Though on that, a lot of people are going to need to go without kids if we're going to maintain civilization. The majority of people who are going to cause our collapse don't exist yet, and if they never exist the resources they would otherwise take will be freed up.
I don't particularly like the idea of putting restrictions on reproduction, but if it's that or our entire civilization...
Not in the United States. Our population growth is mostly from immigration.
http://www.census.gov/population/www/projections/2009summarytables.htmlWith no net migration we would be projected to have gone from around 300,580 (thousands of people) in 2013 to around 323,020 in 2047, at which point it would start trending down. That, of course, is an unrealistic scenario, as we do have international migration. Under their 'Low Net International Migration Series' they projected the US having around 316,669 thousand people in 2013 and 328,131 in 2017 (gaining 11.462 million people in 4 years, which would cover Romney's term if he were elected), and 413,764 in 2047. The low net international migration series appears to be the closest to our current population, from what I could tell.
Anyone pay attention to Romney saying he was going to add 12 million jobs in 4 years? I wonder if his campaign calculated it so that would be just above population growth, expecting that almost nobody would check any projections. I noticed, but it doesn't seem like anyone in the media has.
It is well known that population growth is higher in less advanced countries, and slows down as a population gets a higher standard of living. You can't simply ban more than one birth in the entire world, either.
P.S. I doubt they projected the effects of climate change as far as disasters, reduced living space, reduced arable land, changed weather patterns, etc. I would expect the population in the US to eventually start to drop and the population in Canada to increase more rapidly as it will be more habitable eventually and much of the US is going to no longer have any arable land, but that population shift could be some time away. (Also, Siberia is supposed to become more habitable, which is to say, actually arable (assuming the dirt isn't unfarmable), I think, after a hundred or more years, IIRC. Depends on how fast stuff goes, it keeps going faster than projections. It's supposed to be at the end of the IPCC projections timewise, but they've turned out to be conservative underestimates of how fast it's going.)