106 



BROECKER 



[CHAP. 4 



> l < ISOLATION 



DEEP 

 OCEAN") I 



— JL-J 



I 



HYPOTHETICAL 



INDUSTRIAL 



EFFECT 



400 300 200 100 



YEARS BEFORE PRESENT 



Fig. 10. A hypothetical example of the effects of non-steady-state mixing on the distribu- 

 tion of 14 C in the ocean-atmosphere system. One -hundred -year periods of very rapid 

 oceanic mixing are separated by 100-year periods during which no mixing occurs 

 between the upper 100 m of the ocean and the deep sea. The distribution of 14 C at 

 t = corresponds roughly to that of the present (corrected for industrial CO2 and 

 bomb 14 C). Note that 14 C data are given in A 14 C units (i.e. — 100 is equivalent to 

 0.900). 



1.030- 



o 0.990 



o 



o 



s 



8 0.980 



0.970- 



□ 



O i 



f 

 '<b° 



0°0 



AVERAGE EXPERIMENT 

 UNCERTAINTY 

 * 0.005 



D DEVRIES (1958) 



O WILLIS ETAL (I960) 



A BROECKER ET AL (1959) 



V 0STLUND (1957) 



O MUNNICH (1957) 



1700 1500 



1300 1100 900 700 

 CALENDAR DATE 



300 



100 100 

 AxfH.C. 



Fig. 11. Age-corrected 14 C results for tree-ring and historically dated samples of various 

 ages. The results place limits on the temporal variation of the 14 C/ 12 C ratio in atmos- 

 pheric CO2. 



