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>In particular, we argue that the whole world can reach and maintain American standards of living with a population of even 15 billion. That's one doubling awa

>In particular, we argue that the whole world can reach and maintain American standards of living with a population of even 15 billion. That's one doubling away from the current population. There's no particular reason to believe population will never exceed 15 billion.

jerf 15y ago
Actually, the claim that it will is the one not currently supported by evidence. The UN currently estimates the peak of world population will be 9.22 billion in 2075, followed by a general decline, assuming current trends [1]. Now, I'd like to think we continue to extend lifespan, but birth rates are dropping. Against all (first-order) biology, when humans become wealthier, they have fewer children, and this result is very robust now, not just the aberration of one particular culture. [1]: http://www.un.org/esa/population/publications/longrange2/WorldPop2300final.pdf http://www.un.org/esa/population/publications/longrange2/Wor... , second paragraph of the executive summary. Oh, and I'm just quoting the 9.22; I think that's an absurd number of significant digits but one should quote sources as directly as possible.
- rsheridan6 15y ago
  to last billions of years. You yourself think that projecting the tens of millions place 64 years in the future is an absurd number of significant digits. How many significant digits do you think is appropriate in a time frame 100M years longer? Even the UN itself only purports to project population trends until 2300, which is far short of a billion years, as hubristic as it is. Also, the UN projections have some unjustified assumptions. From page 7, under section C: >Over the long run, total fertility is projected to settle at 1.85 children per woman in each country—in between the current rate for Northern America (which is just below replacement level) and the rate for Europe (which is currently well below). This figure is somewhat arbitrary In the longer run they expect the growth rate of all countries to stabilize at 0: >The eventually similar growth between more developed and less developed regions is produced by similar long-range assumptions, especially the assumptions that fertility will fall in all countries below replacement (in the medium scenario) and rebound to replacement after a period largely similar across countries of a century or so. Starting their fertility declines later, less developed regions will reach low fertility levels after more developed regions but also stay at these levels until a later date. Of course population stabilizes at a rate not too much higher than the present rate if you assume fertility rates converge around the replacement level. Garbage in, garbage out.

jerf 15y ago

Actually, the claim that it will is the one not currently supported by evidence. The UN currently estimates the peak of world population will be 9.22 billion in 2075, followed by a general decline, assuming current trends [1]. Now, I'd like to think we continue to extend lifespan, but birth rates are dropping. Against all (first-order) biology, when humans become wealthier, they have fewer children, and this result is very robust now, not just the aberration of one particular culture. [1]: http://www.un.org/esa/population/publications/longrange2/WorldPop2300final.pdf http://www.un.org/esa/population/publications/longrange2/Wor... , second paragraph of the executive summary. Oh, and I'm just quoting the 9.22; I think that's an absurd number of significant digits but one should quote sources as directly as possible.

rsheridan6 15y ago
to last billions of years. You yourself think that projecting the tens of millions place 64 years in the future is an absurd number of significant digits. How many significant digits do you think is appropriate in a time frame 100M years longer? Even the UN itself only purports to project population trends until 2300, which is far short of a billion years, as hubristic as it is. Also, the UN projections have some unjustified assumptions. From page 7, under section C: >Over the long run, total fertility is projected to settle at 1.85 children per woman in each country—in between the current rate for Northern America (which is just below replacement level) and the rate for Europe (which is currently well below). This figure is somewhat arbitrary In the longer run they expect the growth rate of all countries to stabilize at 0: >The eventually similar growth between more developed and less developed regions is produced by similar long-range assumptions, especially the assumptions that fertility will fall in all countries below replacement (in the medium scenario) and rebound to replacement after a period largely similar across countries of a century or so. Starting their fertility declines later, less developed regions will reach low fertility levels after more developed regions but also stay at these levels until a later date. Of course population stabilizes at a rate not too much higher than the present rate if you assume fertility rates converge around the replacement level. Garbage in, garbage out.