[Vision2020] Clarification: Re: Coral Reefs: CO2 Source or Sink? Re: Four Levels of Global Warming: A Climate Change Update

[Sam Scripter]

Since Nick's piece, with a sentence or so about "coral", I have been 
following
the ensuing discussion regarding ocean acidification and coral.

But I am puzzled.

Maybe that's because I am not on top of the changing views of "science"
about the dangers of ocean acidification, caused by carbon dioxide 
increasingly
dissolving into oceans' waters, from an increasing concentration of carbon
dioxide in the atmosphere [anthropogenic or not].

I thought -- until recently at least -- that the concern for coral, and 
for shellfish
at large, was that the chemical shift to increasing acidity in the 
oceans was feared
to dissolve the shells of some shellfish and  perhaps even prevent 
formation of
shells in other shellfish trying to live.

E.g., some or many shellfish could be put out of existence, "screwing 
up" some
ecological food chains as well as sources for human food. These are not 
small
matters!

Am I off base? Has that concern gone away and/or shown to be false alarms?

Or are Nick and the ensuing discussants in particular just choosing to focus
on whether coral is/are participants in chemical balance repositioning among
atmospheric, oceanic, and coral carbon?

Sam Scripter

Ted Moffett wrote:
> Thanks for the response to my question from the post which can be read
> in full at the website below, which will offer more context:
>
> http://mailman.fsr.com/pipermail/vision2020/2010-December/073255.html
> --------------------------
> I have found credible scientific information that relates to my
> question regarding coral reefs lowering ocean water acidity, though
> this information does not address coral reef calcium carbonate
> formation effects on ocean water acidity.  It addresses the
> dissolution of calcium carbonate in the oceans, lowering ocean
> acidity.  Calcium carbonate is a treatment for acid stomach.  But this
> process in the oceans is too slow to stop increasing ocean
> acidification from billions of tons of human CO2 emissions:
>
> http://www.elcamino.edu/faculty/tnoyes/Readings/10DR.pdf
>
> > From website above:
>
> "Recall that additional carbon dioxide makes ocean water acidic, and
> that the acid dissolves calcium carbonate ...this neutralizes the acid
> (the carbonate absorbs it). ...coral are said to "buffer" the ocean."
>
> This academic source also states "...corals 'permanently' remove CO2
> from the atmosphere by building their reefs" a statement that could be
> used to conclude that coral reefs are in total atmospheric CO2 sinks,
> which is disputed.
> ------------------------
> http://www.whoi.edu/OCB-OA/FAQs/
>
> > From website above:
>
> As the oceans become more acidic, more calcium carbonate minerals
> underwater will dissolve. Will that offset ocean acidification?
>
> The dissolution of calcium carbonate minerals in the water column and
> in the sediments does increase the alkalinity of seawater, which
> offsets the decreased pH and carbonate ion concentrations associated
> with ocean acidification. However, as with rock weathering, this
> process is slow and would take thousands to tens of thousands of years
> to neutralize all of the CO2 from human activity that is entering the
> oceans. Over the decades to centuries that affect human communities,
> these processes are not fast enough to counteract CO2 invasion into
> the ocean, and so the chemical changes associated with ocean
> acidification will last for several centuries. — Richard A. Feely,
> Senior Scientist, NOAA Pacific Marine Environmental Laboratory, USA
> ------------------------------------------
> Vision2020 Post: Ted Moffett
>
> On 12/17/10, Andreas Schou<ophite at gmail.com>  wrote:
>    
>>> Now I wonder, if coral reefs remove carbon from ocean water, do they
>>> help to lower ocean water accidification from human sourced CO2
>>> emissions?
>>>        
>> Not really. Coral reefs remove carbon from ocean water by constructing
>> their calcium carbonate exoskeletons; calcium ions, rather than
>> carbonate ions, create a bottleneck w/r/t how much carbon they can
>> remove.
>>
>> -- ACS
>>
>>      
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