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

Paul Rumelhart godshatter at yahoo.com
Sat Dec 18 15:09:25 PST 2010

I have read about this, too.  I don't know what to think about the 
effects of ocean acidification on coral reefs.  Scientists paint a bleak 
picture about rising CO2 levels, ocean warming, and the effects on 
coral.  On the other hand, coral has been around in one form or another 
since Precambrian times, 500+ million years ago.  During that 500+ 
million years, the CO2 levels have been as high as 4500+ ppm (we're at 
around 387 now, iirc), and the temperatures have been as high as 10 C 
higher than they are now in that same time period.  Geologically 
speaking, CO2 levels are dangerously low right now.  That doesn't mean 
that coral will have no problems, but it does give me hope that coral 
reefs will adapt to changing climate conditions just as they have in the 

I would be more concerned about new threats to coral that humans have 
brought, such as water pollution, sediments from construction, mining, 
logging, etc, coral mining, the effects of tourism on coral reefs, and 
so forth. 


Sam Scripter wrote:
> 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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