Shells are constantly replenishing with more CO2 needed. It is just another scare tactic, supported partly by experiments of dumping acid. CO2 is not an acid. You would think climate scientists would understand basic things like that. Instead confirmation bias, leads them to run with whatever story supports their cause rather than being skeptical as they llike to tell us all true scientists are.

Crustaceans have exoskeletons of chitin which is kind of a sugary / protein compound. It isn't like corals and some plankton that may produce CaCO3 (calcite, aragonite, etc)

http://en.wikipedia.org/wiki/Chitin

In fact, they have done studies and it seems clear that corals do very well in very warm water. They may have to purge their zooanthalae (the algae in their bodies that feeds them) and incorporate zooanthalae that are adapted to greater temperatures or other conditions. The corals use photosynthesis to power the conversion of carbon compounds into carbonates in the skeletons. Coccolithifers (I am sick today and I just can't seem to remember how to spell these things) are the same.

With increasing carbon compounds in the ocean, alarmists would like you to believe that makes it harder for the marine creatures to use that carbon. I think, as with many issues, they are grasping at straws. I think the lowered pH (and it would be miniscule) would be more than compensated by available dissolved carbon.

I would be curious if Pegminer could provide a scientific study showing that increased acidity in the small amounts we are talking about, harms chitinous organisms.

Ho hum, obviously the time it would take is not calculable because the ocean isn't a closed system. As more CO2 was added in the past to the ocean, it precipitated in the oceans forming vast formations of carbonates and it was also removed by corals and other calcium producing organisms. Alarmists try to rewrite geologic history and suggest that what happened before won't happen this time because this time humans are emitting the CO2. I find their level of argument to not reach nonsense levels. It is more like WTF are you talking about levels.

I don't think they try to "assume" anything, there are laboratory and in situ studies that indicate that many marine organisms will have problems with decreasing pH. There are other organisms that probably won't, at least in the near future.

The volume of the ocean is large, but on the short time scale the CO2 is not being mixed throughout the entire ocean, so the change will be relatively fast. You can estimate yourself from a graph like this:

http://www.pmel.noaa.gov/co2/file/pH+Tim...

Or since we know that at present the pH is changing about 0.002/year, for a change of 0.1 it will take

0.1/(0.002/year) = 50 years.

Of course that rate would be expected to accelerate with increasing CO2 in the atmosphere.

EDIT: Kano, you should apply for a job, clearly you know more about the subject than those doing the research.

Washington oyster growers aren't "assuming" there's a problem, they saw massive failure of oyster spat and have had to institute pH controls in their nursery operations to deal with the problem.

Your claim that we can't measure pH accurately is BS

The attached links are interesting.

You also need to read up on "buffers". Acidity does not necessarily change in the way you might expect.

http://www.chemguide.co.uk/physical/acid...

Hmmm