In 1798 Thomas Malthus predicted that the population would grow faster than the food supply, leading to famine and poverty. It didn't happen then, but the neo-malthusian question remains: will the population grow to the point where the earth's resources are inadequate for its support?
Former AAPT president Al Bartlett is known to most of us as an advocate of the view that population control should be our highest priority. His book "The Essential Exponential: For the Future of our Planet" is available from the Center for Science, Mathematics, and Computer Education of the University of Nebraska - Lincoln, Lincoln, NE 68588-0131.
A limited introduction to his thoughts is in his article in Physics Today, July 2004, p. 53, and in the response letters in the November 2004 issue, p.12ff.
The growth in the earth's population is slowing, as can be seen in the graphs accompanying a description of the Malthusian Catastrophe, which contains additional links.
The question of whether there will be a "sustainability transition", i.e., whether a state will be reached that can continue into the future without incurring the Malthusian Catastrophe, involves a variety of complex factors. It has given rise to Sustainability Science . (Science 292,641, 27 April 2001.)
Our Common Journey, A transition toward sustainability, National Academy of Sciences, 1999, is the report of the Sustainability Transition Study of the National Research Council. It gives a fascinating overview of the many aspects and the present status of the sustainability problem, with quantitative detail and a wealth of references. Its 300+ pages are available free on the Internet.
Robert Kates has worked at the forefront of the question of what the sustainability transition requires, and what the obstacles are to its achievement. (He was for six years the Director of the World Hunger Program at Brown University, and before that Professor of Geography at Clark University. He was a McArthur fellow, and an awardee of the Presidential Medal of Science.) His presidential address to the Association of American Geographers in 1995 is called Labnotes from the Jeremiah Experiment: Hope for a Sustainable Transition. (This is a transcript from the author, with permission to include it here. I apologize for the fact that it is without figures and references. With some more work and time I may be able to include them. In the meantime write to me if you want them. The full publication is in the Annals of the Association of American Geographers, Vol. 85, No.4, 623, 1995.) In this address Kates examines the role of the Jeremiahs (prophets of doom) in history, starting with Malthus. The "Jeremiah Experiment" is the one we are living now, as we try to see whether our fate on the earth is, in fact, doom, or whether disaster can be averted by the achievement of a transition to sustainability.