...the most important point about global population growth is the point David Brooks makes today—it's slowing down almost everywhere and the global trend is clearly toward birthrates that are below the replacement level. Because of "demographic momentum" and rising life expectency, relatively few countries are poised for falling population in the short-term but Russia is already there, Japan will be soon, Spain and Italy will follow, and while China is difficult to predict they're looking at the sharpest cliff.You hear a lot that if everyone lived like Americans then we would need five Earths' worth of resources to support everyone. That's true, but the converse is that if everyone lived like Ethiopians we could comfortably support 10 billion people or more. You might respond that would eat up all the available land, but if everyone in the United States lived in a city with Brooklyn's density, we could fit everyone into New Hampshire.
Again, the most critical environment issue is climate change, and it isn't caused by overpopulation. It is caused by inefficiency and poor resource allocation.