Other nations could face financial burdens and political tensions because of a different problem: a rapid decrease in young people. Russia is already becoming an extreme case of outright population decline. Other nations that could soon experience falling populations include South Korea (around 2020) and China (by about 2030).
If Asia will host the biggest gains in the number of people over 65, Europe can claim the title of being the furthest along in "aging." It will have just two working-age people for each person over 65 by midcentury, the United Nations predicts (compared with a 4-to-1 ratio in Asia).
The US is also aging. But in an important distinction from most of the developed world, America is poised for modest population growth that may make the transition less arduous.
Still, all this global graying isn't necessarily a bad thing. While the process is fraught with challenges, core elements of the trend remain positive.
Few would consider living longer a "problem," for instance. Plus, it wasn't long ago that demographers worried about the prospect of a Malthusian "population bomb" that would strain the planet to its resource limits. Although fears of environmental catastrophe haven't evaporated, the UN now predicts that the world's population could plateau within about 50 years and then start declining.
Moreover, if people find themselves working later in life, that's not automatically disappointing.