A HUGE conversation has developed there; here is my latest contribution (out of context, alas, but I think it still makes some points in its own rambling way):
Quite the conversation here!
I'd like to come back to two or three points I may have (unsuccessfully) made in my original comments.
One is that of the Developed Countries' footprint. It is absolutely true that we can't effectively address environmental problems by exclusively focusing on population *or* consumption; it's also true that the Developed Countries, because of (generally) better governance structures and more coherent, stronger non-governmental actors have much more latitude to do both. The relative payoff is great, considering that this, what, 25% of the world uses 40% of the resources? So again, my argument is the effectiveness of focusing resources disproportionately (but not exclusively) on the "Developed" World for a greater payoff.
Two, this would also have effects on consumption in the rest of the world, as per some earlier comments both about the Western "model" of consumptionism and the complex feedbacks between population growth and consumption. Western popular culture and industrial food are not solely to blame for worldwide increases in resource consumption intensity, but they are major contributing factors. Were the US, Canada, Europe, Australia, and Japan to seriously change their approach to population and consumption, it would strike everyone as less imperialistic and condescending to address it in the world's poorer countries. To be sure, they are contributing more than their share, but my question is -- what effective means to you propose to address population growth and consumption in Developing Countries? We do all realize here that the reason population growth projections have been decreasing is the growth of female education and political power, especially in Developing Countries, where women with free choice decide much more often to have less children? Clearly, this is an agenda that should be pushed forward with all due haste and focus, but a huge part of the reason for the population taboo are the horrible and misguided things done in its name in the past -- forced sterilization (see especially Puerto Rico's "La Operación) being a notable one. Neither forced sterilization nor handing out prophylactics have noticeable effects on population growth in absence of female political power, thus while we can speak of population growth in the Developing World, it is of utmost importance to *always* pair it with concerns for equity and access to *sufficient* consumption. Those who reproduce most are the poorest and thus many are those who consume *below* their fair share, even in Developing countries consuming net *more* than a sustainble share. (Urbanization and elite consumption no doubt account for the lion's share of this consumption as well; I'd be interested on information of resource consumption from the world's poorest rural subsistence areas - not the factory farms they may work on that consume resources but don't distribute them back to those who are disadvantaged and likely to have "too many" children).
Thus a strategy of population and consumption decrease seems best for "Developed" countries, and a focus on substantive equity, redistribution, and political power and reproductive control seems wises in the Developing countries. Not only does speaking of women's empowerment and reproductive control sound more palatable to those who've been victims of "La Operación"-like schemes in the past, it *is* the vehicle that's been shown to be successful in reduced population growth.
(And one last point -- a great article by Sloan in 2007 in Biotropica and another by Ravnborg in 2003 in World Development show some very good initial proof that local population size isn't necessarily connected to environmental degradation; this connection shows up at the national scale but is weak at the local, at least in terms of deforestation, and they both show that it is not the faster-growing population of poor that consume the most resources on agricultural frontiers, but the relatively small number of medium-and-large landowners and rich farmers, who have the money and resources to, for instance, by a small farmer's farm and expand it further into the forest. Again, equity and elite consumption confound the population issue at a local scale, and empowerment and substantive equity would do much to address it. I suppose this is my overall point -- talk of population without talk of substantive equity isn't just asking to be caricatured as old-style draconianism, but also overlooks the most effective tool we have for reducing population growth.)