(I'll note I am using the literal definition of 'sustainable' here... able to be sustained. As an nerd, I'd really like our future ability to provide those things to be environmentally and socially sound, but that wasn't what I was talking about.)
Exponential population growth becomes a problem when we give up innovating.
the point is that if we continue to expand at the same rate MORE people will be born into terrible conditions.
It's not so easy to take the stance that technology and free market forces will solve the population problem when you see the horrible results of demand outpacing supply for basic resources in real life. In real life, demand dropping means people died. this isn't an economics class.
I think that human population can well outstrip innovation especially when you consider that an innovation now can take many years to disseminate to the world at large.
1. The increased consumption will happen without a corresponding increase in the ability to provide resources to fuel it.
2. Absolute per capita consumption of scarce resources will remain the same or greater.
3. Everyone on earth will someday have the same level of consumption.
To answer all these:
1. Without an increasing ability to provide resources, consumption levels cannot rise (there would be nothing to consume).
2. As innovation and environmental consciousness progress, absolute per capita consumption of scarce resources will hopefully decrease, in favor of consumption of non-scarce resources. (When we can transmute dirt into energy for instance, or finally have solar-powered transportation.)
3. The upper end will always rise. Someday the entire human race may on average consume at the rate Americans do today, but there will be some group/nation/whatever somewhere that consumes at a much much higher rate still.
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He is right to argue that we shouldn't just assume everyone in the world could live at Western standards right now with our current ability to procure resources, but it takes a long time to raise living standards, and our ability to procure resources steadily improves as well.
The current consumption rate in Central America probably pales in comparison to America, but would also probably seem really extravagant by US standards circa 1800.
I think the implicit motivation for all this hand-wringing about how much more the West consumes compared to the developing world has to do with some misguided assumption that it is somehow unfair. Equality sounds great in practice, but it'll never be a reality (short of a perfectly altruistic benevolent dictator). Instead of focusing on how unfair it is, why not try and do something to help those at the bottom? Innovate... pull a Dean Kamen and figure out how to cheaply purify water. If his invention works as advertised, he will turn a scarce resource (clean water) into a non-scarce one, which means it can more easily be consumed.
