102 



BACASTOW AND KEELING 



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C0 2 INCREASE (1959 TO 1969), % preindustrial atmosphere 



Fig. 6 Adjustment of the six-reservoir model with an increasing land biomass 

 to fit preassigned values of the Suess effect relative to standard, Su4 8 , and 

 1 4 C/C ratio in ocean water, R m /R # , relative to the oxalic acid standard for the 

 year 1954. Su 48 varies from -1.6 to -2.3%; R m /R # = 0.999. Curves show the 

 variation in the predicted C0 2 increase in the atmosphere between 1959 and 

 1969 as j3 varies for fixed values of r am and N mo /N ao . Su 48 varies only 

 negligibly for different values of (5 along a given curve. A small heliomagnetic 

 effect (approximately —0.03%) has been included in the Su 48 evaluations. 



adjusting T am , N m0 /N a0 , and j3 to produce a prescribed value of Su 48 , suggest 

 that at present we cannot very precisely fix the size of the ocean surface layer 

 from a knowledge of the Suess effect: to specify N m0 /N a0 within ±30% of its 

 value would require that the Suess effect be known to ±0.05%. We may instead 

 take the point of view that the model restricts the predicted value of the Suess 

 effect if we require a reasonable value of N m0 /N a0 . On the basis of general 



