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Isn't it perfectly sustainable if adults have, on average, two children per generation? (Since each child has two parents, you can account for them twice.) Tha

Isn't it perfectly sustainable if adults have, on average, two children per generation? (Since each child has two parents, you can account for them twice.) That case (<2) is the case for most of the developed world.

jchw 9y ago
No - because the U.S. life expectancy is somewhere in the ball park of 80 years, whereas adulthood is reached in a forth of that. So before the average parent dies off, they will have seen around 2 or 3 generations of adults who are all having children, and their children having children. Also, in the U.S.'s case, you have to consider externalities like immigration, and the fact that some areas are already massively overpopulated. Though I was definitely wrong to say 'exponential growth' since that isn't actually true.
- sremani 9y ago
  USA is one of the most under-populated country in the world. Even its densest populated areas in the North East is still "expansive". From arable land to person ratio, US has lot of room to grow. The over-population problem is not of US, or even not of even Americas (North and South) they are pretty much stabilized at around 1.1 Billion. The coming population "boom" is in Africa which will likely grow from 1 Billion to 4 Billion.
  - jchw 9y ago
    I don't think at all that the U.S. is overpopulated, but I think that there are areas of the U.S. that are severely overpopulated. The distribution of the population isn't equal, most people would not be able to thrive at all in rural areas.
  - jdietrich 9y ago
    Americans use such a grossly disproportionate share of the world's resources that the US is drastically overpopulated compared to African nations. We could fit the entire world's population into a city the size of Texas at a perfectly liveable density, but we can't magic up more oil or copper or neodymium. We have enough arable land to easily feed 20 billion people, but not if we squander 95% of those calories by raising cattle. Population growth is a total non-issue if we're halfway sensible about how we use finite resources. http://journals.sagepub.com/doi/10.1177/0956247806063978 http://journals.sagepub.com/doi/10.1177/0956247806063978 http://data.footprintnetwork.org/ http://data.footprintnetwork.org/

jchw 9y ago

No - because the U.S. life expectancy is somewhere in the ball park of 80 years, whereas adulthood is reached in a forth of that. So before the average parent dies off, they will have seen around 2 or 3 generations of adults who are all having children, and their children having children. Also, in the U.S.'s case, you have to consider externalities like immigration, and the fact that some areas are already massively overpopulated. Though I was definitely wrong to say 'exponential growth' since that isn't actually true.

sremani 9y ago
USA is one of the most under-populated country in the world. Even its densest populated areas in the North East is still "expansive". From arable land to person ratio, US has lot of room to grow. The over-population problem is not of US, or even not of even Americas (North and South) they are pretty much stabilized at around 1.1 Billion. The coming population "boom" is in Africa which will likely grow from 1 Billion to 4 Billion.
- jchw 9y ago
  I don't think at all that the U.S. is overpopulated, but I think that there are areas of the U.S. that are severely overpopulated. The distribution of the population isn't equal, most people would not be able to thrive at all in rural areas.
- jdietrich 9y ago
  Americans use such a grossly disproportionate share of the world's resources that the US is drastically overpopulated compared to African nations. We could fit the entire world's population into a city the size of Texas at a perfectly liveable density, but we can't magic up more oil or copper or neodymium. We have enough arable land to easily feed 20 billion people, but not if we squander 95% of those calories by raising cattle. Population growth is a total non-issue if we're halfway sensible about how we use finite resources. http://journals.sagepub.com/doi/10.1177/0956247806063978 http://journals.sagepub.com/doi/10.1177/0956247806063978 http://data.footprintnetwork.org/ http://data.footprintnetwork.org/