How Many People Can the Earth Support?

Rating:
Summary: Probably the best book ever written on population.
Review: Definitive, yet almost breezy. Should be required reading for anyone thinking seriously about the future, be they science fiction writers, futurologists, policy analysts, strategic planners, portfolio managers or concerned citizens.

Rating:
Summary: Very good
Review: I thought that this book was a very refreshing change from the many other books I have read on the subject of overpopulation. Joel Cohen is very fair and writes without a political agenda. He helped me understand the issues and variables much better than any other author on the subject. However, I sometimes got lost in the statistics and mathematics and found some parts hard to wade through.

Rating:
Summary: What we know about constraints on population growth
Review: Obviously, the population of the world has been growing dramatically for the past few centuries. How high can it go? At how high a level can it be maintained? What restrictions are placed by the available resources, such as food and water?

This book asks many of the right questions. And it admits that we don't have all the answers. But it does give some clues about where we may be headed.

Cohen shows that basically, if we want to support people indefinitely on 3500 kilocalories per day from wheat energy, with 9000 cubic kilometers of annual fresh water supply, well, we can support only 5 billion people. We're already beyond that. Right now, we're using up resources at an incredible rate. And while the Earth could support 10 billion people in theory, it is hard to see how it could do that for long in practice.

The author thinks that we'll never get to the absolute maximum that the Earth can support. Most people would all be right on the edge of starvation, and we'd simply be unable and unwilling to stay in that state indefinitely. But I did realize after reading this book that we could stay at about 5 billion people for a very long time if we put our minds to it. Standards of living would not be high, but they would be tolerable for the majority, and the ones who found such a life acceptable would keep having children who found it acceptable.

Those of us who have political views ought to wonder if time is on our side or not. And that is why I think it makes sense to try to imagine what options are available for our mutual future. That's why I think this book is worth reading.

Rating:
Summary: Finally, an honest book
Review: This is a book that should be used to bludgeon every Julian Simon fan and every Zero Population Growth fanatic to depth. (You hear that Brian Cornell at overpopulation.com? I'm coming over your place with a hardcover edition to smash your cornucopian little mind!) This book doesn't pander to either the alarmists who think doom is just a year or two ahead, or to the giddy technocrats a la Julian Simon who think that technology combined with human beings' ineffable goodness is about to bring about a golden age like the United Federation of Planets on Star Trek. For straight thinking on population growth, read this book.

Rating:
Summary: Typically naive
Review: Using the Rule Of 70, a population which grows at 1% per annum doubles in 70 years. A population which grows at 2 % doubles in 35 years. Both are considered fine examples of exponential growth (each at a constant rate of growth, producing a lovely exponential curve). The question is, if a population grows at variable rates, but always between 1 and 2 % (and thus
is guarenteed to double in 35 to 70 years) - is this exponential growth?

Not only does Cohen fail to discuss the variable compound interest version of the Malthusian Growth Model, but he fails to adequately explain the importance of negative rates of growth.