In particular, recent studies have shown that more atmospheric CO2 is causing the PH
of ocean surface layers to drop (ie become more acidic) leading potentially to coral kills and substantial changes in sea life.
This suggestion is motivated by the intention of avoiding an aragonite undersaturation in
the ocean surface layer.
If the temperatures had been above average, there would have been more surface melt and heating of
the ocean surface layer; this would have accelerated the melt rate of the ice.
Thus the pH level of
the ocean surface layer is not the same thing as the total CO2 dissolved by the oceans.
Inspection of dT / dt may give useful insight into the net power entering or leaving
the ocean surface layer.
However, I have repeatedly pointed out that the opposite is also possible because the deep ocean waters now returning to ocean surface could be altering the pH of
the ocean surface layer with resulting release of CO2 from the ocean surface layer.
A main indirect effect is the fertilization of ocean phytoplankton production by dust - mitigated input of iron to
the ocean surface layer (6, 7).
Thus your model doesn't fit one of the basic observations of what happens in the atmosphere and
ocean surface layer (which also shows a similar decline).