Eli has been spending some time over at Bishop Hill's talking the Salby. To be honest Frederick Engelbeen has been carrying the load, but Eli has been ducking in now and again. The issue, of course is whether pCO2, the pressure of CO2 above the oceans follows the temperature (Salby) or drives it (Everybunny sensible).
There are lots of reasons to hold that the Murray is wrong, not only the old standbys, but some new ones, which will be discussed in a following post, but something interesting (to Eli, but Eli is easily amused) about the fizzy coke effect came up, how useful is Henry's law for describing the equilibrium concentration of CO2 above the ocean given the complex equilibrium between CO2 in the gas phase and in the ocean, and the carbonic acid, H2CO3, the hydrogen carbonate ion, HCO3-, and the carbonate ions CO32-.
Henry's law states that the pressure of CO2 in the gas phase is related to the amount of CO2 dissolved in the liquid,
For most purposes, e.g. physical chemistry classes, k is treated as a constant. Not a bad approximation, but really is a function of temperature, T, and in the oceans, the salinity, S
k= exp [-60.2409 + 9345/T + 23.3585 log(T/100)]there is an app for that, which includes the nice figure to the right, the R code for the calculation and the applet, and a discussion of the chemistry involved with pointers to the original articles.
+ S [0.023517 - 0.00023656 T + 0.0047036 (T/100)2]
For this Eli has to thank Scott Denning at Colorado State and his group.
Runing the calculation at fixed alkalinity and dissolved inorganic carbon over a range of temperature more or less representative of what is found in the oceans shows that pCO2 varies pretty close to quadratically with temperature
pCO2(T) = k(T)[CO2(aq)](T)where all three terms are quadratic functions of temperature (ok, well approximated as quadratic functions, but R2 > .9997 for all three)
The oceans are non-linear fizzy coke.