[Coral-List] CO2 in tropical oceans

[Thomas Goreau]

I fully agree with John Ware that if CO2 increases enough in the  
atmosphere one will eventually have more in equilibrium in ALL surface  
waters, but the fact is that tropical waters have MORE CO2 than the  
atmosphere, and this will continue even as atmospheric CO2 increases  
because this is driven by the fundamental fact that CO2 is more  
soluble in cold waters and by the temperature difference between polar  
and equatorial waters.

> Thomas J. Goreau, PhD
> President, Global Coral Reef Alliance
> Coordinator, United Nations Commission on Sustainable Development  
> Partnership in New Technologies for Small Island Developing States
> 37 Pleasant Street, Cambridge MA 02139
> 617-864-4226
> goreau at bestweb.net
> http://www.globalcoral.org

> Message: 6
> Date: Wed, 11 Feb 2009 14:43:35 -0500
> From: John Ware <jware at erols.com>
> Subject: [Coral-List] CO2 and tropical waters.
> To: "coral-list at coral.aoml.noaa.gov" <coral-list at coral.aoml.noaa.gov>
> Message-ID: <49932A67.5050500 at erols.com>
> Content-Type: text/plain; charset=us-ascii; format=flowed
>
> Dear List,
>
> I agree with much of what Thomas Goreau has written (see below), but I
> do not agree about his implication that tropical surface waters can
> continue to be a source of CO2 as BOTH temperature and pCO2 increase.
>
> Surely logic would lead one to conclude that, at the very least, CO2
> emissions from warm tropical surface waters must decrease at  
> atmospheric
> partial pressure of CO2 increases.
>
> To put the argument in concrete terms, suppose, just for the sake of
> discussion, that the warm surface waters were in equilibrium for
> atmospheric CO2 for CO2 at 275 ppmv, salinity 33 ppt, temperature 30  
> oC.
> My computer program indicates that dissolved inorganic carbon (DIC) is
> about 2.75 mM/L at a pH of 8.449.  (Your computer program will  
> probably
> give different answers because we use different constants or slightly
> different computational methods.  However, what counts is not absolute
> values, but differences.)
>
> Now, suppose nothing else happens but that pCO2 doubles to 550 ppmv.  
> DIC
> increases by 23% to 3.37 mM/L and pH decreases by about 0.2 units to  
> 8.27.
>
> Of course, global warming would increase water temperature and the
> solubility of  CO2 would decrease.  So, by how much would temperature
> have to increase to offset the increase in DIC due to increased pCO2?
> The answer is over 10 Co to approximately 40 oC!!  (In fact, my  
> program,
> which could be wrong, indicates a temperature increase to 45 oC.)
>
> And, of at least equal importance, the pH stays almost the same as the
> temperature increases, so the acidification due to increased pCO2 is  
> NOT
> affected by the increase in temperature.
>
> Now, a lot of assumptions go into this type of calculations, and I  
> would
> appreciate my conclusions being confirmed or rejected if they are  
> wrong.
> However, the confirmation or rejection should be based upon
> calculations, not hand waving arguments.
>
> John
>
> P.S. On slightly different, but related, topic.  The recent paper by
> Solomon et al (PNAS, 2009, 106:1704-1709) shows that, even if
> anthropogenic CO2 emissions were to magically go to zero instantly,  
> the
> effects continue for at least 1000 yrs.
>
> J
>
> -- 
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