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How Many People Can the Earth Support? Paperback – September 17, 1996
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From Publishers Weekly
Copyright 1996 Reed Business Information, Inc.
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Top Customer Reviews
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.
Having said this by way of praise, I would also like to note a couple weaknesses. The most obvious one is something that Cohen simply can't help. Eighteen years after publication some of the data is out of date. Therefore, the careful reader ought to find more recent sources for the data that Cohen cites.
Cohen also seems to underestimate the ability of human beings to find new resources and new ways of economically abstracting existing resources. As some have pointed out, there are no resources per se. Something becomes a resource only when someone finds a use for it. (Case in point: For most of human history petroleum was not a resource.) Moreover, many resources are available in far greater abundance than the official calculations would lead one to believe. Such calculations are generally based on known supplies that can be economically extracted. As we know from the huge reserves of oil that are currently being extracted from shale through hydraulic fracturing (fracking), past estimates of oil reserves seriously underestimated the amount of oil that is now available to us.Read more ›
We see what has happened to India and China in the years since publication. They are getting richer; automobile use is exploding. Therefore, the lower end of his estimates, five billion, appears more likely.
A trend which Cohen certainly didn't predict is that vast decrease in fertility. It is below the replacement rate (2.1 children per woman) in countries accounting for the majority of the world population. It is vastly below replacement in every country dominated by whites and north Asians, the peoples who are driving the world economy. There has been an abrupt cultural shift in those places. Having children is not valued or supported by the society. Individuals are not encouraged (much) to marry and have children. Conversely, lifestyles / sexuality decisions inconsistent with having kids are gaining recognition everywhere.
Cohen's groundwork is an essential support for analyzing more recent trends.
Most Recent Customer Reviews
Here is what I say in my own book (The Laws of Physics Are On My Side, 2013:57).
"For further definitions of carrying capacity, one can turn to Joel Cohen’s How Many... Read more
A very well researched work. It should be read by the leadership on the right and left. To say we are doomed is an understatement.Published on June 6, 2011 by Ken Counts
A lot of history of calculations for possible saturation point but not always the sustainable number. Has no actual conclusion or even a guess. Read morePublished on December 4, 2010 by jd soure
This is a highly technical and theoretical treatment with a heavy emphasis on quantitative analysis rather than social science or policy. Read morePublished on September 11, 2009 by James Bruner
""Surprisingly, in spite of the abundant data to the contrary, many people believe that human population grows exponentially. Read more