid environment. muso also states that the tread would be limited to what is known rather than what "lurks around the corner"
In line with this surely the fossil record then for times that had much greater CO2 than the historically low concentration we have now would be devoid of shells or these would be much, much thinner. So wouldn't the non-existence of existence of these comprise what is "known"?

I say lets all pray to gaia that a little bit more warming does happen so the ocean may rise and cover those poor little critters living on coral reefs.

About the acidification, we have had warmer periods in our history and coral reefs survived.

namnugenot wrote on Nov 1^st, 2013 at 11:05am:


It's a question of which mineral the organisms are geared up to produce. Some, like most crustaceans, will survive quite happily under higher CO2 levels. It's quite correct that some  biota will be unaffected, however the ones that will be affected include (shallow) corals and many fish (their otoliths in particular)

Aragonite is the more soluble mineral. As temperatures have cooled, more organisms have evolved that produce aragonite. In the geological past there was more calcite. Aragonite is stable in colder climates whereas calcite is stable in warmer climates. 

Coral, particularly shallow coral is particularly affected by reducing ocean pH. Eocene corals were mostly totally different species from those of today.

http://link.springer.com/article/10.1007%2Fs00338-008-0375-6

I hope that addresses your question.