On the Population Crisis

Foreign Policy speaks:

Not so long ago, we were warned that rising global population would inevitably bring world famine. As Paul Ehrlich wrote apocalyptically in his 1968 worldwide bestseller, The Population Bomb, "In the 1970s and 1980s hundreds of millions of people will starve to death in spite of any crash programs embarked upon now. At this late date, nothing can prevent a substantial increase in the world death rate." Obviously, Ehrlich's predicted holocaust, which assumed that the 1960s global baby boom would continue until the world faced mass famine, didn't happen. Instead, the global growth rate dropped from 2 percent in the mid-1960s to roughly half that today, with many countries no longer producing enough babies to avoid falling populations. Having too many people on the planet is no longer demographers' chief worry; now, having too few is.

I've got to say--this next paragraph is one of the oddest I've ever read:

It's true that the world's population overall will increase by roughly one-third over the next 40 years, from 6.9 to 9.1 billion, according to the U.N. Population Division. But this will be a very different kind of population growth than ever before -- driven not by birth rates, which have plummeted around the world, but primarily by an increase in the number of elderly people. Indeed, the global population of children under 5 is expected to fall by 49 million as of midcentury, while the number of people over 60 will grow by 1.2 billion. How did the world grow so gray, so quickly?

There is no way for elderly folk to increase the world's population. The young can do that. It's not as though new elderly folk just spring into being, thus magically causing the world's population to swell. So we're going to see large increases in the numbers of the young while facing a population crisis. What exactly is going on?