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

Fri Dec 17 10:58:34 PST 2010

If I understand correctly, coral reefs can remove carbon from ocean
water, but in total, some scientists insist, emit CO2 into the
atmosphere, though the complexities of all the organisms associated
with coral reef communities must be considered; and this is part of
the reason there has been a debate on this question, as the scientific
sources quoted below indicate.

Now I wonder, if coral reefs remove carbon from ocean water, do they
help to lower ocean water accidification from human sourced CO2
emissions?

Tom Goreau, President, Global Coral Reef Alliance, wrote:

http://coral.aoml.noaa.gov/pipermail/coral-list/2007-December/005082.html

"Not only is the entire claim that coral reefs are a CO2 sink completely
incorrect, they are in fact a source of CO2 to the atmosphere even while they
remove carbon from the ocean."

On 12/17/10, Ted Moffett <starbliss at gmail.com> wrote:
> As is sometimes the case with scientific issues, answering a given
> question can result in uncovering uncertainty and complexity.  Some
> seemingly credible sources indicate quite divergent evidence.  When
> surveying all the scientific literature on a given question, if there
> is widespread disagreement, it is reasonable for a layperson to
> consider the question still under investigation.
>
> On the question of whether coral reefs are atmospheric carbon sinks or
> emit carbon into the atmosphere, there has been debate in the
> published science.  Finding the most recent scientific publications
> regarding this question might reveal a more certain answer to the
> question, given the more recent science should correct previous
> potential scientific errors or omissions.
>
> Some of the following scientific publications make reference to a
> "debate" on this issue, so this indicates that indeed there has been
> disagreement in the scientific community on this question.
>
> Maybe at this point in time the debate has been mostly resolved.
>
> I have not surveyed enough of the scientific literature to feel
> confident about answering this question, in part because I am not sure
> exactly how to frame the question, given the complexities of coral
> reef communities.  If I read the literature correctly, calcium
> carbonate formation must be considered, along with the organisms that
> the reef supports, to analyse the carbon cycle.  Some coral reefs
> might be carbon sinks, others not.
>
> Below are some scientific sources I found in a brief search.
>
> This first source contains an argument from Tom Goreau, President,
> Global Coral Reef Alliance, quite emphatically arguing that coral
> reefs are not carbon sinks for atmospheric CO2:
>
> [Coral-List] Climate change and coral reef sequestration of carbon
>
> http://coral.aoml.noaa.gov/pipermail/coral-list/2007-December/005082.html
>
> My comment:
>
> One way or the other regarding this question, the science indicates
> coral reefs impact on the carbon cycle influencing atmospheric CO2
> level for the time scale (a couple of centuries) in which the hundreds
> of billions of tons of CO2 from human emissions are being dumped into
> our atmosphere, is minimal.  One of the sources below claims coral
> reef emissions of CO2 into the atmosphere are a mere .4 to 1.4 percent
> of anthropogenic CO2 emissions.
> ---------------------------------
>
> http://www.pnas.org/content/95/11/6566.full?related-urls=yes&legid=pnas;95/11/6566
>
> Anomalies in coral reef community metabolism and their potential
> importance in the reef CO2 source-sink debate
>
> John R. M. Chisholm * and David J. Barnes
>
> Overall, reef growth may serve to drive CO2 into the atmosphere but
> probably to a lesser extent than has been indicated by Lagrangian
> measurements of reef flat metabolism at Moorea (31 mmol per m2 per
> day) and Yonge Reef on the GBR (182 mmol per m2 per day) (6).
> Comparative studies using a Eulerian approach indicated rates of CO2
> efflux that were lower by 1–2 orders of magnitude (1.81 mmol per m2
> per day at Moorea and 5.1 mmol per m2 per day at Yonge) (9). If these
> latter data are the more representative, then inclusion of high net
> organic productivity on the seaward slopes of reefs (30) may indicate
> that whole reefs act as sinks for atmospheric CO2. The fact that
> carbonate rocks store 3 × 104 more inorganic carbon than the
> atmosphere (17) shows that reefs are sinks for CO2 over geological
> time.
>
> ------------------------------
> http://www.pnas.org/content/96/23/13017.full.pdf
>
> Measurement of Community Metabolism and Significance in the Coral Reef
> CO2 Source-Sink Debate
> ------------------------------
> http://www.sciencemag.org/content/269/5221/214.abstract
