Letter from Thomas Gold to Dr Richard Garwin, T J Watson Research Center, IBM Corporation, PO Box 218, Yorktown Heights, New York States the enclosed may interest Garwin, as he has concerned himself with energy matters, The geologists do not seem to have really given much thought to the problem of the origin of terrestrial carbon. States the recent NRC announcement that the continued use of fossil fuels may result in some dramatic and disastrous climatic change runs counter to Gold's views - the unknown natural source of CO2 is most unlikely to be so steady that its fluctuations would not greatly overshadown the man-made effects. There is just as good a chance that wey ought to do our best to make up a natural deficiency as to avoid an excess - we cannot tell. 25 July 1977