Geology/Cliamtology - Co2 absorbtion by oceans - can you help ?

[gustard33]

In the real world, as measurable by science, CO2 in the atmosphere and in the ocean reach a stable balance when the oceans contain 50 times as much CO2 as the atmosphere. ‘The IPCC postulates an atmospheric doubling of CO2, meaning that the oceans would need to receive 50 times more CO2 to obtain chemical equilibrium,’ explains Prof. Segalstad. ‘This total of 51 times the present amount of carbon in atmospheric CO2 exceeds the known reserves of fossil carbon – it represents more carbon than exists in all the coal, gas, and oil that we can exploit anywhere in the world.’

I find this statement quite hard to understand. I cant see how he gets from Atmospheric doubling to 50 times the amount of CO2. If the ocean has 50 times the amount of CO2 then surely doubling the atmospheric CO2 would just double the oceanic CO2 not multiply it by 50. Not even that actually as the oceans absorb more the figure would be less. Plus it seems unlikel;y that pumping CO2 into the air very quickly would suddenly, magically, cause the oceans to double their CO2 . Also the ocean can absorb different amounts depending on its temperature - so the more CO2 in the atmosphere or ,even if you do not accept AGW, the warmer it gets - the less the oceans can absorb .

Then he arrives at this figure of 51 - Im really confused can someone explain this to me ?

[Mr Skeptic]

Well, assume for now that his statement about the ocean holding 50 times the CO2 as the atmosphere is correct (that is the only questionable thing here, and at the very least is inaccurate). Then, to double the amount of CO2 in the atmosphere (allowing the ocean to reach the same equilibrium) would double the amount of CO2 in the ocean -- which he claims will have 50 times the CO2 as the atmosphere. So 1 + 50 = 51.

 

His math is fine. I doubt his assumptions are, especially since warming will reduce the amount of CO2 that can be absorbed, and it is likely that dissolved ions in the water have something to do with the amount of CO2 in the ocean, in which case his assumption is wrong. In any case, acidifying the ocean as carbonic acid (dissolved CO2) would, would oppose additional CO2 dissolving, as well as being nasty to marine life.

[gustard33]

His math is fine. I doubt his assumptions are, especially since warming will reduce the amount of CO2 that can be absorbed, and it is likely that dissolved ions in the water have something to do with the amount of CO2 in the ocean, in which case his assumption is wrong. In any case, acidifying the ocean as carbonic acid (dissolved CO2) would, would oppose additional CO2 dissolving, as well as being nasty to marine life.

 

Thanks - another thing I dont understand is that I dont understand why just because you double the atmospheric CO2 that means it automatically doubles the oceans CO2. Is this a given ? We are pumping lots of CO2 into the atmosphere - it doenst make sense that it has to see a reflected rise in ocean automatically and immediately - maybe there will simply be no equilibrium. There just seems to be a logical fallacy there - either the ocean will absorb the escess CO2 or it wont. If it is saturated then surely it will just stay in the atmosphere making the 50 times figure inaccuirate.

[Mr Skeptic]

Thanks - another thing I dont understand is that I dont understand why just because you double the atmospheric CO2 that means it automatically doubles the oceans CO2. Is this a given ?

 

I doubt that it does. If it was pure water I think it would though.

 

We are pumping lots of CO2 into the atmosphere - it doenst make sense that it has to see a reflected rise in ocean automatically and immediately - maybe there will simply be no equilibrium.

 

So long as we are emitting CO2, then there can be no equilibrium. It takes time for the CO2 to dissolve, especially if it is to dissolve in the entire ocean rather than just the top. I think that we're talking centuries there.

 

There just seems to be a logical fallacy there - either the ocean will absorb the escess CO2 or it wont. If it is saturated then surely it will just stay in the atmosphere making the 50 times figure inaccuirate.

 

Gases in liquid solutions don't behave as solids in liquid solutions. If you increase the partial pressure of a gas (by increasing the concentration or the total pressure), then the amount that dissolves in the liquid at equilibrium will increase. If the dissolved minerals in the ocean are involved in this, it won't be so simple though.