Demography 101

There seems to be a fair amount of misinformation being purveyed in the comment thread to Loomis's post about population, though at least a few of the comments are accurate, such as the one that noted that global population is on track to level off at about 8.5 or 9 billion.  The problem is not the simple one of too many people, but rather, as a few comments noted, how environmental issues, land use, consumption patterns, and maldistribution of resources interact with population density.  The projected impact of climate change on the low-lying areas of Bangladesh (which comprise a large part of the country) is a case in point.  

The fertility trend in many countries has been downward, often sharply so, in recent decades, with sub-Saharan Africa, if I'm not mistaken, being an exception.  One would expect the poorest countries in the world not yet to have completed 'the demographic transition', i.e., birth rates in those countries have remained high while death rates have fallen (e.g., infant and child mortality in sub-Saharan Africa, although still substantial and unacceptable from a human-rights standpoint, is notably lower than 20 or 30 years ago).  I don't follow these issues all that closely but I believe what I've said here is roughly correct.  The 'demographic transition' is Demography 101, and the apparent absence of reference to it in the LGM comment thread is perhaps indicative of the thread's quality.