>
> Science 14 July 1995:
> Vol. 269 no. 5221 pp. 214-216
> DOI: 10.1126/science.269.5221.214
>
> Diurnal Changes in the Partial Pressure of Carbon Dioxide in Coral Reef
> Water
> Hajime Kayanne, Atsushi Suzuki and Hiroshi Saito
>
> Coral reefs are considered to be a source of atmospheric carbon
> dioxide because of their high calcium carbonate production and low net
> primary production. This was tested by direct measurement of diurnal
> changes in the partial pressure of carbon dioxide (Pcoco2) in reef
> waters during two 3-day periods, one in March 1993 and one in March
> 1994, on Shiraho reef of the Ryukyu Islands, Japan. Although the
> Pcoco2 values in reef waters exhibited large diurnal changes ranging
> from 160 to 520 microatmospheres, they indicate that the reef flat
> area is a net sink for atmospheric carbon dioxide. This suggests that
> the net organic production rate of the reef community exceeded its
> calcium carbonate production rate during the observation periods.
> --------------------------------
> http://www.springerlink.com/content/g2r13h6u35p76763/
>
> Coral Reefs
> Volume 11, Number 3, 127-130, DOI: 10.1007/BF00255465
> Coral reefs: sources or sinks of atmospheric CO2?
> John R. Ware, Stephen V. Smith and Marjorie L. Reaka-Kudla
>
> Abstract
>
> Because the precipitation of calcium carbonate results in the
> sequestering of carbon, it frequently has been thought that coral
> reefs functions as sinks of global atmospheric CO2. However, the
> precipitation of calcium carbonate is accompanied by a shift of pH
> that results in the release of CO2. This release of CO2 is less in
> buffered sea water than fresh water systems; nevertheless, coral reefs
> are sources, not sinks, of atmospheric carbon. Using estimated rates
> of coral reef carbonate production, we compute that coral reefs
> release 0.02 to 0.08 Gt C as CO2 annually. This is approximately 0.4%
> to 1.4% of the current anthropogenic CO2 production due to fossil fuel
> combustion.
> ------------------------------------------
> Vision2020 Post: Ted Moffett
>
> On 12/16/10, nickgier at roadrunner.com <nickgier at roadrunner.com> wrote:
>> Good Morning Visionaries,
>>
>> Sam Scripter was kind enough to point out an error in my column on climate
>> change. Contrary to what many people think, coral reefs do not act as
>> carbon
>> sinks. On balance they are carbon emitters.
>>
>> Too late to correct for the Sandpoint Reader (I'll send a letter), but I
>> can
>> change it for the Idaho State Journal and Los Cabos Daily News, and of
>> course my website.
>>
>> As I said with regard to creation scientists and climate change deniers:
>> "The willingness to correct errors always increases the credibility of
>> those
>> whom we want to believe.  Only ideologues believe that finding errors or
>> conceding them are fatal weakness."
>>
>> Thanks, Sam.
>>
>> Nick
>>
>> --that corals must take carbon out of the a---- Sam Scripter
>> <MoscowSam at charter.net> wrote:
>>> Nick . . .
>>>
>>> Did Ted or anyone else point out the error below to you?
>>> Have you already "gone to press"?
>>>
>>> Sam Scripter
>>>
>>> You wrote:
>>>
>>> Warmer and more acidic seas destroy coral reefs,
>>> which, under normal conditions,*take tons of
>>> calcium  out of CO2.*  About 80 percent of the corals
>>> at the eastern end of the Indonesian island of
>>> Sumatra are now dead.
>>>
>>>
>>> Here is a paragraph from Wikipedia about "coral":
>>>
>>> Coral's narrow niche <http://en.wikipedia.org/wiki/Ecological_niche> and
>>> the stony corals <http://en.wikipedia.org/wiki/Scleractinia>' reliance
>>> on calcium carbonate <http://en.wikipedia.org/wiki/Calcium_carbonate>
>>> deposition makes them susceptible to changes in water pH
>>> <http://en.wikipedia.org/wiki/PH>. The increase
>>> in atmospheric carbon dioxide has caused enough dissolution of carbon
>>> dioxide to lower the ocean's pH, in a process known as ocean
>>> acidification <http://en.wikipedia.org/wiki/Ocean_acidification>.
>>> Lowered pH reduces corals' ability to produce calcium carbonate, and at
>>> the
>>> extreme, can dissolve their skeletons. Without deep and immediate cuts in
>>> anthropogenic CO_2 , many scientists fear that acidification will
>>> severely
>>> degrade or destroy coral ecosystems.^[28]
>>> <http://en.wikipedia.org/wiki/Coral#cite_note-Gattuso-27>
>>>
>>> http://en.wikipedia.org/wiki/Coral
>>>
>>> nickgier at roadrunner.com wrote:
>>> > Warmer and more acidic seas destroy coral reefs, which, under normal
>>> > conditions, take tons of calcium out of CO2. About 80 percent of the
>>> > corals at the eastern end of the Indonesian island of Sumatra are now
>>> > dead.
>>> >
>>
>>
>
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