SUMMARY AND ENVOI 



DANIEL A. LIVINGSTONE 



Department of Zoology, Duke University, Durham, North Carolina 



The life of a subject can be measured by the turnover time of its ideas, the 

 length of time it takes for half of what is taught to beginning students to become 

 completely worthless. On such a scale the geochemistry of carbon has a half-life 

 of something between 10 and 15 years. A few problems, a datum or two, remain 

 of what I learned about it from Professor Hutchinson 20 years ago, but little 

 else. Cosmology, geophysics, and molecular biology turn over a little faster, but 

 10 or 15 years is quite respectable and places the biogeochemistry of carbon 

 well up among the livelier branches of science. 



The summary speaker at a symposium like this is supposed to function as a 

 high-speed shipwright. He hopes to have delivered to him by the participants in 

 the symposium a sufficient number of sound planks and properly hewn timbers 

 that he can peg together in the last few minutes of the last contributor's talk and 

 present to the audience as a vessel of sorts, a skiff or even a sloop, in which they 

 can sail away on the voyage implied by the envoi of George Woodwell's title for 

 these concluding remarks. 



Looking back over the papers delivered here during this symposium, I recall 

 a number of very careful and clear expositions of the elements of the subject; I 

 also recall a number of accurate analyses of carbon systems ranging from 

 microscopic calcite crystals through forests to the atmosphere of the entire 

 earth. There have been valuable and well-balanced reviews of several broad 

 aspects of the carbon cycle and original theoretical and observational studies 

 dealing with them. Looking over this wealth of materials, however, I can see no 

 way of fitting the separate contributions together into an integrated structure. 

 These contributions include some bright and shiny new nails, a few odd strakes 

 and sawn frames, and at least two complete vessels, a Deevey schooner and a 

 Broecker full-rigged ship. If you feel like cruising, you will have to use one of 

 them. 



William Reiners suggested that a further office of the giver of concluding 

 remarks was to present society at large with some clues on how to handle the 



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