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

[Ted Moffett]

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
>