IS THERE INTELLIGENT LIFE ON EARTH? 269 



the birth rate, or decrease per capita consumption. I think it is also clear that, 

 given the choice in those terms, the fact that rates of population growth have 

 not already fallen to bare replacement levels is evidence that not enough people 

 are able to exercise the choice or that not enough of them understand the choice 

 to be made. 



Let me tell you where we stand now, with reference to population and 

 consumption. As late as the year 1950, when more than one-third of the world's 

 present population and one-quarter of that of the United States was not yet 

 here, the imminence of the problems now facing us was not at all clear. A few 

 farsighted people saw difficulties ahead, but to most people it seemed that there 

 was plenty of room not only in North America but elsewhere in the world, 

 plenty of resources, and no great hazard to the environment. Since 1950 the 

 U. S. population has grown by about 56 million — the gross national product 

 (GNP), which was then $400 billion, has increased by two and one-half times to 

 a trillion dollars in 1971, and solid wastes have reached a total of about 4 billion 

 tons/year. About 400 million tons of these solid wastes are urban — a great 

 mixture of trash, paper, tin, garbage, and whatnot which could be segregated 

 and used in some way. About 1.6 billion tons of it is solid wastes produced by 

 mining, along with the various acid mine waters and other liquid wastes that go 

 into the environment, and about 2 billion tons of it is agricultural wastes. It is 

 incredible that we do not use more of these wastes constructively. We must learn 

 to manage these wastes and, insofar as possible, convert them to resources. But 

 these figures also provide a measure and a warning of the way the problem is 

 increasing and cautions us about continuance of the exponential growth curves 

 that many see as undergirding all progress. For, contrary to early 1972 

 newspaper accounts stating that the latest census figures indicate an approach to 

 zero population growth, the fact is that our rate of population growth in May 

 1972 is about 0.97%, which means a 72-year doubling period for the population 

 of the United States.* Add to this a 17-year doubling period for the GNP, now 

 over one trillion dollars for the United States and three trillion for the world, 

 and think what the problem will look like at the turn of the century. 



But how about material resources? Will their availability eventually limit 

 populations if pollution or malaise does not get us first? When I speak about 

 material resources, I refer to two kinds of resources — renewable resources 

 representing food, forest products, and water and such nonrenewable resources 

 as mineral resources, especially mineral fuels and metals. I am, of course, not 

 totally ignorant of thermodynamics. I am aware that the metal resources here 

 called nonrenewable do not leave the essentially closed system that constitutes 



'The end of the 1972 census reports show U. S. fertility to have decreased to the level 

 of bare replacement growth. This is encouraging. For reasons given in this paper, we should 

 now try to reduce the level still further, at least until zero population growth is finally 

 attained in the United States, while simultaneously encouraging similar salutary trends in 

 the underdeveloped areas of the world. 



